linux-kernel - Re: [PATCH] drm/msm/a6xx: use __always_unused to fix compiler warnings for gen7

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Date: Tue, 4 Jun 2024 17:13:27 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <freedreno@...ts.freedesktop.org>, Rob Clark <robdclark@...il.com>,
        "Sean
 Paul" <sean@...rly.run>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "Marijn
 Suijten" <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Connor Abbott <cwabbott0@...il.com>, <dri-devel@...ts.freedesktop.org>,
        <seanpaul@...omium.org>, <quic_jesszhan@...cinc.com>,
        Rob Clark <robdclark@...omium.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm/a6xx: use __always_unused to fix compiler
 warnings for gen7_* includes



On 6/4/2024 4:58 PM, Dmitry Baryshkov wrote:
> On Tue, Jun 04, 2024 at 02:51:04PM -0700, Abhinav Kumar wrote:
>> GCC diagnostic pragma method throws below warnings in some of the versions
>>
>> drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:16:9: warning: unknown option after '#pragma GCC diagnostic' kind [-Wpragmas]
>>   #pragma GCC diagnostic ignored "-Wunused-const-variable"
>>           ^
>> In file included from drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:18:0:
>> drivers/gpu/drm/msm/adreno/adreno_gen7_0_0_snapshot.h:924:19: warning: 'gen7_0_0_external_core_regs__always_unused' defined but not used [-Wunused-variable]
>>   static const u32 *gen7_0_0_external_core_regs__always_unused[] = {
>>                     ^
> 
> I don't see this symbol in upstream.
> 

This was a C&P mistake. Instead of pasting the warning message from the 
default msm-next, I pasted the warning message from one of my trial runs 
(a bad one). I will fix the commit message when I post a v2.

The correct warnings are:

drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:16:9: warning: unknown 
option after '#pragma GCC diagnostic' kind [-Wpragmas]
  #pragma GCC diagnostic ignored "-Wunused-const-variable"
          ^
In file included from drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:18:0:
drivers/gpu/drm/msm/adreno/adreno_gen7_0_0_snapshot.h:924:19: warning: 
'gen7_0_0_external_core_regs' defined but not used [-Wunused-variable]
  static const u32 *gen7_0_0_external_core_regs[] = {
                    ^
In file included from drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:19:0:
drivers/gpu/drm/msm/adreno/adreno_gen7_2_0_snapshot.h:748:19: warning: 
'gen7_2_0_external_core_regs' defined but not used [-Wunused-variable]
  static const u32 *gen7_2_0_external_core_regs[] = {
                    ^
In file included from drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:20:0:
drivers/gpu/drm/msm/adreno/adreno_gen7_9_0_snapshot.h:1188:43: warning: 
'gen7_9_0_sptp_clusters' defined but not used [-Wunused-variable]
  static struct gen7_sptp_cluster_registers gen7_9_0_sptp_clusters[] = {
                                            ^
drivers/gpu/drm/msm/adreno/adreno_gen7_9_0_snapshot.h:1438:19: warning: 
'gen7_9_0_external_core_regs' defined but not used [-Wunused-variable]
  static const u32 *gen7_9_0_external_core_regs[] = {


>> In file included from drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:19:0:
>> drivers/gpu/drm/msm/adreno/adreno_gen7_2_0_snapshot.h:748:19: warning: 'gen7_2_0_external_core_regs' defined but not used [-Wunused-variable]
>>   static const u32 *gen7_2_0_external_core_regs[] = {
>>                     ^
>> In file included from drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c:20:0:
>> drivers/gpu/drm/msm/adreno/adreno_gen7_9_0_snapshot.h:1188:43: warning: 'gen7_9_0_sptp_clusters' defined but not used [-Wunused-variable]
>>   static struct gen7_sptp_cluster_registers gen7_9_0_sptp_clusters[] = {
>>                                             ^
>> drivers/gpu/drm/msm/adreno/adreno_gen7_9_0_snapshot.h:1438:19: warning: 'gen7_9_0_external_core_regs' defined but not used [-Wunused-variable]
>>   static const u32 *gen7_9_0_external_core_regs[] = {
>>
>> Remove GCC dependency by using __always_unused for the unused gen7_* includes.
>>
>> Fixes: 64d6255650d4 ("drm/msm: More fully implement devcoredump for a7xx")
>> Suggested-by: Rob Clark <robdclark@...omium.org>
>> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
>> ---
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c | 13 ++++---------
>>   1 file changed, 4 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
>> index 0a7717a4fc2f..62ca0cf24005 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
>> @@ -8,19 +8,10 @@
>>   #include "a6xx_gpu_state.h"
>>   #include "a6xx_gmu.xml.h"
>>   
>> -/* Ignore diagnostics about register tables that we aren't using yet. We don't
>> - * want to modify these headers too much from their original source.
>> - */
>> -#pragma GCC diagnostic push
>> -#pragma GCC diagnostic ignored "-Wunused-variable"
>> -#pragma GCC diagnostic ignored "-Wunused-const-variable"
>> -
>>   #include "adreno_gen7_0_0_snapshot.h"
>>   #include "adreno_gen7_2_0_snapshot.h"
>>   #include "adreno_gen7_9_0_snapshot.h"
>>   
>> -#pragma GCC diagnostic pop
>> -
>>   struct a6xx_gpu_state_obj {
>>   	const void *handle;
>>   	u32 *data;
>> @@ -1350,6 +1341,10 @@ static void a7xx_get_registers(struct msm_gpu *gpu,
>>   	int index = 0;
>>   	const u32 *pre_crashdumper_regs;
>>   	const struct gen7_reg_list *reglist;
>> +	__always_unused const u32 **external_core_regs7_0_0 = gen7_0_0_external_core_regs;
>> +	__always_unused const u32 **external_core_regs_7_2_0 = gen7_2_0_external_core_regs;
>> +	__always_unused const u32 **external_core_regs_7_9_0 = gen7_9_0_external_core_regs;
>> +	__always_unused struct gen7_sptp_cluster_registers *sptp_gen7 = gen7_9_0_sptp_clusters;
> 
> Wouldn't it be easier to add something like the following to the
> a6xx_gpu_state.c before including the headers:
> 
> static const unsigned int *gen7_0_0_external_core_regs[] __attribute((__unused__));
> static const unsigned int *gen7_2_0_external_core_regs[] __attribute((__unused__));
> static const unsigned int *gen7_9_0_external_core_regs[] __attribute((__unused__));
> 

Ack, this works too and its cleaner. let me push it this way. Thanks.

>>   
>>   	if (adreno_is_a730(adreno_gpu)) {
>>   		reglist = gen7_0_0_reg_list;
>> -- 
>> 2.44.0
>>
>