Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Matthias Kaehlcke]

El Fri, Jul 14, 2017 at 03:43:35PM -0700 Grant Grundler ha dit:

> On Fri, Jul 14, 2017 at 2:35 PM, Daniel Vetter  wrote:
> > On Fri, Jul 14, 2017 at 7:32 PM, Grant Grundler  
> > wrote:
> >> On Fri, Jul 14, 2017 at 2:11 AM, Jani Nikula
> >>  wrote:
> >>> On Thu, 13 Jul 2017, Stéphane Marchesin  
> >>> wrote:
>  So, if you think this is wrong, can you fix this warning in a way that
>  you'd like?
> >>>
> >>> As I replied previously [1], with more background, fixing the warnings
> >>> properly, in a way that actually improves the code instead of making it
> >>> worse, would mean a bunch of churn that's not just purely mechanical
> >>> conversion.
> >>
> >> That's fair.
> >>
> >>> Unless you can point out a bug which is actually caused by mixing the
> >>> types (which is mostly intentional, see the background) I have a hard
> >>> time telling people this should be a priority.
> >>
> >> This feels like "can't see the forest because of the trees".
> >>
> >> The original patch was submitted in order to compile cleanly using
> >> clang and the above suggests using clang is not important.  Using
> >> clang is important to Matthias and the Chrome OS organization for many
> >> good reasons - including better warnings.
> >>
> >> The original patch message was clear that clang was generating the
> >> warning. This isn't the only patch mka has sent to kernel devs. What
> >> one can infer is Chrome OS is trying to move to clang (like other
> >> Google products _already_ have.)  My impression is all these products
> >> are a priority to Intel - but it would be good to know otherwise.
> >>
> >>> Definitely something we'd
> >>> like to do in the long run and pedantically correct (and I tend to
> >>> prefer code that way) but we certainly have more important things to do.
> >>
> >> The long run is now. Everyone agrees the code should change and you
> >> don't have to do it. Matthias submitted an unacceptable patch and
> >> giving him some concrete guidance on what would be acceptable would
> >> enable him to implement/test it (or anyone else could for that
> >> matter).  Can you do that?
> >>
> >> Just give an example of what the "right" API looks like and see where it 
> >> goes.
> >
> > We've replied and discussed on May 5th what that roughly should be,
> > right when Matthias pinged us. The original submission unfortunately
> > fell through the cracks (it happens, not much we can do with this
> > flood). Matthias didn't seem to have any questions about the proposed
> > solutions (we laid out both the minimal short-term fix to unconfuse
> > things, and what might be done on top), I think a reasonable
> > assumption was that it's all clear. Otherwise he should have asked.
> 
> Indeed!
> 
> After briefly chatting with Stephane and mka, it seems the difference
> between short-term fix and "done on top" were not clear.
> 
> > Now, over 2 months later (and complete silence from your side) there's
> > suddenly mass panic and multiple escalations on all available
> > channels, which feels like a rather decent overreaction and not a
> > terrible constructive way to collaborate on the upstream codebase.
> 
> I'm sorry - I'm not on the other channels and I didn't see any mass
> panic. I agree that's not a collaborative. The previous answer in this
> thread didn't seem particularly collaborative either though.
> 
> The silence was partly due to mka working on other "clang enablement" patches:

Yes, sorry for the silence :(

With my lack of expertise with this driver and graphics in general I
wasn't sure if I'd take up the "done on top" solution and shifted my
attention to other clang related issues.

> $ pwclient list -w m...@chromium.org
> Patches submitted by Matthias Kaehlcke :
> ID  StateName
> --  -
> 9668095 Superseded   mac80211: Fix clang warning about constant
> operand in logical operation
> 9668479 Accepted ath9k: Add cast to u8 to FREQ2FBIN macro
> 9668643 Accepted [v2] mac80211: Fix clang warning about constant
> operand in logical operation
> 9679753 Accepted [v2] cfg80211: Fix array-bounds warning in fragment copy
> 9684547 Accepted mac80211: ibss: Fix channel type enum in
> ieee80211_sta_join_ibss()
> 9684629 Accepted nl80211: Fix enum type of variable in
> nl80211_put_sta_rate()
> 
> > Anyway, I've done the quick draft for the function declaration changes
> > that would clear up the confusion, just needs a clang run to update
> > all the parameters to match, and passed that on to Stéphane Marchesin.

Thanks, that is helpful!

> Awesome - thanks! :)
> 
> > I expect you to follow up with the corresponding patch right away.
> 
> mka said "he would take a look at it". But knowing how he understates
> things in a typical "German Engineer" way, I'm optimistic it will be
> more than that. Thanks!
> 
> cheers,
> grant
> 
> >
> > Thanks a lot.
> >

Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Grant Grundler]

On Fri, Jul 14, 2017 at 2:35 PM, Daniel Vetter  wrote:
> On Fri, Jul 14, 2017 at 7:32 PM, Grant Grundler  wrote:
>> On Fri, Jul 14, 2017 at 2:11 AM, Jani Nikula
>>  wrote:
>>> On Thu, 13 Jul 2017, Stéphane Marchesin  
>>> wrote:
 So, if you think this is wrong, can you fix this warning in a way that
 you'd like?
>>>
>>> As I replied previously [1], with more background, fixing the warnings
>>> properly, in a way that actually improves the code instead of making it
>>> worse, would mean a bunch of churn that's not just purely mechanical
>>> conversion.
>>
>> That's fair.
>>
>>> Unless you can point out a bug which is actually caused by mixing the
>>> types (which is mostly intentional, see the background) I have a hard
>>> time telling people this should be a priority.
>>
>> This feels like "can't see the forest because of the trees".
>>
>> The original patch was submitted in order to compile cleanly using
>> clang and the above suggests using clang is not important.  Using
>> clang is important to Matthias and the Chrome OS organization for many
>> good reasons - including better warnings.
>>
>> The original patch message was clear that clang was generating the
>> warning. This isn't the only patch mka has sent to kernel devs. What
>> one can infer is Chrome OS is trying to move to clang (like other
>> Google products _already_ have.)  My impression is all these products
>> are a priority to Intel - but it would be good to know otherwise.
>>
>>> Definitely something we'd
>>> like to do in the long run and pedantically correct (and I tend to
>>> prefer code that way) but we certainly have more important things to do.
>>
>> The long run is now. Everyone agrees the code should change and you
>> don't have to do it. Matthias submitted an unacceptable patch and
>> giving him some concrete guidance on what would be acceptable would
>> enable him to implement/test it (or anyone else could for that
>> matter).  Can you do that?
>>
>> Just give an example of what the "right" API looks like and see where it 
>> goes.
>
> We've replied and discussed on May 5th what that roughly should be,
> right when Matthias pinged us. The original submission unfortunately
> fell through the cracks (it happens, not much we can do with this
> flood). Matthias didn't seem to have any questions about the proposed
> solutions (we laid out both the minimal short-term fix to unconfuse
> things, and what might be done on top), I think a reasonable
> assumption was that it's all clear. Otherwise he should have asked.

