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

Daniel Vetter
2015-05-29T17:35:22Z

On Fri, May 29, 2015 at 07:23:35PM +0200, Mario Kleiner wrote:
>
>
> On 05/29/2015 07:19 PM, Daniel Vetter wrote:
> >On Fri, May 29, 2015 at 06:50:06PM +0200, Mario Kleiner wrote:
> >>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.
> >
> >Hm that's very surprising. As mentioned above the force_mode_restore
> >should be calling nv_crtc_prepare already and fix this all up for us. I
> >guess I need to dig out my nv card and trace what's really going on here.
> >
> >Enabling interrupts when the crtc is off isn't a good idea.
> >-Daniel
> >
>
> I think the nv_crtc_prepare() path modified in your first hunk is only for
> the original nv04 display engine for very old cards. nv50+ (GeForce-8 and
> later) take different paths.

Oh right totally missed the nv50+ code. I only grepped for
pre/post_modeset ...

Below untested diff should help. I also realized that the pre-nv50 code
lacks drm_vblank_on/off in the dpms callback, so there's more work to do
anyway for this one here.

Thanks, Daniel

diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index 7da7958556a3..a16c37d8f7e1 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -997,6 +997,10 @@ nv50_crtc_cursor_show_hide(struct nouveau_crtc *nv_crtc, bool show, bool update)
static void
nv50_crtc_dpms(struct drm_crtc *crtc, int mode)
{
+ if (mode == DRM_MODE_DPMS_ON)
+ drm_crtc_vblank_on(crtc);
+ else
+ drm_crtc_vblank_off(crtc);
}

static void
@@ -1036,6 +1040,8 @@ nv50_crtc_prepare(struct drm_crtc *crtc)
}

nv50_crtc_cursor_show_hide(nv_crtc, false, false);
+
+ drm_crtc_vblank_on(crtc);
}

static void
@@ -1045,6 +1051,8 @@ nv50_crtc_commit(struct drm_crtc *crtc)
struct nv50_mast *mast = nv50_mast(crtc->dev);
u32 *push;

+ drm_crtc_vblank_on(crtc);
+
push = evo_wait(mast, 32);
if (push) {
if (nv50_vers(mast) < G82_DISP_CORE_CHANNEL_DMA) {
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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