[PATCH] drm/fb_helper: Disable all crtc's when initial setup fails.

[PATCH] drm/fb_helper: Disable all crtc's when initial setup fails.

[Maarten Lankhorst]

Some drivers like i915 start with crtc's enabled, but with deferred
fbcon setup they were no longer disabled as part of fbdev setup.
Headless units could no longer enter pc3 state because the crtc was
still enabled.

Fix this by calling restore_fbdev_mode when we would have called
it otherwise once during initial fbdev setup.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: ca91a2758fce ("drm/fb-helper: Support deferred setup")
Cc: <stable@vger.kernel.org> # v4.14+
Reported-by: Thomas Voegtle <tv@lio96.de>
---
 drivers/gpu/drm/drm_fb_helper.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 07374008f146..e56166334455 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1809,6 +1809,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 
 	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
 		DRM_INFO("Cannot find any crtc or sizes\n");
+
+		/* First time: disable all crtc's.. */
+		if (!fb_helper->deferred_setup && !READ_ONCE(fb_helper->dev->master))
+			restore_fbdev_mode(fb_helper);
 		return -EAGAIN;
 	}
 
-- 
2.15.0

Re: [PATCH] drm/fb_helper: Disable all crtc's when initial setup fails.

[Daniel Vetter]

On Tue, Nov 28, 2017 at 12:16:03PM +0100, Maarten Lankhorst wrote:
> Some drivers like i915 start with crtc's enabled, but with deferred
> fbcon setup they were no longer disabled as part of fbdev setup.
> Headless units could no longer enter pc3 state because the crtc was
> still enabled.
> 
> Fix this by calling restore_fbdev_mode when we would have called
> it otherwise once during initial fbdev setup.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Fixes: ca91a2758fce ("drm/fb-helper: Support deferred setup")

Please use dim fixes to get a more complete Cc: list for regression fixes.

> Cc: <stable@vger.kernel.org> # v4.14+
> Reported-by: Thomas Voegtle <tv@lio96.de>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

But please confirm with the reporter that it indeed fixes the issue before
pushing.
-Daniel

> ---
>  drivers/gpu/drm/drm_fb_helper.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 07374008f146..e56166334455 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1809,6 +1809,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
>  
>  	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
>  		DRM_INFO("Cannot find any crtc or sizes\n");
> +
> +		/* First time: disable all crtc's.. */
> +		if (!fb_helper->deferred_setup && !READ_ONCE(fb_helper->dev->master))
> +			restore_fbdev_mode(fb_helper);
>  		return -EAGAIN;
>  	}
>  
> -- 
> 2.15.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH] drm/fb_helper: Disable all crtc's when initial setup fails.

[Thomas Voegtle]

On Tue, 28 Nov 2017, Daniel Vetter wrote:

> On Tue, Nov 28, 2017 at 12:16:03PM +0100, Maarten Lankhorst wrote:
>> Some drivers like i915 start with crtc's enabled, but with deferred
>> fbcon setup they were no longer disabled as part of fbdev setup.
>> Headless units could no longer enter pc3 state because the crtc was
>> still enabled.
>>
>> Fix this by calling restore_fbdev_mode when we would have called
>> it otherwise once during initial fbdev setup.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Fixes: ca91a2758fce ("drm/fb-helper: Support deferred setup")
>
> Please use dim fixes to get a more complete Cc: list for regression fixes.
>
>> Cc: <stable@vger.kernel.org> # v4.14+
>> Reported-by: Thomas Voegtle <tv@lio96.de>
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>
> But please confirm with the reporter that it indeed fixes the issue before
> pushing.
> -Daniel

I re-checked the latest version of the patch and it indeed fixes the 
problem.

Thanks,

    Thomas

Re: [PATCH] drm/fb_helper: Disable all crtc's when initial setup fails.

[Maarten Lankhorst]

Op 28-11-17 om 16:13 schreef Thomas Voegtle:
> On Tue, 28 Nov 2017, Daniel Vetter wrote:
>
>> On Tue, Nov 28, 2017 at 12:16:03PM +0100, Maarten Lankhorst wrote:
>>> Some drivers like i915 start with crtc's enabled, but with deferred
>>> fbcon setup they were no longer disabled as part of fbdev setup.
>>> Headless units could no longer enter pc3 state because the crtc was
>>> still enabled.
>>>
>>> Fix this by calling restore_fbdev_mode when we would have called
>>> it otherwise once during initial fbdev setup.
>>>
>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>>> Fixes: ca91a2758fce ("drm/fb-helper: Support deferred setup")
>>
>> Please use dim fixes to get a more complete Cc: list for regression fixes.
>>
>>> Cc: <stable@vger.kernel.org> # v4.14+
>>> Reported-by: Thomas Voegtle <tv@lio96.de>
>>
>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>
>> But please confirm with the reporter that it indeed fixes the issue before
>> pushing.
>> -Daniel
>
> I re-checked the latest version of the patch and it indeed fixes the problem.
>
> Thanks,
>
>    Thomas
>
Pushed, thanks for the report. :)

~Maarten