Indeed!

After briefly chatting with Stephane and mka, it seems the difference
between short-term fix and "done on top" were not clear.

> Now, over 2 months later (and complete silence from your side) there's
> suddenly mass panic and multiple escalations on all available
> channels, which feels like a rather decent overreaction and not a
> terrible constructive way to collaborate on the upstream codebase.

I'm sorry - I'm not on the other channels and I didn't see any mass
panic. I agree that's not a collaborative. The previous answer in this
thread didn't seem particularly collaborative either though.

The silence was partly due to mka working on other "clang enablement" patches:

$ pwclient list -w m...@chromium.org
Patches submitted by Matthias Kaehlcke :
ID  StateName
--  -
9668095 Superseded   mac80211: Fix clang warning about constant
operand in logical operation
9668479 Accepted ath9k: Add cast to u8 to FREQ2FBIN macro
9668643 Accepted [v2] mac80211: Fix clang warning about constant
operand in logical operation
9679753 Accepted [v2] cfg80211: Fix array-bounds warning in fragment copy
9684547 Accepted mac80211: ibss: Fix channel type enum in
ieee80211_sta_join_ibss()
9684629 Accepted nl80211: Fix enum type of variable in
nl80211_put_sta_rate()

> Anyway, I've done the quick draft for the function declaration changes
> that would clear up the confusion, just needs a clang run to update
> all the parameters to match, and passed that on to Stéphane Marchesin.

Awesome - thanks! :)

> I expect you to follow up with the corresponding patch right away.

mka said "he would take a look at it". But knowing how he understates
things in a typical "German Engineer" way, I'm optimistic it will be
more than that. Thanks!

cheers,
grant

>
> Thanks a lot.
>
> Yours, Daniel
>
> For reference the diff, but probably whitespace mangled because the
> real machine is down already:
>
> diff --git a/drivers/gpu/drm/i915/intel_fifo_underrun.c
> b/drivers/gpu/drm/i915/intel_fifo_underrun.c
> index d484862cc7df..21c221b4ae57 100644
> --- a/drivers/gpu/drm/i915/intel_fifo_underrun.c
> +++ b/drivers/gpu/drm/i915/intel_fifo_underrun.c
> @@ -313,7 +313,7 @@ bool intel_set_cpu_fifo_underrun_reporting(struct
> drm_i915_private *dev_priv,
>   * Returns the previous state of 

Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Daniel Vetter]

On Fri, Jul 14, 2017 at 7:32 PM, Grant Grundler  wrote:
> On Fri, Jul 14, 2017 at 2:11 AM, Jani Nikula
>  wrote:
>> On Thu, 13 Jul 2017, Stéphane Marchesin  wrote:
>>> So, if you think this is wrong, can you fix this warning in a way that
>>> you'd like?
>>
>> As I replied previously [1], with more background, fixing the warnings
>> properly, in a way that actually improves the code instead of making it
>> worse, would mean a bunch of churn that's not just purely mechanical
>> conversion.
>
> That's fair.
>
>> Unless you can point out a bug which is actually caused by mixing the
>> types (which is mostly intentional, see the background) I have a hard
>> time telling people this should be a priority.
>
> This feels like "can't see the forest because of the trees".
>
> The original patch was submitted in order to compile cleanly using
> clang and the above suggests using clang is not important.  Using
> clang is important to Matthias and the Chrome OS organization for many
> good reasons - including better warnings.
>
> The original patch message was clear that clang was generating the
> warning. This isn't the only patch mka has sent to kernel devs. What
> one can infer is Chrome OS is trying to move to clang (like other
> Google products _already_ have.)  My impression is all these products
> are a priority to Intel - but it would be good to know otherwise.
>
>> Definitely something we'd
>> like to do in the long run and pedantically correct (and I tend to
>> prefer code that way) but we certainly have more important things to do.
>
> The long run is now. Everyone agrees the code should change and you
> don't have to do it. Matthias submitted an unacceptable patch and
> giving him some concrete guidance on what would be acceptable would
> enable him to implement/test it (or anyone else could for that
> matter).  Can you do that?
>
> Just give an example of what the "right" API looks like and see where it goes.

We've replied and discussed on May 5th what that roughly should be,
right when Matthias pinged us. The original submission unfortunately
fell through the cracks (it happens, not much we can do with this
flood). Matthias didn't seem to have any questions about the proposed
solutions (we laid out both the minimal short-term fix to unconfuse
things, and what might be done on top), I think a reasonable
assumption was that it's all clear. Otherwise he should have asked.

Now, over 2 months later (and complete silence from your side) there's
suddenly mass panic and multiple escalations on all available
channels, which feels like a rather decent overreaction and not a
terrible constructive way to collaborate on the upstream codebase.

Anyway, I've done the quick draft for the function declaration changes
that would clear up the confusion, just needs a clang run to update
all the parameters to match, and passed that on to Stéphane Marchesin.

I expect you to follow up with the corresponding patch right away.

Thanks a lot.

