[PATCH] drm/amd/display: remove redundant check

[PATCH] drm/amd/display: remove redundant check

[José Pekkarinen]

This patch addresses the following warning spotted by
using coccinelle where the case checked does the same
than the else case.

drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)

Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
---
 .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
index ecea008f19d3..d940dfa5ae43 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
@@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
 	} else if (AllowForPStateChangeOrStutterInVBlankFinal == dm_prefetch_support_uclk_fclk_and_stutter) {
 		*MinPrefetchMode = 0;
 		*MaxPrefetchMode = 0;
-	} else if (AllowForPStateChangeOrStutterInVBlankFinal ==
-			dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
-		*MinPrefetchMode = 0;
-		*MaxPrefetchMode = 3;
 	} else {
 		*MinPrefetchMode = 0;
 		*MaxPrefetchMode = 3;
-- 
2.39.2

Re: [PATCH] drm/amd/display: remove redundant check

[Aurabindo Pillai]

On 10/29/2023 8:44 AM, José Pekkarinen wrote:
> This patch addresses the following warning spotted by
> using coccinelle where the case checked does the same
> than the else case.
> 
> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)
> 
> Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
> ---
>   .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
> index ecea008f19d3..d940dfa5ae43 100644
> --- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
> +++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
> @@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
>   	} else if (AllowForPStateChangeOrStutterInVBlankFinal == dm_prefetch_support_uclk_fclk_and_stutter) {
>   		*MinPrefetchMode = 0;
>   		*MaxPrefetchMode = 0;
> -	} else if (AllowForPStateChangeOrStutterInVBlankFinal ==
> -			dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
> -		*MinPrefetchMode = 0;
> -		*MaxPrefetchMode = 3;
>   	} else {
>   		*MinPrefetchMode = 0;
>   		*MaxPrefetchMode = 3;

What tree did you use to generate the patch? On amd-staging-drm-next, 
MaxPrefetchMode is 0 for the second last branch, which is the correct 
one, so this patch isnt needed.

Re: [PATCH] drm/amd/display: remove redundant check

[José Pekkarinen]

On 2023-10-30 15:52, Aurabindo Pillai wrote:
> On 10/29/2023 8:44 AM, José Pekkarinen wrote:
>> This patch addresses the following warning spotted by
>> using coccinelle where the case checked does the same
>> than the else case.
>> 
>> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: 
>> WARNING: possible condition with no effect (if == else)
>> 
>> Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
>> ---
>>   .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 
>> ----
>>   1 file changed, 4 deletions(-)
>> 
>> diff --git 
>> a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c 
>> b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>> index ecea008f19d3..d940dfa5ae43 100644
>> --- 
>> a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>> +++ 
>> b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>> @@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
>>   	} else if (AllowForPStateChangeOrStutterInVBlankFinal == 
>> dm_prefetch_support_uclk_fclk_and_stutter) {
>>   		*MinPrefetchMode = 0;
>>   		*MaxPrefetchMode = 0;
>> -	} else if (AllowForPStateChangeOrStutterInVBlankFinal ==
>> -			dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
>> -		*MinPrefetchMode = 0;
>> -		*MaxPrefetchMode = 3;
>>   	} else {
>>   		*MinPrefetchMode = 0;
>>   		*MaxPrefetchMode = 3;
> 
> What tree did you use to generate the patch? On amd-staging-drm-next,
> MaxPrefetchMode is 0 for the second last branch, which is the correct
> one, so this patch isnt needed.

     I'm using the stable tree, sorry, if it is out of
date just ignore it then.

     Thanks!

     José.

Re: [PATCH] drm/amd/display: remove redundant check

[Aurabindo Pillai]

On 2023-10-30 12:26, José Pekkarinen wrote:
> On 2023-10-30 15:52, Aurabindo Pillai wrote:
>> On 10/29/2023 8:44 AM, José Pekkarinen wrote:
>>> This patch addresses the following warning spotted by
>>> using coccinelle where the case checked does the same
>>> than the else case.
>>>
>>> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)
>>>
>>> Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
>>> ---
>>>   .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
>>>   1 file changed, 4 deletions(-)
>>>
>>> diff --git 
>>> a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c 
>>> b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>>> index ecea008f19d3..d940dfa5ae43 100644
>>> --- 
>>> a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>>> +++ 
>>> b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>>> @@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
>>>       } else if (AllowForPStateChangeOrStutterInVBlankFinal == 
>>> dm_prefetch_support_uclk_fclk_and_stutter) {
>>>           *MinPrefetchMode = 0;
>>>           *MaxPrefetchMode = 0;
>>> -    } else if (AllowForPStateChangeOrStutterInVBlankFinal ==
>>> -            dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
>>> -        *MinPrefetchMode = 0;
>>> -        *MaxPrefetchMode = 3;
>>>       } else {
>>>           *MinPrefetchMode = 0;
>>>           *MaxPrefetchMode = 3;
>>
>> What tree did you use to generate the patch? On amd-staging-drm-next,
>> MaxPrefetchMode is 0 for the second last branch, which is the correct
>> one, so this patch isnt needed.
> 
>      I'm using the stable tree, sorry, if it is out of
> date just ignore it then.
> 
>      Thanks!
> 
>      José.
Actually, you're right - the patch's limited context mislead me, sorry.
But please add the following tag and sent it to stable@vger.kernel.org 
instead:

