| Message ID | 20190520001208.yh4jivl5lcc7iarh@smtp.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/vkms: Avoid extra discount in the timestamp value | expand |
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 7508815fac11..3ce60e66673e 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -74,9 +74,13 @@ bool vkms_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe, { struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev); struct vkms_output *output = &vkmsdev->output; + struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; *vblank_time = output->vblank_hrtimer.node.expires; + if (*vblank_time == vblank->time) + return true; + if (!in_vblank_irq) *vblank_time -= output->period_ns;
After the commit def35e7c5926 ("drm/vkms: Bugfix extra vblank frame") some of the crc tests (IGT) start to fail in the vkms with the following error: [drm:drm_crtc_add_crc_entry [drm]] *ERROR* Overflow of CRC buffer, userspace reads too slow. [drm] failed to queue vkms_crc_work_handle ... The commit def35e7c5926 ("drm/vkms: Bugfix extra vblank frame") added an operation for decrement the timestamp value returned by `get_vblank_timestamp()` which solved the problems related to kms_flip tests. However, each call to `get_vblank_timestamp()` reduces the timestamp even when it is not required. Such decrement generates a negative number in the following calculation within `drm_update_vblank_count()`: u64 diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time)); Next, the DIV_ROUND_CLOSEST_ULL macro is invoked using the diff_ns value, which generates an undefined result. Therefore, the returned frame is incorrect, which assign a huge number to the variable frame_end. In this case, causing the loop (`vkms_crc_work_handle()`) below to take a long time: frame_end = drm_crtc_accurate_vblank_count(crtc); while (frame_start <= frame_end) drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); This commit fixes this issue by adding a check that validates whether the current vblank timestamp is still the same, thus avoiding excessive timestamp decrement of the timestamp value. Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Signed-off-by: Shayenne Moura <shayenneluzmoura@gmail.com> --- drivers/gpu/drm/vkms/vkms_crtc.c | 4 ++++ 1 file changed, 4 insertions(+)