Yours, Daniel

For reference the diff, but probably whitespace mangled because the
real machine is down already:

diff --git a/drivers/gpu/drm/i915/intel_fifo_underrun.c
b/drivers/gpu/drm/i915/intel_fifo_underrun.c
index d484862cc7df..21c221b4ae57 100644
--- a/drivers/gpu/drm/i915/intel_fifo_underrun.c
+++ b/drivers/gpu/drm/i915/intel_fifo_underrun.c
@@ -313,7 +313,7 @@ bool intel_set_cpu_fifo_underrun_reporting(struct
drm_i915_private *dev_priv,
  * Returns the previous state of underrun reporting.
  */
 bool intel_set_pch_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
-   enum transcoder pch_transcoder,
+   enum pipe pch_transcoder,
bool enable)
 {
  struct intel_crtc *crtc =
@@ -390,7 +390,7 @@ void intel_cpu_fifo_underrun_irq_handler(struct
drm_i915_private *dev_priv,
  * interrupt to avoid an irq storm.
  */
 void intel_pch_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
- enum transcoder pch_transcoder)
+ enum pipe pch_transcoder)
 {
  if (intel_set_pch_fifo_underrun_reporting(dev_priv, pch_transcoder,
   false)) {


-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Grant Grundler]

On Fri, Jul 14, 2017 at 2:11 AM, Jani Nikula
 wrote:
> On Thu, 13 Jul 2017, Stéphane Marchesin  wrote:
>> So, if you think this is wrong, can you fix this warning in a way that
>> you'd like?
>
> As I replied previously [1], with more background, fixing the warnings
> properly, in a way that actually improves the code instead of making it
> worse, would mean a bunch of churn that's not just purely mechanical
> conversion.

That's fair.

> Unless you can point out a bug which is actually caused by mixing the
> types (which is mostly intentional, see the background) I have a hard
> time telling people this should be a priority.

This feels like "can't see the forest because of the trees".

The original patch was submitted in order to compile cleanly using
clang and the above suggests using clang is not important.  Using
clang is important to Matthias and the Chrome OS organization for many
good reasons - including better warnings.

The original patch message was clear that clang was generating the
warning. This isn't the only patch mka has sent to kernel devs. What
one can infer is Chrome OS is trying to move to clang (like other
Google products _already_ have.)  My impression is all these products
are a priority to Intel - but it would be good to know otherwise.

> Definitely something we'd
> like to do in the long run and pedantically correct (and I tend to
> prefer code that way) but we certainly have more important things to do.

The long run is now. Everyone agrees the code should change and you
don't have to do it. Matthias submitted an unacceptable patch and
giving him some concrete guidance on what would be acceptable would
enable him to implement/test it (or anyone else could for that
matter).  Can you do that?

Just give an example of what the "right" API looks like and see where it goes.

cheers,
grant

>
> BR,
> Jani.
>
> [1] http://mid.mail-archive.com/87wp9rahjy.fsf@intel.com
>
>
> --
> Jani Nikula, Intel Open Source Technology Center
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Jani Nikula]

On Thu, 13 Jul 2017, Stéphane Marchesin  wrote:
> So, if you think this is wrong, can you fix this warning in a way that
> you'd like?

As I replied previously [1], with more background, fixing the warnings
properly, in a way that actually improves the code instead of making it
worse, would mean a bunch of churn that's not just purely mechanical
conversion.

Unless you can point out a bug which is actually caused by mixing the
types (which is mostly intentional, see the background) I have a hard
time telling people this should be a priority. Definitely something we'd
like to do in the long run and pedantically correct (and I tend to
prefer code that way) but we certainly have more important things to do.

BR,
Jani.

[1] http://mid.mail-archive.com/87wp9rahjy.fsf@intel.com


-- 
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Stéphane Marchesin]

On Thu, Jul 13, 2017 at 10:42 AM, Ville Syrjälä
 wrote:
> On Thu, Jul 13, 2017 at 09:23:11AM -0700, Stéphane Marchesin wrote:
>> On Thu, Jul 13, 2017 at 3:13 AM, Ville Syrjälä
>>  wrote:
>> > On Wed, Jul 12, 2017 at 07:28:14PM -0700, Stéphane Marchesin wrote:
>> >> On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
>> >>  wrote:
>> >> >
>> >> > On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
>> >> > > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
>> >> > >
>> >> > > > In several instances the driver passes an 'enum pipe' value to a
>> >> > > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x 
>> >> > > > and
>> >> > > > TRANSCODER_x have the same values this doesn't cause functional
>> >> > > > problems. Still it is incorrect and causes clang to generate 
>> >> > > > warnings
>> >> > > > like this:
>> >> > > >
>> >> > > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
>> >> > > >   conversion from enumeration type 'enum transcoder' to different
>> >> > > >   enumeration type 'enum pipe' [-Wenum-conversion]
>> >> > > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
>> >> > > >
>> >> > > > Change the code to pass values of the type expected by the callee.
>> >> > > >
>> >> > > > Signed-off-by: Matthias Kaehlcke 
>> >> > > > ---
>> >> > > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
>> >> > > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
>> >> > > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
>> >> > > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
>> >> > > >  4 files changed, 14 insertions(+), 8 deletions(-)
>> >> > >
>> >> > > Ping, any comments on this patch?
>> >> >
>> >> > I'm not convinced the patch is making things any better really. To
>> >> > fix this really properly, I think we'd need to introduce a new enum
>> >> > pch_transcoder and thus avoid the confusion of which type of
>> >> > transcoder we're talking about. Currently most places expect an
>> >> > enum pipe when dealing with PCH transcoders, and enum transcoder
>> >> > when dealing with CPU transcoders. But there are some exceptions
>> >> > of course.
>> >>
>> >>
>> >> I don't follow -- these functions take an enum transcoder; what's
>> >> wrong about passing what they expect? It seems like what you are
>> >> asking for has nothing to do with the warning here...
>> >
>> > There's a warning? I don't get any.
>>
>> Yup, clang generates a warning.
>>
>> >
>> > Anyways, I just don't see much point in blindly changing the types
>> > because it doesn't actually solve the underlying confusion for human
>> > readers. It might even make it worse, not sure.
>>
>> The function expects type A, you pass type B, how can that ever be the
>> right thing to do?
>
> Because maybe the function should be taking in type B instead.

