[PATCH] drm/radeon: Resume fbcon last

[Alex Deucher]

On Fri, May 30, 2014 at 10:37 AM, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> So a few people complained that
>
> commit 177cf92de4aa97ec1435987e91696ed8b5023130
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Tue Apr 1 22:14:59 2014 +0200
>
>     drm/crtc-helpers: fix dpms on logic
>
> which was merged into 3.15-rc1, broke resume on radeons. Strangely git
> bisect lead everyone to
>
> commit 25f397a429dfa43f22c278d0119a60a343aa568f
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Fri Jul 19 18:57:11 2013 +0200
>
>     drm/crtc-helper: explicit DPMS on after modeset
>
> which was merged long ago and actually part of 3.14.
>
> Digging deeper I've noticed (again) that with these changes the call
> to drm_helper_resume_force_mode in the radeon resume handlers was a
> no-op previously because everything gets shut down on suspend. radeon
> does this with explicit calls to drm_helper_connector_dpms with
> DPMS_OFF. But with 177c we now force the dpms state to ON, so suddenly
> resume_force_mode actually forced something.
>
> This was the intention of the change after all, the problem is that
> radeon resumes the fbdev console layer _before_ restoring the display,
> through calling fb_set_suspend. And fbcon does an immediate ->set_par,
> which in turn causes the same force mode restore to happen.
>
> Two concurrent modeset operations didn't lead to happiness. Fix this
> by delaying the fbcon resume until the end of the readeon resum
> functions.
>
> References: https://lkml.org/lkml/2014/5/29/1043
> References: https://lkml.org/lkml/2014/5/2/388
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=74751
> Tested-by: Ken Moffat <zarniwhoop at ntlworld.com>
> Cc: Alex Deucher <alexdeucher at gmail.com>
> Cc: Ken Moffat <zarniwhoop at ntlworld.com>
> Cc: Dave Airlie <airlied at redhat.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Thanks!

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/radeon/radeon_device.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
> index 9aa1afd1786e..8f434c6c4540 100644
> --- a/drivers/gpu/drm/radeon/radeon_device.c
> +++ b/drivers/gpu/drm/radeon/radeon_device.c
> @@ -1533,11 +1533,6 @@ int radeon_resume_kms(struct drm_device *dev, bool resume, bool fbcon)
>
>         radeon_restore_bios_scratch_regs(rdev);
>
> -       if (fbcon) {
> -               radeon_fbdev_set_suspend(rdev, 0);
> -               console_unlock();
> -       }
> -
>         /* init dig PHYs, disp eng pll */
>         if (rdev->is_atom_bios) {
>                 radeon_atom_encoder_init(rdev);
> @@ -1562,6 +1557,12 @@ int radeon_resume_kms(struct drm_device *dev, bool resume, bool fbcon)
>         }
>
>         drm_kms_helper_poll_enable(dev);
> +
> +       if (fbcon) {
> +               radeon_fbdev_set_suspend(rdev, 0);
> +               console_unlock();
> +       }
> +
>         return 0;
>  }
>
> --
> 1.9.2
>