[PATCH v1 0/2] sprd drm cover letter

[PATCH v1 0/2] sprd drm cover letter

[Kevin Tang]

v1:
  remove the selected DRM_KMS_CMA_HELPER in kconfig
  drm-sprd-fix-potential-NULL-dereference

Kevin Tang (2):
  drm/sprd: remove the selected DRM_KMS_CMA_HELPER in kconfig
  drm/sprd: fix potential NULL dereference

 drivers/gpu/drm/sprd/Kconfig    | 1 -
 drivers/gpu/drm/sprd/sprd_dpu.c | 3 +++
 drivers/gpu/drm/sprd/sprd_drm.c | 8 ++------
 drivers/gpu/drm/sprd/sprd_dsi.c | 3 +++
 4 files changed, 8 insertions(+), 7 deletions(-)

-- 
2.29.0

[PATCH v1 1/2] drm/sprd: remove the selected DRM_KMS_CMA_HELPER in kconfig

[Kevin Tang]

On linux-next, commit 43531edd53f0 ("drm/sprd: add Unisoc's drm kms master") adds the config DRM_SPRD,
which selects DRM_KMS_CMA_HELPER.

However, commit 09717af7d13d ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option") just removed the
DRM_KMS_CMA_HELPER. So, the select DRM_KMS_CMA_HELPER refers to a non-existing kconfig symbol.

Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
---
 drivers/gpu/drm/sprd/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/sprd/Kconfig b/drivers/gpu/drm/sprd/Kconfig
index 3edeaeca0..9a9c7ebfc 100644
--- a/drivers/gpu/drm/sprd/Kconfig
+++ b/drivers/gpu/drm/sprd/Kconfig
@@ -3,7 +3,6 @@ config DRM_SPRD
 	depends on ARCH_SPRD || COMPILE_TEST
 	depends on DRM && OF
 	select DRM_GEM_CMA_HELPER
-	select DRM_KMS_CMA_HELPER
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select VIDEOMODE_HELPERS
-- 
2.29.0

Re: [PATCH v1 1/2] drm/sprd: remove the selected DRM_KMS_CMA_HELPER in kconfig

[Javier Martinez Canillas]

Hello Kevin,

On 12/24/21 15:12, Kevin Tang wrote:
> On linux-next, commit 43531edd53f0 ("drm/sprd: add Unisoc's drm kms master") adds the config DRM_SPRD,
> which selects DRM_KMS_CMA_HELPER.
> 

According to "The canonical patch format" section in [0], the body of the
explanation has to be line wrapped at 75 columns. But your sentences are
much longer than that.

[0]: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#the-canonical-patch-format

> However, commit 09717af7d13d ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option") just removed the
> DRM_KMS_CMA_HELPER. So, the select DRM_KMS_CMA_HELPER refers to a non-existing kconfig symbol.
> 
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
> ---

Other than that, the patch looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat

Re: [PATCH v1 1/2] drm/sprd: remove the selected DRM_KMS_CMA_HELPER in kconfig

[Thomas Zimmermann]

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Hi

Am 24.12.21 um 15:12 schrieb Kevin Tang:
> On linux-next, commit 43531edd53f0 ("drm/sprd: add Unisoc's drm kms master") adds the config DRM_SPRD,
> which selects DRM_KMS_CMA_HELPER.
> 
> However, commit 09717af7d13d ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option") just removed the
> DRM_KMS_CMA_HELPER. So, the select DRM_KMS_CMA_HELPER refers to a non-existing kconfig symbol.

With the long lines fixed, you can add

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

Selecting DRM_GEM_CMA_HELPER and DRM_KMS_HELPER at the same time acts 
like DRM_KMS_CMA_HELPER did before.