So, if you think this is wrong, can you fix this warning in a way that
you'd like?

Stéphane

>
> --
> Ville Syrjälä
> Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Ville Syrjälä]

On Thu, Jul 13, 2017 at 09:23:11AM -0700, Stéphane Marchesin wrote:
> On Thu, Jul 13, 2017 at 3:13 AM, Ville Syrjälä
>  wrote:
> > On Wed, Jul 12, 2017 at 07:28:14PM -0700, Stéphane Marchesin wrote:
> >> On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
> >>  wrote:
> >> >
> >> > On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> >> > > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> >> > >
> >> > > > In several instances the driver passes an 'enum pipe' value to a
> >> > > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x 
> >> > > > and
> >> > > > TRANSCODER_x have the same values this doesn't cause functional
> >> > > > problems. Still it is incorrect and causes clang to generate warnings
> >> > > > like this:
> >> > > >
> >> > > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> >> > > >   conversion from enumeration type 'enum transcoder' to different
> >> > > >   enumeration type 'enum pipe' [-Wenum-conversion]
> >> > > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> >> > > >
> >> > > > Change the code to pass values of the type expected by the callee.
> >> > > >
> >> > > > Signed-off-by: Matthias Kaehlcke 
> >> > > > ---
> >> > > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> >> > > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> >> > > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> >> > > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> >> > > >  4 files changed, 14 insertions(+), 8 deletions(-)
> >> > >
> >> > > Ping, any comments on this patch?
> >> >
> >> > I'm not convinced the patch is making things any better really. To
> >> > fix this really properly, I think we'd need to introduce a new enum
> >> > pch_transcoder and thus avoid the confusion of which type of
> >> > transcoder we're talking about. Currently most places expect an
> >> > enum pipe when dealing with PCH transcoders, and enum transcoder
> >> > when dealing with CPU transcoders. But there are some exceptions
> >> > of course.
> >>
> >>
> >> I don't follow -- these functions take an enum transcoder; what's
> >> wrong about passing what they expect? It seems like what you are
> >> asking for has nothing to do with the warning here...
> >
> > There's a warning? I don't get any.
> 
> Yup, clang generates a warning.
> 
> >
> > Anyways, I just don't see much point in blindly changing the types
> > because it doesn't actually solve the underlying confusion for human
> > readers. It might even make it worse, not sure.
> 
> The function expects type A, you pass type B, how can that ever be the
> right thing to do?

Because maybe the function should be taking in type B instead.

-- 
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Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Stéphane Marchesin]

On Thu, Jul 13, 2017 at 3:13 AM, Ville Syrjälä
 wrote:
> On Wed, Jul 12, 2017 at 07:28:14PM -0700, Stéphane Marchesin wrote:
>> On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
>>  wrote:
>> >
>> > On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
>> > > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
>> > >
>> > > > In several instances the driver passes an 'enum pipe' value to a
>> > > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
>> > > > TRANSCODER_x have the same values this doesn't cause functional
>> > > > problems. Still it is incorrect and causes clang to generate warnings
>> > > > like this:
>> > > >
>> > > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
>> > > >   conversion from enumeration type 'enum transcoder' to different
>> > > >   enumeration type 'enum pipe' [-Wenum-conversion]
>> > > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
>> > > >
>> > > > Change the code to pass values of the type expected by the callee.
>> > > >
>> > > > Signed-off-by: Matthias Kaehlcke 
>> > > > ---
>> > > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
>> > > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
>> > > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
>> > > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
>> > > >  4 files changed, 14 insertions(+), 8 deletions(-)
>> > >
>> > > Ping, any comments on this patch?
>> >
>> > I'm not convinced the patch is making things any better really. To
>> > fix this really properly, I think we'd need to introduce a new enum
>> > pch_transcoder and thus avoid the confusion of which type of
>> > transcoder we're talking about. Currently most places expect an
>> > enum pipe when dealing with PCH transcoders, and enum transcoder
>> > when dealing with CPU transcoders. But there are some exceptions
>> > of course.
>>
>>
>> I don't follow -- these functions take an enum transcoder; what's
>> wrong about passing what they expect? It seems like what you are
>> asking for has nothing to do with the warning here...
>
> There's a warning? I don't get any.

Yup, clang generates a warning.

>
> Anyways, I just don't see much point in blindly changing the types
> because it doesn't actually solve the underlying confusion for human
> readers. It might even make it worse, not sure.

The function expects type A, you pass type B, how can that ever be the
right thing to do?

Stéphane


>
> --
> Ville Syrjälä
> Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Daniel Vetter]

On Thu, Jul 13, 2017 at 01:13:51PM +0300, Ville Syrjälä wrote:
> On Wed, Jul 12, 2017 at 07:28:14PM -0700, Stéphane Marchesin wrote:
> > On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
> >  wrote:
> > >
> > > On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> > > > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> > > >
> > > > > In several instances the driver passes an 'enum pipe' value to a
> > > > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x 
> > > > > and
> > > > > TRANSCODER_x have the same values this doesn't cause functional
> > > > > problems. Still it is incorrect and causes clang to generate warnings
> > > > > like this:
> > > > >
> > > > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> > > > >   conversion from enumeration type 'enum transcoder' to different
> > > > >   enumeration type 'enum pipe' [-Wenum-conversion]
> > > > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> > > > >
> > > > > Change the code to pass values of the type expected by the callee.
> > > > >
> > > > > Signed-off-by: Matthias Kaehlcke 
> > > > > ---
> > > > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> > > > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> > > > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> > > > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> > > > >  4 files changed, 14 insertions(+), 8 deletions(-)
> > > >
> > > > Ping, any comments on this patch?
> > >
> > > I'm not convinced the patch is making things any better really. To
> > > fix this really properly, I think we'd need to introduce a new enum
> > > pch_transcoder and thus avoid the confusion of which type of
> > > transcoder we're talking about. Currently most places expect an
> > > enum pipe when dealing with PCH transcoders, and enum transcoder
> > > when dealing with CPU transcoders. But there are some exceptions
> > > of course.
> > 
> > 
> > I don't follow -- these functions take an enum transcoder; what's
> > wrong about passing what they expect? It seems like what you are
> > asking for has nothing to do with the warning here...
> 
> There's a warning? I don't get any.
> 
> Anyways, I just don't see much point in blindly changing the types
> because it doesn't actually solve the underlying confusion for human
> readers. It might even make it worse, not sure.

