[PATCH] drm/msm: Fix removal of valid error case when checking speed_bin

[PATCH] drm/msm: Fix removal of valid error case when checking speed_bin

[John Stultz]

Commit 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to
access outside valid memory"), reworked the nvmem reading of
"speed_bin", but in doing so dropped handling of the -ENOENT
case which was previously documented as "fine".

That change resulted in the db845c board display to fail to
start, with the following error:

adreno 5000000.gpu: [drm:a6xx_gpu_init] *ERROR* failed to read speed-bin (-2). Some OPPs may not be supported by hardware

Thus, this patch simply re-adds the ENOENT handling so the lack
of the speed_bin entry isn't fatal for display, and gets things
working on db845c.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Jordan Crouse <jcrouse@codeaurora.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: YongQin Liu <yongqin.liu@linaro.org>
Reported-by: YongQin Liu <yongqin.liu@linaro.org>
Fixes: 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to access outside valid memory")
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 690409ca8a186..cb2df8736ca85 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1406,7 +1406,13 @@ static int a6xx_set_supported_hw(struct device *dev, struct a6xx_gpu *a6xx_gpu,
 	int ret;
 
 	ret = nvmem_cell_read_u16(dev, "speed_bin", &speedbin);
-	if (ret) {
+	/*
+	 * -ENOENT means that the platform doesn't support speedbin which is
+	 * fine
+	 */
+	if (ret == -ENOENT) {
+		return 0;
+	} else if (ret) {
 		DRM_DEV_ERROR(dev,
 			      "failed to read speed-bin (%d). Some OPPs may not be supported by hardware",
 			      ret);
-- 
2.25.1

Re: [PATCH] drm/msm: Fix removal of valid error case when checking speed_bin

[Akhil P Oommen]

On 3/30/2021 7:04 AM, John Stultz wrote:
> Commit 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to
> access outside valid memory"), reworked the nvmem reading of
> "speed_bin", but in doing so dropped handling of the -ENOENT
> case which was previously documented as "fine".
> 
> That change resulted in the db845c board display to fail to
> start, with the following error:
> 
> adreno 5000000.gpu: [drm:a6xx_gpu_init] *ERROR* failed to read speed-bin (-2). Some OPPs may not be supported by hardware
> 
> Thus, this patch simply re-adds the ENOENT handling so the lack
> of the speed_bin entry isn't fatal for display, and gets things
> working on db845c.
> 
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: Sean Paul <sean@poorly.run>
> Cc: Jordan Crouse <jcrouse@codeaurora.org>
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Douglas Anderson <dianders@chromium.org>
> Cc: linux-arm-msm@vger.kernel.org
> Cc: freedreno@lists.freedesktop.org
> Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
> Cc: YongQin Liu <yongqin.liu@linaro.org>
> Reported-by: YongQin Liu <yongqin.liu@linaro.org>
> Fixes: 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to access outside valid memory")
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 690409ca8a186..cb2df8736ca85 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -1406,7 +1406,13 @@ static int a6xx_set_supported_hw(struct device *dev, struct a6xx_gpu *a6xx_gpu,
>   	int ret;
>   
>   	ret = nvmem_cell_read_u16(dev, "speed_bin", &speedbin);
> -	if (ret) {
> +	/*
> +	 * -ENOENT means that the platform doesn't support speedbin which is
> +	 * fine
> +	 */
> +	if (ret == -ENOENT) {
> +		return 0;
> +	} else if (ret) {
>   		DRM_DEV_ERROR(dev,
>   			      "failed to read speed-bin (%d). Some OPPs may not be supported by hardware",
>   			      ret);
> 

Reviewed-by: Akhil P Oommen <akhilpo@codeaurora.org>

This looks "fine" to me. ;)

-Akhil.

Re: [PATCH] drm/msm: Fix removal of valid error case when checking speed_bin

[Doug Anderson]

Hi,

On Mon, Mar 29, 2021 at 6:34 PM John Stultz <john.stultz@linaro.org> wrote:
>
> Commit 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to
> access outside valid memory"), reworked the nvmem reading of
> "speed_bin", but in doing so dropped handling of the -ENOENT
> case which was previously documented as "fine".
>
> That change resulted in the db845c board display to fail to
> start, with the following error:
>
> adreno 5000000.gpu: [drm:a6xx_gpu_init] *ERROR* failed to read speed-bin (-2). Some OPPs may not be supported by hardware
>
> Thus, this patch simply re-adds the ENOENT handling so the lack
> of the speed_bin entry isn't fatal for display, and gets things
> working on db845c.
>
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: Sean Paul <sean@poorly.run>
> Cc: Jordan Crouse <jcrouse@codeaurora.org>
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Douglas Anderson <dianders@chromium.org>
> Cc: linux-arm-msm@vger.kernel.org
> Cc: freedreno@lists.freedesktop.org
> Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
> Cc: YongQin Liu <yongqin.liu@linaro.org>
> Reported-by: YongQin Liu <yongqin.liu@linaro.org>
> Fixes: 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to access outside valid memory")
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Douglas Anderson <dianders@chromium.org>

Re: [PATCH] drm/msm: Fix removal of valid error case when checking speed_bin

[John Stultz]

On Mon, Mar 29, 2021 at 6:34 PM John Stultz <john.stultz@linaro.org> wrote:
>
> Commit 7bf168c8fe8c  ("drm/msm: Fix speed-bin support not to
> access outside valid memory"), reworked the nvmem reading of
> "speed_bin", but in doing so dropped handling of the -ENOENT
> case which was previously documented as "fine".
>
> That change resulted in the db845c board display to fail to
> start, with the following error:
>
> adreno 5000000.gpu: [drm:a6xx_gpu_init] *ERROR* failed to read speed-bin (-2). Some OPPs may not be supported by hardware
>
> Thus, this patch simply re-adds the ENOENT handling so the lack
> of the speed_bin entry isn't fatal for display, and gets things
> working on db845c.

Hey Folks,
  Just wanted to re-ping you on this, as it resolves a regression
introduced in 5.12-rc5 and I'm not yet seeing this in -next. Would be
nice to have this in place before 5.12 final.

thanks
-john