On Thu, Jun 13, 2019 at 07:04:03AM +0200, Sam Ravnborg wrote: > Hi Rodrigo. > > On Wed, Jun 12, 2019 at 11:10:54PM -0300, Rodrigo Siqueira wrote: > > For historical reason, the function drm_wait_vblank_ioctl always return > > -EINVAL if something gets wrong. This scenario limits the flexibility > > for the userspace make detailed verification of the problem and take > > some action. In particular, the validation of “if (!dev->irq_enabled)” > > in the drm_wait_vblank_ioctl is responsible for checking if the driver > > support vblank or not. If the driver does not support VBlank, the > > function drm_wait_vblank_ioctl returns EINVAL which does not represent > > the real issue; this patch changes this behavior by return EOPNOTSUPP. > > Additionally, some operations are unsupported by this function, and > > returns EINVAL; this patch also changes the return value to EOPNOTSUPP > > in this case. Lastly, the function drm_wait_vblank_ioctl is invoked by > > libdrm, which is used by many compositors; because of this, it is > > important to check if this change breaks any compositor. In this sense, > > the following projects were examined: > > > > * Drm-hwcomposer > > * Kwin > > * Sway > > * Wlroots > > * Wayland-core > > * Weston > > * Xorg (67 different drivers) > > > > For each repository the verification happened in three steps: > > > > * Update the main branch > > * Look for any occurrence "drmWaitVBlank" with the command: > > git grep -n "drmWaitVBlank" > > * Look in the git history of the project with the command: > > git log -SdrmWaitVBlank > > > > Finally, none of the above projects validate the use of EINVAL which > > make safe, at least for these projects, to change the return values. > > > > Change since V2: > > Daniel Vetter and Chris Wilson > > - Replace ENOTTY by EOPNOTSUPP > > - Return EINVAL if the parameters are wrong > > > > Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@xxxxxxxxx> > > --- > > Update: > > Now IGT has a way to validate if a driver has vblank support or not. > > See: https://gitlab.freedesktop.org/drm/igt-gpu-tools/commit/2d244aed69165753f3adbbd6468db073dc1acf9A > > > > drivers/gpu/drm/drm_vblank.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > > index 0d704bddb1a6..d76a783a7d4b 100644 > > --- a/drivers/gpu/drm/drm_vblank.c > > +++ b/drivers/gpu/drm/drm_vblank.c > > @@ -1578,10 +1578,10 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, > > unsigned int flags, pipe, high_pipe; > > > > if (!dev->irq_enabled) > > - return -EINVAL; > > + return -EOPNOTSUPP; > > > > if (vblwait->request.type & _DRM_VBLANK_SIGNAL) > > - return -EINVAL; > > + return -EOPNOTSUPP; > > > > if (vblwait->request.type & > > ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK | > > When touching this function, could I ask you to take a look at > eliminating the use of DRM_WAIT_ON()? > It comes from the deprecated drm_os_linux.h header, and it is only of > the few remaining users of DRM_WAIT_ON(). IIRC all previous attempts at removing that ended up with regressions. I think there are some dragons lurking inside that macro. -- Ville Syrjälä Intel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