Yeah the current patch just makes it worse. Either enum pch_transcoder, or
the enum pipe changes I suggested somewhere else. Blindly fixing type
mismatches without actually fixing the underlying confusion isn't really
useful work. And at least the switch to enum pipe for pch won't be (much)
bigger.
-Daniel
-- 
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Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Ville Syrjälä]

On Wed, Jul 12, 2017 at 07:28:14PM -0700, Stéphane Marchesin wrote:
> On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
>  wrote:
> >
> > On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> > > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> > >
> > > > In several instances the driver passes an 'enum pipe' value to a
> > > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
> > > > TRANSCODER_x have the same values this doesn't cause functional
> > > > problems. Still it is incorrect and causes clang to generate warnings
> > > > like this:
> > > >
> > > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> > > >   conversion from enumeration type 'enum transcoder' to different
> > > >   enumeration type 'enum pipe' [-Wenum-conversion]
> > > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> > > >
> > > > Change the code to pass values of the type expected by the callee.
> > > >
> > > > Signed-off-by: Matthias Kaehlcke 
> > > > ---
> > > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> > > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> > > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> > > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> > > >  4 files changed, 14 insertions(+), 8 deletions(-)
> > >
> > > Ping, any comments on this patch?
> >
> > I'm not convinced the patch is making things any better really. To
> > fix this really properly, I think we'd need to introduce a new enum
> > pch_transcoder and thus avoid the confusion of which type of
> > transcoder we're talking about. Currently most places expect an
> > enum pipe when dealing with PCH transcoders, and enum transcoder
> > when dealing with CPU transcoders. But there are some exceptions
> > of course.
> 
> 
> I don't follow -- these functions take an enum transcoder; what's
> wrong about passing what they expect? It seems like what you are
> asking for has nothing to do with the warning here...

There's a warning? I don't get any.

Anyways, I just don't see much point in blindly changing the types
because it doesn't actually solve the underlying confusion for human
readers. It might even make it worse, not sure.

-- 
Ville Syrjälä
Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Stéphane Marchesin]

On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
 wrote:
>
> On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> >
> > > In several instances the driver passes an 'enum pipe' value to a
> > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
> > > TRANSCODER_x have the same values this doesn't cause functional
> > > problems. Still it is incorrect and causes clang to generate warnings
> > > like this:
> > >
> > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> > >   conversion from enumeration type 'enum transcoder' to different
> > >   enumeration type 'enum pipe' [-Wenum-conversion]
> > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> > >
> > > Change the code to pass values of the type expected by the callee.
> > >
> > > Signed-off-by: Matthias Kaehlcke 
> > > ---
> > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> > >  4 files changed, 14 insertions(+), 8 deletions(-)
> >
> > Ping, any comments on this patch?
>
> I'm not convinced the patch is making things any better really. To
> fix this really properly, I think we'd need to introduce a new enum
> pch_transcoder and thus avoid the confusion of which type of
> transcoder we're talking about. Currently most places expect an
> enum pipe when dealing with PCH transcoders, and enum transcoder
> when dealing with CPU transcoders. But there are some exceptions
> of course.


I don't follow -- these functions take an enum transcoder; what's
wrong about passing what they expect? It seems like what you are
asking for has nothing to do with the warning here...

Stéphane

>
> --
> Ville Syrjälä
> Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Jani Nikula]

On Mon, 08 May 2017, Daniel Vetter  wrote:
> On Fri, May 05, 2017 at 08:40:43PM +0300, Ville Syrjälä wrote:
>> On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
>> > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
>> > 
>> > > In several instances the driver passes an 'enum pipe' value to a
>> > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
>> > > TRANSCODER_x have the same values this doesn't cause functional
>> > > problems. Still it is incorrect and causes clang to generate warnings
>> > > like this:
>> > > 
>> > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
>> > >   conversion from enumeration type 'enum transcoder' to different
>> > >   enumeration type 'enum pipe' [-Wenum-conversion]
>> > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
>> > > 
>> > > Change the code to pass values of the type expected by the callee.
>> > > 
>> > > Signed-off-by: Matthias Kaehlcke 
>> > > ---
>> > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
>> > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
>> > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
>> > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
>> > >  4 files changed, 14 insertions(+), 8 deletions(-)
>> > 
>> > Ping, any comments on this patch?
>> 
>> I'm not convinced the patch is making things any better really. To
>> fix this really properly, I think we'd need to introduce a new enum 
>> pch_transcoder and thus avoid the confusion of which type of
>> transcoder we're talking about. Currently most places expect an 
>> enum pipe when dealing with PCH transcoders, and enum transcoder
>> when dealing with CPU transcoders. But there are some exceptions
>> of course.
>
> enum transcoder is wrong for the pch, that enum is only for cpu
> transcoders introduced in hsw+. PCH should always use enum pipe.

For background, below is the commit message for introduction of enum
transcoder.

> So a patch to switch the enum to enum pipe for all the pch functions
> sounds like the right thing to do here. Plus maybe rename enum transcoder
> to enum cpu_transcoder, but that'd be tons of work. A comment instead
> might be easier ...

The enum pipe conversion might be the right thing to do *if* you must do
something. But I'm not convinced you must. It's a bunch of churn that's
not just purely mechanical conversion.