Best regards
Thomas

> 
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
> ---
>   drivers/gpu/drm/sprd/Kconfig | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sprd/Kconfig b/drivers/gpu/drm/sprd/Kconfig
> index 3edeaeca0..9a9c7ebfc 100644
> --- a/drivers/gpu/drm/sprd/Kconfig
> +++ b/drivers/gpu/drm/sprd/Kconfig
> @@ -3,7 +3,6 @@ config DRM_SPRD
>   	depends on ARCH_SPRD || COMPILE_TEST
>   	depends on DRM && OF
>   	select DRM_GEM_CMA_HELPER
> -	select DRM_KMS_CMA_HELPER
>   	select DRM_KMS_HELPER
>   	select DRM_MIPI_DSI
>   	select VIDEOMODE_HELPERS

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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Re: [PATCH v1 1/2] drm/sprd: remove the selected DRM_KMS_CMA_HELPER in kconfig

[Lukas Bulwahn]

On Fri, Dec 24, 2021 at 3:12 PM Kevin Tang <kevin3.tang@gmail.com> wrote:
>
> On linux-next, commit 43531edd53f0 ("drm/sprd: add Unisoc's drm kms master") adds the config DRM_SPRD,
> which selects DRM_KMS_CMA_HELPER.
>

That this commit is _currently_ on linux-next is just a matter of the
current state. The commit message that goes into the project's history
should probably not state "on linux-next";
this information is probably outdated or of no interest to any further
future reader at the time of reading.

So, just drop "On linux-next". The commit 43531edd53f0 ("drm/sprd: add
Unisoc's drm kms master") will exist until the end of time.

> However, commit 09717af7d13d ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option") just removed the
> DRM_KMS_CMA_HELPER. So, the select DRM_KMS_CMA_HELPER refers to a non-existing kconfig symbol.
>

I would be happy about acknowledging my work of reporting with a
Reported-by tag, although I accidently send the report only to you
without cc-ing the mailing lists.

Please add:
Reported-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>

That said you may also add a Reviewed-by tag now:
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>


Lukas

> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
> ---
>  drivers/gpu/drm/sprd/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/sprd/Kconfig b/drivers/gpu/drm/sprd/Kconfig
> index 3edeaeca0..9a9c7ebfc 100644
> --- a/drivers/gpu/drm/sprd/Kconfig
> +++ b/drivers/gpu/drm/sprd/Kconfig
> @@ -3,7 +3,6 @@ config DRM_SPRD
>         depends on ARCH_SPRD || COMPILE_TEST
>         depends on DRM && OF
>         select DRM_GEM_CMA_HELPER
> -       select DRM_KMS_CMA_HELPER
>         select DRM_KMS_HELPER
>         select DRM_MIPI_DSI
>         select VIDEOMODE_HELPERS
> --
> 2.29.0
>

[PATCH v1 2/2] drm/sprd: fix potential NULL dereference

[Kevin Tang]

platform_get_resource() may fail and return NULL, so check it's value
before using it.

'drm' could be null in sprd_drm_shutdown, and drm_warn maybe dereference
it, remove this warning log.

Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
---
 drivers/gpu/drm/sprd/sprd_dpu.c | 3 +++
 drivers/gpu/drm/sprd/sprd_drm.c | 8 ++------
 drivers/gpu/drm/sprd/sprd_dsi.c | 3 +++
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/sprd/sprd_dpu.c b/drivers/gpu/drm/sprd/sprd_dpu.c
index 06a3414ee..69683b7ba 100644
--- a/drivers/gpu/drm/sprd/sprd_dpu.c
+++ b/drivers/gpu/drm/sprd/sprd_dpu.c
@@ -790,6 +790,9 @@ static int sprd_dpu_context_init(struct sprd_dpu *dpu,
 	int ret;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
 	ctx->base = devm_ioremap(dev, res->start, resource_size(res));
 	if (!ctx->base) {
 		dev_err(dev, "failed to map dpu registers\n");
diff --git a/drivers/gpu/drm/sprd/sprd_drm.c b/drivers/gpu/drm/sprd/sprd_drm.c
index a077e2d4d..54030839e 100644
--- a/drivers/gpu/drm/sprd/sprd_drm.c
+++ b/drivers/gpu/drm/sprd/sprd_drm.c
@@ -154,12 +154,8 @@ static void sprd_drm_shutdown(struct platform_device *pdev)
 {
 	struct drm_device *drm = platform_get_drvdata(pdev);
 
