On 10/02/2014 08:52 PM, Andrzej Hajda wrote: > Hi, > > +CC possible victims > > On 10/02/2014 12:52 PM, Inki Dae wrote: >> On 2014? 10? 02? 17:58, Joonyoung Shim wrote: >>> Hi Andrzej, >>> >>> On 10/01/2014 05:14 PM, Andrzej Hajda wrote: >>>> The patch disables vblanks during dpms off only if pagefilp has >>>> not been finished. It also replaces drm_vblank_off with >>>> drm_crtc_vblank_put. >>>> It fixes issue with page_flip ioctl not being able to acquire vblank >>>> counter. >>> This problem isn't related with pageflip, it just causes from >>> 7ffd7a68511c710b84db3548a1997fd2625f580a commit (drm: Always reject >>> drm_vblank_get() after drm_vblank_off()). >>> >>> We need to use drm_vblank_on() as a counterpart to drm_vblank_off() >>> after the commit . > > This patch should break also other drivers, it seems at least following > drms could be affected: > armada, sti, tegra.
Indeed we (tegra) have just been hit by this. The problem seems to come from the fact that we have been using drm_vblank_pre_modeset, drm_vblank_post_modeset and drm_vblank_off conjointly. All these functions depend on the value of vblank->inmodeset, and 7ffd7a68511 increases the vblank reference counter only in drm_vblank_off, which can result in the acquired reference never being released. The following seems to fix this for Tegra, by stopping using drm_vblank_pre/post_modeset and relying on drm_vblank_off/on instead: diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c index b08df07cad47..3955d81236d0 100644 --- a/drivers/gpu/drm/tegra/dc.c +++ b/drivers/gpu/drm/tegra/dc.c @@ -739,7 +739,6 @@ static const struct drm_crtc_funcs tegra_crtc_funcs = { static void tegra_crtc_disable(struct drm_crtc *crtc) { - struct tegra_dc *dc = to_tegra_dc(crtc); struct drm_device *drm = crtc->dev; struct drm_plane *plane; @@ -755,7 +754,7 @@ static void tegra_crtc_disable(struct drm_crtc *crtc) } } - drm_vblank_off(drm, dc->pipe); + drm_crtc_vblank_off(crtc); } static bool tegra_crtc_mode_fixup(struct drm_crtc *crtc, @@ -844,7 +843,7 @@ static int tegra_crtc_mode_set(struct drm_crtc *crtc, u32 value; int err; - drm_vblank_pre_modeset(crtc->dev, dc->pipe); + drm_crtc_vblank_off(crtc); err = tegra_crtc_setup_clk(crtc, mode); if (err) { @@ -946,7 +945,7 @@ static void tegra_crtc_commit(struct drm_crtc *crtc) value = GENERAL_ACT_REQ | WIN_A_ACT_REQ; tegra_dc_writel(dc, value, DC_CMD_STATE_CONTROL); - drm_vblank_post_modeset(crtc->dev, dc->pipe); + drm_crtc_vblank_on(crtc); } static void tegra_crtc_load_lut(struct drm_crtc *crtc) Thierry, does this look ok to you? But there might be another issue, which is that calls to drm_vblank_get() will return -EINVAL if invoked between drm_blank_off and drm_blank_on. Is this really the desired behavior? Can it at least happen? If so, how are drivers supposed to react to this situation?