BR,
Jani.


commit a5c961d1f3a9ab5ba0e5706e866192f8108143fe
Author: Paulo Zanoni 
Date:   Wed Oct 24 15:59:34 2012 -0200

drm/i915: add TRANSCODER_EDP

Before Haswell we used to have the CPU pipes and the PCH transcoders.
We had the same amount of pipes and transcoders, and there was a 1:1
mapping between them. After Haswell what we used to call CPU pipe was
split into CPU pipe and CPU transcoder. So now we have 3 CPU pipes (A,
B and C), 4 CPU transcoders (A, B, C and EDP) and 1 PCH transcoder
(only used for VGA).

For all the outputs except for EDP we have an 1:1 mapping on the CPU
pipes and CPU transcoders, so if you're using CPU pipe A you have to
use CPU transcoder A. When have an eDP output you have to use
transcoder EDP and you can attach this CPU transcoder to any of the 3
CPU pipes. When using VGA you need to select a pair of matching CPU
pipes/transcoders (A/A, B/B, C/C) and you also need to enable/use the
PCH transcoder.

For now we're just creating the cpu_transcoder definitions and setting
cpu_transcoder to TRANSCODER_EDP on DDI eDP code, but none of the
registers was ported to use transcoder instead of pipe. The goal is to
keep the code backwards-compatible since on all cases except when
using eDP we must have pipe == cpu_transcoder.

V2: Comment the haswell_crtc_off chunk, suggested by Damien Lespiau
and Daniel Vetter.

We currently need the haswell_crtc_off chunk because TRANSCODER_EDP
can be used by any CRTC, so when you stop using it you have to stop
saying you're using it, otherwise you may have at some point 2 CRTCs
claiming they're using TRANSCODER_EDP (a disabled CRTC and an enabled
one), then the HW state readout code will get completely confused.

In other words:

Imagine the following case:
  xrandr --output eDP1 --auto --crtc 0
  xrandr --output eDP1 --off
  xrandr --output eDP1 --auto --crtc 2

After the last command you could get a "pipe A assertion failure
(expected off, current on)" because CRTC 0 still claims it's using
TRANSCODER_EDP, so the HW state readout function will read it
(through PIPECONF) and expect it to be off, when it's actually on
because it's being used by CRTC 2.

So when we make "intel_crtc->cpu_transcoder = intel_crtc->pipe" we
make sure we're pointing to our own original CRTC which is certainly
not used by any other CRTC.

Signed-off-by: Paulo Zanoni 

Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Daniel Vetter]

On Fri, May 05, 2017 at 08:40:43PM +0300, Ville Syrjälä wrote:
> On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> > El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> > 
> > > In several instances the driver passes an 'enum pipe' value to a
> > > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
> > > TRANSCODER_x have the same values this doesn't cause functional
> > > problems. Still it is incorrect and causes clang to generate warnings
> > > like this:
> > > 
> > > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> > >   conversion from enumeration type 'enum transcoder' to different
> > >   enumeration type 'enum pipe' [-Wenum-conversion]
> > > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> > > 
> > > Change the code to pass values of the type expected by the callee.
> > > 
> > > Signed-off-by: Matthias Kaehlcke 
> > > ---
> > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> > >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> > >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> > >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> > >  4 files changed, 14 insertions(+), 8 deletions(-)
> > 
> > Ping, any comments on this patch?
> 
> I'm not convinced the patch is making things any better really. To
> fix this really properly, I think we'd need to introduce a new enum 
> pch_transcoder and thus avoid the confusion of which type of
> transcoder we're talking about. Currently most places expect an 
> enum pipe when dealing with PCH transcoders, and enum transcoder
> when dealing with CPU transcoders. But there are some exceptions
> of course.

enum transcoder is wrong for the pch, that enum is only for cpu
transcoders introduced in hsw+. PCH should always use enum pipe.

So a patch to switch the enum to enum pipe for all the pch functions
sounds like the right thing to do here. Plus maybe rename enum transcoder
to enum cpu_transcoder, but that'd be tons of work. A comment instead
might be easier ...
-Daniel
-- 
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Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Matthias Kaehlcke]

Hi,

El Fri, May 05, 2017 at 01:29:32PM -0700 Grant Grundler ha dit:

> On Fri, May 5, 2017 at 1:08 PM, Ville Syrjälä
>  wrote:
> ...
> >> > I'm not convinced the patch is making things any better really. To
> >> > fix this really properly, I think we'd need to introduce a new enum
> >> > pch_transcoder and thus avoid the confusion of which type of
> >> > transcoder we're talking about.

I agree, the patch certainly doesn't improve the confusing use of the enums.

> >> Is an enum better than coding an explicit conversion in an inline function?
> >
> > The point of the enum would be to make it more clear which piece of
> > hardware we're talking to in each case.
> 
> Ah ok - I misunderstood - I thought this was already the case.
> 
> > But this would require going
> > through the entire PCH code and changing things to use the right type
> > in each case. Quite a bit of work with little measurable gain I'd say.
> 
> IMHO, one of the best things that happened to C standard was addition
> of strong type checking. It's helped prevent developers from making
> one class of "stupid mistakes". So while this change wouldn't improve
> performance, it would allow a form of automated correctness checking
> that can be enforced with every patch you get (every time the code
> base is compiled).
> 
> In other words, the gain isn't currently measurable the same way
> performance is but I believe it's worth doing.  Given the number of
> typedefs and enums in kernel code, I suspect most kernel developers
> would agree.

I also think that proper use of enums is an additional line of defense
against "stupid mistakes". While weeding out these warnings in
different drivers I came across a few cases were the code was working
out of sheer luck because the (unintentionally) mismatched enums
resolved to the same value.

Cheers

Matthias

> >> Then the code can do some sanity checking as well. Something like:
> >>
> >> enum transcoder pch_to_cpu_enum(enum pipe)
> >> {
> >> WARN_ON(pipe > FOO);
> >> return (enum transcoder) pipe;
> >> }
> >
> > That would have to be called pipe_to_pch_transcoder() or something like
> > that.
> >
> >>
> >> > Currently most places expect an
> >> > enum pipe when dealing with PCH transcoders, and enum transcoder
> >> > when dealing with CPU transcoders. But there are some exceptions
> >> > of course.
> >>
> >> cheers,
> >> grant
> >> >
> >
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Grant Grundler]

On Fri, May 5, 2017 at 1:08 PM, Ville Syrjälä
 wrote:
...
>> > I'm not convinced the patch is making things any better really. To
>> > fix this really properly, I think we'd need to introduce a new enum
>> > pch_transcoder and thus avoid the confusion of which type of
>> > transcoder we're talking about.
>>
>> Is an enum better than coding an explicit conversion in an inline function?
>
> The point of the enum would be to make it more clear which piece of
> hardware we're talking to in each case.

