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From: Harry Wentland <harry.wentland@amd.com>
To: Anand K Mistry <amistry@google.com>, amd-gfx@lists.freedesktop.org
Cc: "Eryk Brol" <eryk.brol@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Qingqing Zhuo" <qingqing.zhuo@amd.com>,
	"Wayne Lin" <Wayne.Lin@amd.com>,
	"Rodrigo Siqueira" <Rodrigo.Siqueira@amd.com>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	"Leo Li" <sunpeng.li@amd.com>,
	"Aurabindo Pillai" <aurabindo.pillai@amd.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Bas Nieuwenhuizen" <bas@basnieuwenhuizen.nl>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Nikola Cornij" <nikola.cornij@amd.com>,
	"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH] drm/amd/display: Fix error code on failure to set brightness
Date: Tue, 8 Jun 2021 09:59:59 -0400	[thread overview]
Message-ID: <e599ffb5-da5c-e4bb-a7d6-c2208a48868d@amd.com> (raw)
In-Reply-To: <20210608143159.1.I230026301243fbcee23d408c75aa468c1fec58f7@changeid>

On 2021-06-08 12:32 a.m., Anand K Mistry wrote:
> The backlight_ops.update_status function is required to return a
> negative error code on failure. Returning a positive code may be
> interpreted as a success. This is true for the 'brightness' sysfs file,
> which passes through a non-zero value as the return value of the write()
> syscall. This is interpreted in user-space as a successful write of 1
> character, which is obviously wrong.
> 
> It's not clear exactly what error code to use, but EINVAL should be
> reasonable.
> 
> Signed-off-by: Anand K Mistry <amistry@google.com>

Thanks for your patch but this code has changed on amd-staging-drm-next.

Can you try with the latest? The new backlight_update_status will always
return 0 now.

Harry

> ---
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 652cc1a0e450..ad322613390d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3431,7 +3431,7 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
>  	else
>  		rc = dc_link_set_backlight_level(dm->backlight_link, brightness, 0);
>  
> -	return rc ? 0 : 1;
> +	return rc ? 0 : -EINVAL;
>  }
>  
>  static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
> 

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WARNING: multiple messages have this Message-ID (diff)
From: Harry Wentland <harry.wentland@amd.com>
To: Anand K Mistry <amistry@google.com>, amd-gfx@lists.freedesktop.org
Cc: "Eryk Brol" <eryk.brol@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Qingqing Zhuo" <qingqing.zhuo@amd.com>,
	"Wayne Lin" <Wayne.Lin@amd.com>,
	"Rodrigo Siqueira" <Rodrigo.Siqueira@amd.com>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	"Leo Li" <sunpeng.li@amd.com>,
	"Aurabindo Pillai" <aurabindo.pillai@amd.com>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Nikola Cornij" <nikola.cornij@amd.com>,
	"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH] drm/amd/display: Fix error code on failure to set brightness
Date: Tue, 8 Jun 2021 09:59:59 -0400	[thread overview]
Message-ID: <e599ffb5-da5c-e4bb-a7d6-c2208a48868d@amd.com> (raw)
In-Reply-To: <20210608143159.1.I230026301243fbcee23d408c75aa468c1fec58f7@changeid>

On 2021-06-08 12:32 a.m., Anand K Mistry wrote:
> The backlight_ops.update_status function is required to return a
> negative error code on failure. Returning a positive code may be
> interpreted as a success. This is true for the 'brightness' sysfs file,
> which passes through a non-zero value as the return value of the write()
> syscall. This is interpreted in user-space as a successful write of 1
> character, which is obviously wrong.
> 
> It's not clear exactly what error code to use, but EINVAL should be
> reasonable.
> 
> Signed-off-by: Anand K Mistry <amistry@google.com>

Thanks for your patch but this code has changed on amd-staging-drm-next.

Can you try with the latest? The new backlight_update_status will always
return 0 now.

Harry

> ---
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 652cc1a0e450..ad322613390d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3431,7 +3431,7 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
>  	else
>  		rc = dc_link_set_backlight_level(dm->backlight_link, brightness, 0);
>  
> -	return rc ? 0 : 1;
> +	return rc ? 0 : -EINVAL;
>  }
>  
>  static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
> 


WARNING: multiple messages have this Message-ID (diff)
From: Harry Wentland <harry.wentland@amd.com>
To: Anand K Mistry <amistry@google.com>, amd-gfx@lists.freedesktop.org
Cc: "Alex Deucher" <alexander.deucher@amd.com>,
	"Aurabindo Pillai" <aurabindo.pillai@amd.com>,
	"Bas Nieuwenhuizen" <bas@basnieuwenhuizen.nl>,
	"Christian König" <christian.koenig@amd.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"David Airlie" <airlied@linux.ie>,
	"Eryk Brol" <eryk.brol@amd.com>, "Leo Li" <sunpeng.li@amd.com>,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	"Nikola Cornij" <nikola.cornij@amd.com>,
	"Qingqing Zhuo" <qingqing.zhuo@amd.com>,
	"Rodrigo Siqueira" <Rodrigo.Siqueira@amd.com>,
	"Wayne Lin" <Wayne.Lin@amd.com>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/amd/display: Fix error code on failure to set brightness
Date: Tue, 8 Jun 2021 09:59:59 -0400	[thread overview]
Message-ID: <e599ffb5-da5c-e4bb-a7d6-c2208a48868d@amd.com> (raw)
In-Reply-To: <20210608143159.1.I230026301243fbcee23d408c75aa468c1fec58f7@changeid>

On 2021-06-08 12:32 a.m., Anand K Mistry wrote:
> The backlight_ops.update_status function is required to return a
> negative error code on failure. Returning a positive code may be
> interpreted as a success. This is true for the 'brightness' sysfs file,
> which passes through a non-zero value as the return value of the write()
> syscall. This is interpreted in user-space as a successful write of 1
> character, which is obviously wrong.
> 
> It's not clear exactly what error code to use, but EINVAL should be
> reasonable.
> 
> Signed-off-by: Anand K Mistry <amistry@google.com>

Thanks for your patch but this code has changed on amd-staging-drm-next.

Can you try with the latest? The new backlight_update_status will always
return 0 now.

Harry

> ---
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 652cc1a0e450..ad322613390d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3431,7 +3431,7 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
>  	else
>  		rc = dc_link_set_backlight_level(dm->backlight_link, brightness, 0);
>  
> -	return rc ? 0 : 1;
> +	return rc ? 0 : -EINVAL;
>  }
>  
>  static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
> 


  reply	other threads:[~2021-06-08 14:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08  4:32 [PATCH] drm/amd/display: Fix error code on failure to set brightness Anand K Mistry
2021-06-08  4:32 ` Anand K Mistry
2021-06-08  4:32 ` Anand K Mistry
2021-06-08 13:59 ` Harry Wentland [this message]
2021-06-08 13:59   ` Harry Wentland
2021-06-08 13:59   ` Harry Wentland
2021-06-09  0:55   ` Anand K. Mistry
2021-06-09  0:55     ` Anand K. Mistry
2021-06-09  0:55     ` Anand K. Mistry

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