Re: dw_mmc: Does anyone use multiple slots?

[Doug Anderson]

Hi,

On Thu, Aug 8, 2013 at 8:18 PM, Seungwon Jeon  wrote:
> On Fri, August 09, 2013, Chris Ball wrote:
>> On Fri, Aug 09 2013, Olof Johansson wrote:
>> > On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson  wrote:
>> >
>> >> I guess my overall question is: if there are no actual implementations
>> >> of multislot, shouldn't we kill it and simplify the code a whole lot?
>> >> If someone out there has a real multislot device they can step back in
>> >> and do it more correctly?
>> >>
>> >> Of course we need to find someone to actually go through and do the
>> >> killing of multislot, but finding that person might be easier if there
>> >> was some agreement that it was good to do.
>> >
>> > There clearly seems to be no in-tree users of multislot. If someone
>> > new comes in, we have the code in the history and can revert the
>> > removal (or at least use it as reference for re-introduction).
>> >
>> > I vote for removing it. It adds really annoying complexity for
>> > something that nobody uses.
>>
>> I agree with Olof, for what it's worth.  (The maintainers of the
>> driver are Jaehoon and Seungwon, though.)
>
> I feel like there is no actual use case for that though origin Synopsys IP 
> supports.
> Multi-slot  might be not useful in terms of performance because shared bus 
> should be allowed.
> (At least this is the way I see it, though)
> As Exynos's host does so, other hosts which are introduced in Linux seems use 
> one card per host.
> If it's really not found now, I could agree on this topic.

This all sounds very promising.  Certainly we should wait a little
longer to see if others find / respond to this thread, but otherwise
we can go ahead?

It's possible to do this in somewhat small steps.  I think the first
step is to remove num_slots and remove all loops over num_slots.  That
actually sounds pretty easy/small, though it will touch a lot of code.
 After that we can try to move things out of the separate slot
structure, I think.  That might be a bit of a bigger change.  I can
keep that as a back burner task, but I wouldn't object at all to
someone else doing it!  ;)

The big question, though, is what to do about device tree bindings
(cringe).  Really bus-width, wp-gpios, and disable-wp ought to be
promoted up and we should remove the "slot" subnode.  ...but that of
course breaks the stable API.

-Doug
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Re: dw_mmc: Does anyone use multiple slots?

[Doug Anderson]

Hi,

On Thu, Aug 8, 2013 at 8:18 PM, Seungwon Jeon tgih@samsung.com wrote:
 On Fri, August 09, 2013, Chris Ball wrote:
 On Fri, Aug 09 2013, Olof Johansson wrote:
  On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson diand...@google.com wrote:
 
  I guess my overall question is: if there are no actual implementations
  of multislot, shouldn't we kill it and simplify the code a whole lot?
  If someone out there has a real multislot device they can step back in
  and do it more correctly?
 
  Of course we need to find someone to actually go through and do the
  killing of multislot, but finding that person might be easier if there
  was some agreement that it was good to do.
 
  There clearly seems to be no in-tree users of multislot. If someone
  new comes in, we have the code in the history and can revert the
  removal (or at least use it as reference for re-introduction).
 
  I vote for removing it. It adds really annoying complexity for
  something that nobody uses.

 I agree with Olof, for what it's worth.  (The maintainers of the
 driver are Jaehoon and Seungwon, though.)

 I feel like there is no actual use case for that though origin Synopsys IP 
 supports.
 Multi-slot  might be not useful in terms of performance because shared bus 
 should be allowed.
 (At least this is the way I see it, though)
 As Exynos's host does so, other hosts which are introduced in Linux seems use 
 one card per host.
 If it's really not found now, I could agree on this topic.

This all sounds very promising.  Certainly we should wait a little
longer to see if others find / respond to this thread, but otherwise
we can go ahead?

It's possible to do this in somewhat small steps.  I think the first
step is to remove num_slots and remove all loops over num_slots.  That
actually sounds pretty easy/small, though it will touch a lot of code.
 After that we can try to move things out of the separate slot
structure, I think.  That might be a bit of a bigger change.  I can
keep that as a back burner task, but I wouldn't object at all to
someone else doing it!  ;)

The big question, though, is what to do about device tree bindings
(cringe).  Really bus-width, wp-gpios, and disable-wp ought to be
promoted up and we should remove the slot subnode.  ...but that of
course breaks the stable API.

-Doug
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RE: dw_mmc: Does anyone use multiple slots?

[Seungwon Jeon]

On Fri, August 09, 2013, Chris Ball wrote:
> On Fri, Aug 09 2013, Olof Johansson wrote:
> > On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson  wrote:
> >
> >> I guess my overall question is: if there are no actual implementations
> >> of multislot, shouldn't we kill it and simplify the code a whole lot?
> >> If someone out there has a real multislot device they can step back in
> >> and do it more correctly?
> >>
> >> Of course we need to find someone to actually go through and do the
> >> killing of multislot, but finding that person might be easier if there
> >> was some agreement that it was good to do.
> >
> > There clearly seems to be no in-tree users of multislot. If someone
> > new comes in, we have the code in the history and can revert the
> > removal (or at least use it as reference for re-introduction).
> >
> > I vote for removing it. It adds really annoying complexity for
> > something that nobody uses.
> 
> I agree with Olof, for what it's worth.  (The maintainers of the
> driver are Jaehoon and Seungwon, though.)