Ah ok - I misunderstood - I thought this was already the case.

> But this would require going
> through the entire PCH code and changing things to use the right type
> in each case. Quite a bit of work with little measurable gain I'd say.

IMHO, one of the best things that happened to C standard was addition
of strong type checking. It's helped prevent developers from making
one class of "stupid mistakes". So while this change wouldn't improve
performance, it would allow a form of automated correctness checking
that can be enforced with every patch you get (every time the code
base is compiled).

In other words, the gain isn't currently measurable the same way
performance is but I believe it's worth doing.  Given the number of
typedefs and enums in kernel code, I suspect most kernel developers
would agree.

cheers,
grant



>
>> Then the code can do some sanity checking as well. Something like:
>>
>> enum transcoder pch_to_cpu_enum(enum pipe)
>> {
>> WARN_ON(pipe > FOO);
>> return (enum transcoder) pipe;
>> }
>
> That would have to be called pipe_to_pch_transcoder() or something like
> that.
>
>>
>> > Currently most places expect an
>> > enum pipe when dealing with PCH transcoders, and enum transcoder
>> > when dealing with CPU transcoders. But there are some exceptions
>> > of course.
>>
>> cheers,
>> grant
>> >
>> > --
>> > Ville Syrjälä
>> > Intel OTC
>
> --
> Ville Syrjälä
> Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Ville Syrjälä]

On Fri, May 05, 2017 at 12:12:49PM -0700, Grant Grundler wrote:
> On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
>  wrote:
> > On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> >> El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> >>
> >> > In several instances the driver passes an 'enum pipe' value to a
> >> > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
> >> > TRANSCODER_x have the same values this doesn't cause functional
> >> > problems. Still it is incorrect and causes clang to generate warnings
> >> > like this:
> >> >
> >> > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> >> >   conversion from enumeration type 'enum transcoder' to different
> >> >   enumeration type 'enum pipe' [-Wenum-conversion]
> >> > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> >> >
> >> > Change the code to pass values of the type expected by the callee.
> >> >
> >> > Signed-off-by: Matthias Kaehlcke 
> >> > ---
> >> >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> >> >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> >> >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> >> >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> >> >  4 files changed, 14 insertions(+), 8 deletions(-)
> >>
> >> Ping, any comments on this patch?
> >
> > I'm not convinced the patch is making things any better really. To
> > fix this really properly, I think we'd need to introduce a new enum
> > pch_transcoder and thus avoid the confusion of which type of
> > transcoder we're talking about.
> 
> Is an enum better than coding an explicit conversion in an inline function?

The point of the enum would be to make it more clear which piece of
hardware we're talking to in each case. But this would require going
through the entire PCH code and changing things to use the right type
in each case. Quite a bit of work with little measurable gain I'd say.

> Then the code can do some sanity checking as well. Something like:
> 
> enum transcoder pch_to_cpu_enum(enum pipe)
> {
> WARN_ON(pipe > FOO);
> return (enum transcoder) pipe;
> }

That would have to be called pipe_to_pch_transcoder() or something like
that.

> 
> > Currently most places expect an
> > enum pipe when dealing with PCH transcoders, and enum transcoder
> > when dealing with CPU transcoders. But there are some exceptions
> > of course.
> 
> cheers,
> grant
> >
> > --
> > Ville Syrjälä
> > Intel OTC

-- 
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Grant Grundler]

On Fri, May 5, 2017 at 10:40 AM, Ville Syrjälä
 wrote:
> On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
>> El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
>>
>> > In several instances the driver passes an 'enum pipe' value to a
>> > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
>> > TRANSCODER_x have the same values this doesn't cause functional
>> > problems. Still it is incorrect and causes clang to generate warnings
>> > like this:
>> >
>> > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
>> >   conversion from enumeration type 'enum transcoder' to different
>> >   enumeration type 'enum pipe' [-Wenum-conversion]
>> > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
>> >
>> > Change the code to pass values of the type expected by the callee.
>> >
>> > Signed-off-by: Matthias Kaehlcke 
>> > ---
>> >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
>> >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
>> >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
>> >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
>> >  4 files changed, 14 insertions(+), 8 deletions(-)
>>
>> Ping, any comments on this patch?
>
> I'm not convinced the patch is making things any better really. To
> fix this really properly, I think we'd need to introduce a new enum
> pch_transcoder and thus avoid the confusion of which type of
> transcoder we're talking about.

Is an enum better than coding an explicit conversion in an inline function?
Then the code can do some sanity checking as well. Something like:

enum transcoder pch_to_cpu_enum(enum pipe)
{
WARN_ON(pipe > FOO);
return (enum transcoder) pipe;
}

> Currently most places expect an
> enum pipe when dealing with PCH transcoders, and enum transcoder
> when dealing with CPU transcoders. But there are some exceptions
> of course.

cheers,
grant
>
> --
> Ville Syrjälä
> Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Ville Syrjälä]

On Fri, May 05, 2017 at 10:26:36AM -0700, Matthias Kaehlcke wrote:
> El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:
> 
> > In several instances the driver passes an 'enum pipe' value to a
> > function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
> > TRANSCODER_x have the same values this doesn't cause functional
> > problems. Still it is incorrect and causes clang to generate warnings
> > like this:
> > 
> > drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
> >   conversion from enumeration type 'enum transcoder' to different
> >   enumeration type 'enum pipe' [-Wenum-conversion]
> > assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> > 
> > Change the code to pass values of the type expected by the callee.
> > 
> > Signed-off-by: Matthias Kaehlcke 
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> >  drivers/gpu/drm/i915/intel_dp.c  | 6 --
> >  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
> >  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
> >  4 files changed, 14 insertions(+), 8 deletions(-)
> 
> Ping, any comments on this patch?

