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

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Date: Wed, 5 Jun 2024 02:58:46 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
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 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.

> 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__));

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

-- 
With best wishes
Dmitry