Fixes: 974ce181 ("drm/amd/display: Add check for PState change in DCN32")

[PATCH] drm/amd/display: remove redundant check

[José Pekkarinen]

This patch addresses the following warning spotted by
using coccinelle where the case checked does the same
than the else case.

drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)

Fixes: 974ce181 ("drm/amd/display: Add check for PState change in DCN32")

Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
---
 .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
index ecea008f19d3..d940dfa5ae43 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
@@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
 	} else if (AllowForPStateChangeOrStutterInVBlankFinal == dm_prefetch_support_uclk_fclk_and_stutter) {
 		*MinPrefetchMode = 0;
 		*MaxPrefetchMode = 0;
-	} else if (AllowForPStateChangeOrStutterInVBlankFinal ==
-			dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
-		*MinPrefetchMode = 0;
-		*MaxPrefetchMode = 3;
 	} else {
 		*MinPrefetchMode = 0;
 		*MaxPrefetchMode = 3;
-- 
2.39.2

[PATCH] drm/amd/display: remove redundant check

[José Pekkarinen]

This patch addresses the following warning spotted by
using coccinelle where the case checked does the same
than the else case.

drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)

Fixes: 974ce181 ("drm/amd/display: Add check for PState change in DCN32")

Cc: stable@vger.kernel.org
Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
---
 .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
index ecea008f19d3..d940dfa5ae43 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
@@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
 	} else if (AllowForPStateChangeOrStutterInVBlankFinal == dm_prefetch_support_uclk_fclk_and_stutter) {
 		*MinPrefetchMode = 0;
 		*MaxPrefetchMode = 0;
-	} else if (AllowForPStateChangeOrStutterInVBlankFinal ==
-			dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
-		*MinPrefetchMode = 0;
-		*MaxPrefetchMode = 3;
 	} else {
 		*MinPrefetchMode = 0;
 		*MaxPrefetchMode = 3;
-- 
2.39.2

Re: [PATCH] drm/amd/display: remove redundant check

[Aurabindo Pillai]

On 2023-10-30 13:17, José Pekkarinen wrote:
> This patch addresses the following warning spotted by
> using coccinelle where the case checked does the same
> than the else case.
> 
> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)
> 
> Fixes: 974ce181 ("drm/amd/display: Add check for PState change in DCN32")
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
> ---
>   .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
> index ecea008f19d3..d940dfa5ae43 100644
> --- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
> +++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
> @@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
>   	} else if (AllowForPStateChangeOrStutterInVBlankFinal == dm_prefetch_support_uclk_fclk_and_stutter) {
>   		*MinPrefetchMode = 0;
>   		*MaxPrefetchMode = 0;
> -	} else if (AllowForPStateChangeOrStutterInVBlankFinal ==
> -			dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
> -		*MinPrefetchMode = 0;
> -		*MaxPrefetchMode = 3;
>   	} else {
>   		*MinPrefetchMode = 0;
>   		*MaxPrefetchMode = 3;

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>

Re: [PATCH] drm/amd/display: remove redundant check

[Greg KH]

On Mon, Oct 30, 2023 at 07:17:48PM +0200, José Pekkarinen wrote:
> This patch addresses the following warning spotted by
> using coccinelle where the case checked does the same
> than the else case.
> 
> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: WARNING: possible condition with no effect (if == else)
> 
> Fixes: 974ce181 ("drm/amd/display: Add check for PState change in DCN32")
> 
> Cc: stable@vger.kernel.org

Why is this relevant for stable?

Re: [PATCH] drm/amd/display: remove redundant check

[José Pekkarinen]

On 2023-10-31 07:48, Greg KH wrote:
> On Mon, Oct 30, 2023 at 07:17:48PM +0200, José Pekkarinen wrote:
>> This patch addresses the following warning spotted by
>> using coccinelle where the case checked does the same
>> than the else case.
>> 
>> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10: 
>> WARNING: possible condition with no effect (if == else)
>> 
>> Fixes: 974ce181 ("drm/amd/display: Add check for PState change in 
>> DCN32")
>> 
>> Cc: stable@vger.kernel.org
> 
> Why is this relevant for stable?

     Hi,

     I was asked to send it for stable because this code
looks different in amd-staging-drm-next, see here.

https://gitlab.freedesktop.org/agd5f/linux/-/blob/amd-staging-drm-next/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c#L4661

     Feel free to let me know if this is wrong, or if I
need to review some other guidelines I may have missed.

