From: Rodrigo Siqueira <rodrigosiqueiramelo@xxxxxxxxx> [ Upstream commit aed6105b28b10613f16c0bfe97525fe5a23338df ] For historical reasons, the function drm_wait_vblank_ioctl always return -EINVAL if something gets wrong. This scenario limits the flexibility for the userspace to make detailed verification of any 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, drm_crtc_get_sequence_ioctl and drm_crtc_queue_sequence_ioctl, also returns EINVAL if vblank is not supported; this patch also changes the return value to EOPNOTSUPP in these functions. Lastly, these functions are 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 * Weston * Mutter * Xorg (67 different drivers) For each repository the verification happened in three steps: * Update the main branch * Look for any occurrence of "drmCrtcQueueSequence", "drmCrtcGetSequence", and "drmWaitVBlank" with the command git grep -n "STRING". * Look in the git history of the project with the command git log -S<STRING> None of the above projects validate the use of EINVAL when using drmWaitVBlank(), which make safe, at least for these projects, to change the return values. On the other hand, mesa and xserver project uses drmCrtcQueueSequence() and drmCrtcGetSequence(); this change is harmless for both projects. Change since V5 (Pekka Paalanen): - Check if the change also affects Mutter Change since V4 (Daniel): - Also return EOPNOTSUPP in drm_crtc_[get|queue]_sequence_ioctl Change since V3: - Return EINVAL for _DRM_VBLANK_SIGNAL (Daniel) Change since V2: Daniel Vetter and Chris Wilson - Replace ENOTTY by EOPNOTSUPP - Return EINVAL if the parameters are wrong Cc: Keith Packard <keithp@xxxxxxxxxx> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Cc: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx> Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@xxxxxxxxx> Reviewed-by: Daniel Vetter <daniel@xxxxxxxx> Acked-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20191002140516.adeyj3htylimmlmg@xxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/drm_vblank.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index fd1fbc77871f1..552ec82e9bc52 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1581,7 +1581,7 @@ 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; @@ -1838,7 +1838,7 @@ int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data, return -EOPNOTSUPP; if (!dev->irq_enabled) - return -EINVAL; + return -EOPNOTSUPP; crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id); if (!crtc) @@ -1896,7 +1896,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, return -EOPNOTSUPP; if (!dev->irq_enabled) - return -EINVAL; + return -EOPNOTSUPP; crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id); if (!crtc) -- 2.20.1