-	if (!drm) {
-		drm_warn(drm, "drm device is not available, no shutdown\n");
-		return;
-	}
-
-	drm_atomic_helper_shutdown(drm);
+	if (drm)
+		drm_atomic_helper_shutdown(drm);
 }
 
 static const struct of_device_id drm_match_table[] = {
diff --git a/drivers/gpu/drm/sprd/sprd_dsi.c b/drivers/gpu/drm/sprd/sprd_dsi.c
index 911b3cddc..955c5995a 100644
--- a/drivers/gpu/drm/sprd/sprd_dsi.c
+++ b/drivers/gpu/drm/sprd/sprd_dsi.c
@@ -907,6 +907,9 @@ static int sprd_dsi_context_init(struct sprd_dsi *dsi,
 	struct resource *res;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
 	ctx->base = devm_ioremap(dev, res->start, resource_size(res));
 	if (!ctx->base) {
 		drm_err(dsi->drm, "failed to map dsi host registers\n");
-- 
2.29.0

Re: [PATCH v1 2/2] drm/sprd: fix potential NULL dereference

[Javier Martinez Canillas]

On 12/24/21 15:12, Kevin Tang wrote:
> platform_get_resource() may fail and return NULL, so check it's value
> before using it.
> 
> 'drm' could be null in sprd_drm_shutdown, and drm_warn maybe dereference
> it, remove this warning log.
>

I would split this second change in a separate patch and just keep this
one about checking the platform_get_resource() return value.

If you do that, feel free to add:

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat

Re: [PATCH v1 2/2] drm/sprd: fix potential NULL dereference

[Thomas Zimmermann]

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Hi,

on the changes for platform_get_resource(), you can

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

but see my comments below.

Am 24.12.21 um 15:12 schrieb Kevin Tang:
> platform_get_resource() may fail and return NULL, so check it's value
> before using it.
> 
> 'drm' could be null in sprd_drm_shutdown, and drm_warn maybe dereference
> it, remove this warning log.
> 
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
> ---
>   drivers/gpu/drm/sprd/sprd_dpu.c | 3 +++
>   drivers/gpu/drm/sprd/sprd_drm.c | 8 ++------
>   drivers/gpu/drm/sprd/sprd_dsi.c | 3 +++
>   3 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sprd/sprd_dpu.c b/drivers/gpu/drm/sprd/sprd_dpu.c
> index 06a3414ee..69683b7ba 100644
> --- a/drivers/gpu/drm/sprd/sprd_dpu.c
> +++ b/drivers/gpu/drm/sprd/sprd_dpu.c
> @@ -790,6 +790,9 @@ static int sprd_dpu_context_init(struct sprd_dpu *dpu,
>   	int ret;
>   
>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
> +

You can add an error message if this fails.


>   	ctx->base = devm_ioremap(dev, res->start, resource_size(res));
>   	if (!ctx->base) {
>   		dev_err(dev, "failed to map dpu registers\n");
> diff --git a/drivers/gpu/drm/sprd/sprd_drm.c b/drivers/gpu/drm/sprd/sprd_drm.c
> index a077e2d4d..54030839e 100644
> --- a/drivers/gpu/drm/sprd/sprd_drm.c
> +++ b/drivers/gpu/drm/sprd/sprd_drm.c
> @@ -154,12 +154,8 @@ static void sprd_drm_shutdown(struct platform_device *pdev)
>   {
>   	struct drm_device *drm = platform_get_drvdata(pdev);
>   
> -	if (!drm) {
> -		drm_warn(drm, "drm device is not available, no shutdown\n");
> -		return;
> -	}
> -
> -	drm_atomic_helper_shutdown(drm);
> +	if (drm)
> +		drm_atomic_helper_shutdown(drm);

This change should be in a separate patch. Instead of removing the 
warning, you should rather use dev_err() or dev_warn() from [1]. Not 
being able to shut down here looks like a serious driver bug that the 
user should know about.


>   }
>   
>   static const struct of_device_id drm_match_table[] = {
> diff --git a/drivers/gpu/drm/sprd/sprd_dsi.c b/drivers/gpu/drm/sprd/sprd_dsi.c
> index 911b3cddc..955c5995a 100644
> --- a/drivers/gpu/drm/sprd/sprd_dsi.c
> +++ b/drivers/gpu/drm/sprd/sprd_dsi.c
> @@ -907,6 +907,9 @@ static int sprd_dsi_context_init(struct sprd_dsi *dsi,
>   	struct resource *res;
>   
>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
> +

Again, an error message seems appropriate.

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/latest/source/include/linux/dev_printk.h#L145

>   	ctx->base = devm_ioremap(dev, res->start, resource_size(res));
>   	if (!ctx->base) {
>   		drm_err(dsi->drm, "failed to map dsi host registers\n");

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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