Re: [Intel-gfx] [patch] drm/i915: fix a read size argument

[walter harms]

Am 13.10.2016 10:55, schrieb Dan Carpenter:
> We want to read 3 bytes here, but because the parenthesis are in the
> wrong place we instead read:
> 
>   sizeof(intel_dp->edp_dpcd) == sizeof(intel_dp->edp_dpcd)
> 
> which is one byte.
> 
> Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only 
> once on eDP")
> Signed-off-by: Dan Carpenter 
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 14a3cf0..ee8aa95 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3551,8 +3551,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
>   /* Read the eDP Display control capabilities registers */
>   if ((intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & 
> DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
>   drm_dp_dpcd_read(_dp->aux, DP_EDP_DPCD_REV,
> -  intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd) ==
> -  sizeof(intel_dp->edp_dpcd)))
> +  intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
> +  sizeof(intel_dp->edp_dpcd))



perhaps we can morph that into something more readable ? I would suggest:


if (intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & DP_DPCD_DISPLAY_CONTROL_CAPABLE)
  {
size_t size=sizeof(intel_dp->edp_dpcd); /* == EDP_DISPLAY_CTL_CAP_SIZE */
int ret;

ret=drm_dp_dpcd_read(_dp->aux, 
DP_EDP_DPCD_REV,intel_dp->edp_dpcd,size);  

if (ret != size )
..

 }

this way it improves readability and reduces line length.


>   DRM_DEBUG_KMS("EDP DPCD : %*ph\n", (int) 
> sizeof(intel_dp->edp_dpcd),
> intel_dp->edp_dpcd);
>  
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Re: [Intel-gfx] [patch] drm/i915: fix a read size argument

[Jani Nikula]

On Thu, 13 Oct 2016, walter harms  wrote:
> Am 13.10.2016 10:55, schrieb Dan Carpenter:
>> We want to read 3 bytes here, but because the parenthesis are in the
>> wrong place we instead read:
>> 
>>  sizeof(intel_dp->edp_dpcd) == sizeof(intel_dp->edp_dpcd)
>> 
>> which is one byte.
>> 
>> Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only 
>> once on eDP")
>> Signed-off-by: Dan Carpenter 

Dan, good catch, thank you. Luckily we only really use the first byte
currently...

Cc: 

>> diff --git a/drivers/gpu/drm/i915/intel_dp.c 
>> b/drivers/gpu/drm/i915/intel_dp.c
>> index 14a3cf0..ee8aa95 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -3551,8 +3551,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
>>  /* Read the eDP Display control capabilities registers */
>>  if ((intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & 
>> DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
>>  drm_dp_dpcd_read(_dp->aux, DP_EDP_DPCD_REV,
>> - intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd) ==
>> - sizeof(intel_dp->edp_dpcd)))
>> + intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
>> + sizeof(intel_dp->edp_dpcd))
>
>
>
> perhaps we can morph that into something more readable ? I would suggest:
>
>
> if (intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & 
> DP_DPCD_DISPLAY_CONTROL_CAPABLE)
>   {
> size_t size=sizeof(intel_dp->edp_dpcd); /* == EDP_DISPLAY_CTL_CAP_SIZE */
> int ret;  
>
> ret=drm_dp_dpcd_read(_dp->aux, 
> DP_EDP_DPCD_REV,intel_dp->edp_dpcd,size);
>
> if (ret != size )
> ..
>
>  }
>
> this way it improves readability and reduces line length.

Not convinced, let's just take the simple brace fix now.

BR,
Jani.


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Re: [Intel-gfx] [patch] drm/i915: fix a read size argument

[Dan Carpenter]

On Thu, Oct 13, 2016 at 10:01:03AM +0100, Chris Wilson wrote:
> On Thu, Oct 13, 2016 at 11:55:08AM +0300, Dan Carpenter wrote:
> > We want to read 3 bytes here, but because the parenthesis are in the
> > wrong place we instead read:
> > 
> > sizeof(intel_dp->edp_dpcd) == sizeof(intel_dp->edp_dpcd)
> > 
> > which is one byte.
> > 
> > Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only 
> > once on eDP")
> > Signed-off-by: Dan Carpenter 
> 
> Oops, does smatch catch this?

Yeah.  It does.

regards,
dan carpenter

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Re: [Intel-gfx] [patch] drm/i915: fix a read size argument

[Eric Engestrom]

On Thu, Oct 13, 2016 at 11:55:08AM +0300, Dan Carpenter wrote:
> We want to read 3 bytes here, but because the parenthesis are in the
> wrong place we instead read:
> 
>   sizeof(intel_dp->edp_dpcd) == sizeof(intel_dp->edp_dpcd)
> 
> which is one byte.
> 
> Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only 
> once on eDP")
> Signed-off-by: Dan Carpenter 

Good catch!  What tool did you use to find it, or did you find it by
inspection?
Reviewed-by: Eric Engestrom 

(btw, there's a missing `---` here, between the commit msg and the diff)

> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 14a3cf0..ee8aa95 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3551,8 +3551,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
>   /* Read the eDP Display control capabilities registers */
>   if ((intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & 
> DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
>   drm_dp_dpcd_read(_dp->aux, DP_EDP_DPCD_REV,
> -  intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd) ==
> -  sizeof(intel_dp->edp_dpcd)))
> +  intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
> +  sizeof(intel_dp->edp_dpcd))
>   DRM_DEBUG_KMS("EDP DPCD : %*ph\n", (int) 
> sizeof(intel_dp->edp_dpcd),
> intel_dp->edp_dpcd);
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Re: [Intel-gfx] [patch] drm/i915: fix a read size argument

[Chris Wilson]

On Thu, Oct 13, 2016 at 11:55:08AM +0300, Dan Carpenter wrote:
> We want to read 3 bytes here, but because the parenthesis are in the
> wrong place we instead read:
> 
>   sizeof(intel_dp->edp_dpcd) == sizeof(intel_dp->edp_dpcd)
> 
> which is one byte.
> 
> Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only 
> once on eDP")
> Signed-off-by: Dan Carpenter 

Oops, does smatch catch this? I don't recall seeing the complaint in
recent runs?

Reviewed-by: Chris Wilson 
-Chris

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[Intel-gfx] [patch] drm/i915: fix a read size argument

[Dan Carpenter]

We want to read 3 bytes here, but because the parenthesis are in the
wrong place we instead read:

sizeof(intel_dp->edp_dpcd) == sizeof(intel_dp->edp_dpcd)

which is one byte.

Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only once 
on eDP")
Signed-off-by: Dan Carpenter 

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 14a3cf0..ee8aa95 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3551,8 +3551,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
/* Read the eDP Display control capabilities registers */
if ((intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & 
DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
drm_dp_dpcd_read(_dp->aux, DP_EDP_DPCD_REV,
-intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd) ==
-sizeof(intel_dp->edp_dpcd)))
+intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
+sizeof(intel_dp->edp_dpcd))
DRM_DEBUG_KMS("EDP DPCD : %*ph\n", (int) 
sizeof(intel_dp->edp_dpcd),
  intel_dp->edp_dpcd);
 
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