I'm not convinced the patch is making things any better really. To
fix this really properly, I think we'd need to introduce a new enum 
pch_transcoder and thus avoid the confusion of which type of
transcoder we're talking about. Currently most places expect an 
enum pipe when dealing with PCH transcoders, and enum transcoder
when dealing with CPU transcoders. But there are some exceptions
of course.

-- 
Ville Syrjälä
Intel OTC
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Re: [Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Matthias Kaehlcke]

El Thu, Apr 20, 2017 at 02:56:05PM -0700 Matthias Kaehlcke ha dit:

> In several instances the driver passes an 'enum pipe' value to a
> function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
> TRANSCODER_x have the same values this doesn't cause functional
> problems. Still it is incorrect and causes clang to generate warnings
> like this:
> 
> drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
>   conversion from enumeration type 'enum transcoder' to different
>   enumeration type 'enum pipe' [-Wenum-conversion]
> assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
> 
> Change the code to pass values of the type expected by the callee.
> 
> Signed-off-by: Matthias Kaehlcke 
> ---
>  drivers/gpu/drm/i915/intel_display.c | 4 ++--
>  drivers/gpu/drm/i915/intel_dp.c  | 6 --
>  drivers/gpu/drm/i915/intel_hdmi.c| 6 --
>  drivers/gpu/drm/i915/intel_sdvo.c| 6 --
>  4 files changed, 14 insertions(+), 8 deletions(-)

Ping, any comments on this patch?

(also excuses for the unintended use of the RESEND tag)

Cheers

Matthias
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[Intel-gfx] [PATCH RESEND] drm/i915: Fix pipe/transcoder enum mismatches

[Matthias Kaehlcke]

In several instances the driver passes an 'enum pipe' value to a
function expecting an 'enum transcoder' and viceversa. Since PIPE_x and
TRANSCODER_x have the same values this doesn't cause functional
problems. Still it is incorrect and causes clang to generate warnings
like this:

drivers/gpu/drm/i915/intel_display.c:1844:34: warning: implicit
  conversion from enumeration type 'enum transcoder' to different
  enumeration type 'enum pipe' [-Wenum-conversion]
assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);

Change the code to pass values of the type expected by the callee.

Signed-off-by: Matthias Kaehlcke 
---
 drivers/gpu/drm/i915/intel_display.c | 4 ++--
 drivers/gpu/drm/i915/intel_dp.c  | 6 --
 drivers/gpu/drm/i915/intel_hdmi.c| 6 --
 drivers/gpu/drm/i915/intel_sdvo.c| 6 --
 4 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c 
b/drivers/gpu/drm/i915/intel_display.c
index ed1f4f272b4f..23484f042fae 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1841,7 +1841,7 @@ static void lpt_enable_pch_transcoder(struct 
drm_i915_private *dev_priv,
 
/* FDI must be feeding us bits for PCH ports */
assert_fdi_tx_enabled(dev_priv, (enum pipe) cpu_transcoder);
-   assert_fdi_rx_enabled(dev_priv, TRANSCODER_A);
+   assert_fdi_rx_enabled(dev_priv, PIPE_A);
 
/* Workaround: set timing override bit. */
val = I915_READ(TRANS_CHICKEN2(PIPE_A));
@@ -4607,7 +4607,7 @@ static void lpt_pch_enable(struct drm_crtc *crtc)
struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
enum transcoder cpu_transcoder = intel_crtc->config->cpu_transcoder;
 
-   assert_pch_transcoder_disabled(dev_priv, TRANSCODER_A);
+   assert_pch_transcoder_disabled(dev_priv, PIPE_A);
 
lpt_program_iclkip(crtc);
 
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index d1670b8afbf5..454c2d3dfdd6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3568,7 +3568,8 @@ intel_dp_link_down(struct intel_dp *intel_dp)
 * doing the workaround. Sweep them under the rug.
 */
intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
-   intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
+   intel_set_pch_fifo_underrun_reporting(dev_priv, TRANSCODER_A,
+ false);
 
/* always enable with pattern 1 (as per spec) */
DP &= ~(DP_PIPEB_SELECT | DP_LINK_TRAIN_MASK);
@@ -3582,7 +3583,8 @@ intel_dp_link_down(struct intel_dp *intel_dp)
 
intel_wait_for_vblank_if_active(dev_priv, PIPE_A);
intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, true);
-   intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
+   intel_set_pch_fifo_underrun_reporting(dev_priv, TRANSCODER_A,
+ true);
}
 
msleep(intel_dp->panel_power_down_delay);
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c 
b/drivers/gpu/drm/i915/intel_hdmi.c
index 24b2fa5b6282..48b1f5d37204 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1153,7 +1153,8 @@ static void intel_disable_hdmi(struct intel_encoder 
*encoder,
 * doing the workaround. Sweep them under the rug.
 */
intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
-   intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
+   intel_set_pch_fifo_underrun_reporting(dev_priv, TRANSCODER_A,
+ false);
 
temp &= ~SDVO_PIPE_B_SELECT;
temp |= SDVO_ENABLE;
@@ -1172,7 +1173,8 @@ static void intel_disable_hdmi(struct intel_encoder 
*encoder,
 
intel_wait_for_vblank_if_active(dev_priv, PIPE_A);
intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, true);
-   intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
+   intel_set_pch_fifo_underrun_reporting(dev_priv, TRANSCODER_A,
+ true);
}
 
intel_hdmi->set_infoframes(>base, false, old_crtc_state, 
old_conn_state);
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c 
b/drivers/gpu/drm/i915/intel_sdvo.c
index 2ad13903a054..0568a9950f7f 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -1462,7 +1462,8 @@ static void intel_disable_sdvo(struct intel_encoder 
*encoder,
 * doing the workaround. Sweep them under the rug.
 */
intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
-