I feel like there is no actual use case for that though origin Synopsys IP 
supports.
Multi-slot  might be not useful in terms of performance because shared bus 
should be allowed.
(At least this is the way I see it, though)
As Exynos's host does so, other hosts which are introduced in Linux seems use 
one card per host.
If it's really not found now, I could agree on this topic.

Thanks,
Seungwon Jeon

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Re: dw_mmc: Does anyone use multiple slots?

[Chris Ball]

Hi,

On Fri, Aug 09 2013, Olof Johansson wrote:
> On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson  wrote:
>
>> I guess my overall question is: if there are no actual implementations
>> of multislot, shouldn't we kill it and simplify the code a whole lot?
>> If someone out there has a real multislot device they can step back in
>> and do it more correctly?
>>
>> Of course we need to find someone to actually go through and do the
>> killing of multislot, but finding that person might be easier if there
>> was some agreement that it was good to do.
>
> There clearly seems to be no in-tree users of multislot. If someone
> new comes in, we have the code in the history and can revert the
> removal (or at least use it as reference for re-introduction).
>
> I vote for removing it. It adds really annoying complexity for
> something that nobody uses.

I agree with Olof, for what it's worth.  (The maintainers of the
driver are Jaehoon and Seungwon, though.)

Thanks,

- Chris.
-- 
Chris Ball  
--
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Re: dw_mmc: Does anyone use multiple slots?

[Olof Johansson]

On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson  wrote:

> I guess my overall question is: if there are no actual implementations
> of multislot, shouldn't we kill it and simplify the code a whole lot?
> If someone out there has a real multislot device they can step back in
> and do it more correctly?
>
> Of course we need to find someone to actually go through and do the
> killing of multislot, but finding that person might be easier if there
> was some agreement that it was good to do.

There clearly seems to be no in-tree users of multislot. If someone
new comes in, we have the code in the history and can revert the
removal (or at least use it as reference for re-introduction).

I vote for removing it. It adds really annoying complexity for
something that nobody uses.


-Olof
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the body of a message to majord...@vger.kernel.org
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Re: dw_mmc: Does anyone use multiple slots?

[Olof Johansson]

On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson diand...@google.com wrote:

 I guess my overall question is: if there are no actual implementations
 of multislot, shouldn't we kill it and simplify the code a whole lot?
 If someone out there has a real multislot device they can step back in
 and do it more correctly?

 Of course we need to find someone to actually go through and do the
 killing of multislot, but finding that person might be easier if there
 was some agreement that it was good to do.

There clearly seems to be no in-tree users of multislot. If someone
new comes in, we have the code in the history and can revert the
removal (or at least use it as reference for re-introduction).

I vote for removing it. It adds really annoying complexity for
something that nobody uses.


-Olof
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the body of a message to majord...@vger.kernel.org
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Please read the FAQ at  http://www.tux.org/lkml/

Re: dw_mmc: Does anyone use multiple slots?

[Chris Ball]

Hi,

On Fri, Aug 09 2013, Olof Johansson wrote:
 On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson diand...@google.com wrote:

 I guess my overall question is: if there are no actual implementations
 of multislot, shouldn't we kill it and simplify the code a whole lot?
 If someone out there has a real multislot device they can step back in
 and do it more correctly?

 Of course we need to find someone to actually go through and do the
 killing of multislot, but finding that person might be easier if there
 was some agreement that it was good to do.

 There clearly seems to be no in-tree users of multislot. If someone
 new comes in, we have the code in the history and can revert the
 removal (or at least use it as reference for re-introduction).

 I vote for removing it. It adds really annoying complexity for
 something that nobody uses.

I agree with Olof, for what it's worth.  (The maintainers of the
driver are Jaehoon and Seungwon, though.)

Thanks,

- Chris.
-- 
Chris Ball   c...@laptop.org   http://printf.net/
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the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

RE: dw_mmc: Does anyone use multiple slots?

[Seungwon Jeon]

On Fri, August 09, 2013, Chris Ball wrote:
 On Fri, Aug 09 2013, Olof Johansson wrote:
  On Thu, Aug 8, 2013 at 5:16 PM, Doug Anderson diand...@google.com wrote:
 
  I guess my overall question is: if there are no actual implementations
  of multislot, shouldn't we kill it and simplify the code a whole lot?
  If someone out there has a real multislot device they can step back in
  and do it more correctly?
 
  Of course we need to find someone to actually go through and do the
  killing of multislot, but finding that person might be easier if there
  was some agreement that it was good to do.
 
  There clearly seems to be no in-tree users of multislot. If someone
  new comes in, we have the code in the history and can revert the
  removal (or at least use it as reference for re-introduction).
 
  I vote for removing it. It adds really annoying complexity for
  something that nobody uses.
 
 I agree with Olof, for what it's worth.  (The maintainers of the
 driver are Jaehoon and Seungwon, though.)

I feel like there is no actual use case for that though origin Synopsys IP 
supports.
Multi-slot  might be not useful in terms of performance because shared bus 
should be allowed.
(At least this is the way I see it, though)
As Exynos's host does so, other hosts which are introduced in Linux seems use 
one card per host.
If it's really not found now, I could agree on this topic.

Thanks,
Seungwon Jeon

--
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the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/