     Thanks!

     José.

Re: [PATCH] drm/amd/display: remove redundant check

[Greg KH]

On Tue, Oct 31, 2023 at 01:42:17PM +0200, José Pekkarinen wrote:
> On 2023-10-31 07:48, Greg KH wrote:
> > On Mon, Oct 30, 2023 at 07:17:48PM +0200, José Pekkarinen wrote:
> > > This patch addresses the following warning spotted by
> > > using coccinelle where the case checked does the same
> > > than the else case.
> > > 
> > > drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10:
> > > WARNING: possible condition with no effect (if == else)
> > > 
> > > Fixes: 974ce181 ("drm/amd/display: Add check for PState change in
> > > DCN32")
> > > 
> > > Cc: stable@vger.kernel.org
> > 
> > Why is this relevant for stable?
> 
>     Hi,
> 
>     I was asked to send it for stable because this code
> looks different in amd-staging-drm-next, see here.
> 
> https://gitlab.freedesktop.org/agd5f/linux/-/blob/amd-staging-drm-next/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c#L4661

I don't know what I am looking at, sorry.

>     Feel free to let me know if this is wrong, or if I
> need to review some other guidelines I may have missed.

Please see the list of rules for stable patches:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html

Does "remove code that does nothing" fit here?

thanks,

greg k-h

Re: [PATCH] drm/amd/display: remove redundant check

[José Pekkarinen]

On 2023-10-31 14:20, Greg KH wrote:
> On Tue, Oct 31, 2023 at 01:42:17PM +0200, José Pekkarinen wrote:
>> On 2023-10-31 07:48, Greg KH wrote:
>> > On Mon, Oct 30, 2023 at 07:17:48PM +0200, José Pekkarinen wrote:
>> > > This patch addresses the following warning spotted by
>> > > using coccinelle where the case checked does the same
>> > > than the else case.
>> > >
>> > > drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10:
>> > > WARNING: possible condition with no effect (if == else)
>> > >
>> > > Fixes: 974ce181 ("drm/amd/display: Add check for PState change in
>> > > DCN32")
>> > >
>> > > Cc: stable@vger.kernel.org
>> >
>> > Why is this relevant for stable?
>> 
>>     Hi,
>> 
>>     I was asked to send it for stable because this code
>> looks different in amd-staging-drm-next, see here.
>> 
>> https://gitlab.freedesktop.org/agd5f/linux/-/blob/amd-staging-drm-next/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c#L4661
> 
> I don't know what I am looking at, sorry.
> 
>>     Feel free to let me know if this is wrong, or if I
>> need to review some other guidelines I may have missed.
> 
> Please see the list of rules for stable patches:
>     
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> 
> Does "remove code that does nothing" fit here?

     Yep, it is a trivial fix which compilers should be able
to optimize, so no real benefit to the user. Sorry Greg!

     José.

Re: [PATCH] drm/amd/display: remove redundant check

[Aurabindo Pillai]

On 2023-10-31 08:32, José Pekkarinen wrote:
> On 2023-10-31 14:20, Greg KH wrote:
>> On Tue, Oct 31, 2023 at 01:42:17PM +0200, José Pekkarinen wrote:
>>> On 2023-10-31 07:48, Greg KH wrote:
>>> > On Mon, Oct 30, 2023 at 07:17:48PM +0200, José Pekkarinen wrote:
>>> > > This patch addresses the following warning spotted by
>>> > > using coccinelle where the case checked does the same
>>> > > than the else case.
>>> > >
>>> > > 
>>> drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10:
>>> > > WARNING: possible condition with no effect (if == else)
>>> > >
>>> > > Fixes: 974ce181 ("drm/amd/display: Add check for PState change in
>>> > > DCN32")
>>> > >
>>> > > Cc: stable@vger.kernel.org
>>> >
>>> > Why is this relevant for stable?
>>>
>>>     Hi,
>>>
>>>     I was asked to send it for stable because this code
>>> looks different in amd-staging-drm-next, see here.
>>>
>>> https://gitlab.freedesktop.org/agd5f/linux/-/blob/amd-staging-drm-next/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c#L4661
>>
>> I don't know what I am looking at, sorry.
>>
>>>     Feel free to let me know if this is wrong, or if I
>>> need to review some other guidelines I may have missed.
>>
>> Please see the list of rules for stable patches:
>> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>>
>> Does "remove code that does nothing" fit here?
> 
>      Yep, it is a trivial fix which compilers should be able
> to optimize, so no real benefit to the user. Sorry Greg!
> 
>      José.

Hi Greg,

Sorry, I asked José to send it to stable because I realized the patch 
listed in the fixes tag wasnt quite needed on stable. Patch from José 
effectively removes it.

I hope that clears the context. But there is no impact whether you apply 
José's patch or not, so we're good either way.