Re: [PATCH 1/3] drm/nouveau: Use drm_vblank_on/off consistently

Mario Kleiner
2015-05-29T16:50:06Z

On 05/27/2015 11:04 AM, Daniel Vetter wrote:
> In
>
> commit 9cba5efab5a8145ae6c52ea273553f069c294482
> Author: Mario Kleiner <mario.kleiner.de@gmail.com>
> Date: Tue Jul 29 02:36:44 2014 +0200
>
> drm/nouveau: Dis/Enable vblank irqs during suspend/resume
>
> drm_vblank_on/off calls where added around suspend/resume to make sure
> vblank stay doesn't go boom over that transition. But nouveau already
> used drm_vblank_pre/post_modeset over modesets. Instead use
> drm_vblank_on/off everyhwere. The slight change here is that after
> _off drm_vblank_get will refuse to work right away, but nouveau
> doesn't seem to depend upon that anywhere outside of the pageflip
> paths.
>
> The longer-term plan here is to switch all kms drivers to
> drm_vblank_on/off so that common code like pending event cleanup can
> be done there, while drm_vblank_pre/post_modeset will be purely
> drm internal for the old UMS ioctl.
>
> Note that the drm_vblank_off still seems required in the suspend path
> since nouveau doesn't explicitly disable crtcs. But on the resume side
> drm_helper_resume_force_mode should end up calling drm_vblank_on
> through the nouveau crtc hooks already. Hence remove the call in the
> resume code.
>
> Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
> Cc: Ben Skeggs <bskeggs@redhat.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
> drivers/gpu/drm/nouveau/dispnv04/crtc.c | 4 ++--
> drivers/gpu/drm/nouveau/nouveau_display.c | 4 ----
> 2 files changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/dispnv04/crtc.c b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
> index 3d96b49fe662..dab24066fa21 100644
> --- a/drivers/gpu/drm/nouveau/dispnv04/crtc.c
> +++ b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
> @@ -708,7 +708,7 @@ static void nv_crtc_prepare(struct drm_crtc *crtc)
> if (nv_two_heads(dev))
> NVSetOwner(dev, nv_crtc->index);
>
> - drm_vblank_pre_modeset(dev, nv_crtc->index);
> + drm_vblank_off(dev, nv_crtc->index);
> funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
>
> NVBlankScreen(dev, nv_crtc->index, true);
> @@ -740,7 +740,7 @@ static void nv_crtc_commit(struct drm_crtc *crtc)
> #endif
>
> funcs->dpms(crtc, DRM_MODE_DPMS_ON);
> - drm_vblank_post_modeset(dev, nv_crtc->index);
> + drm_vblank_on(dev, nv_crtc->index);
> }

The above hunk is probably correct, but i couldn't test it without
sufficiently old pre-nv 50 hardware.

>
> static void nv_crtc_destroy(struct drm_crtc *crtc)
> diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
> index 8670d90cdc11..d824023f9fc6 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_display.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_display.c
> @@ -620,10 +620,6 @@ nouveau_display_resume(struct drm_device *dev, bool runtime)
> nv_crtc->lut.depth = 0;
> }
>
> - /* Make sure that drm and hw vblank irqs get resumed if needed. */
> - for (head = 0; head < dev->mode_config.num_crtc; head++)
> - drm_vblank_on(dev, head);
> -
> /* This should ensure we don't hit a locking problem when someone
> * wakes us up via a connector. We should never go into suspend
> * while the display is on anyways.
>

Tested this one and this hunk breaks suspend/resume. After a
suspend/resume cycle, all OpenGL apps and composited desktop are dead,
as the core can't get any vblank irq's enabled anymore.

So the drm_vblank_on() is still needed here.

thanks,
-mario