Skip to content

L
linux
Switch branch/tag
  1. 12 Jun, 2019 1 commit
  3. 11 Jun, 2019 8 commits
  5. 10 Jun, 2019 18 commits
  7. 09 Jun, 2019 1 commit
  9. 08 Jun, 2019 3 commits
  11. 07 Jun, 2019 7 commits
  13. 06 Jun, 2019 2 commits
    • Daniel Vetter's avatar
      drm/vkms: Forward timer right after drm_crtc_handle_vblank · 7355965d
      Daniel Vetter authored 
      In

commit def35e7c
Author: Shayenne Moura <shayenneluzmoura@gmail.com>
Date:   Wed Jan 30 14:06:36 2019 -0200

    drm/vkms: Bugfix extra vblank frame

we fixed the vblank counter to give accurate results outside of
drm_crtc_handle_vblank, which fixed bugs around vblank timestamps
being off-by-one and causing the vblank counter to jump when it
shouldn't.

The trouble is that this completely broke crc generation. Shayenne and
Rodrigo tracked this down to the vblank timestamp going backwards in
time somehow. Which then resulted in an underflow in drm_vblank.c
code, which resulted in all kinds of things breaking really badly.

The reason for this is that once we've called drm_crtc_handle_vblank
and the hrtimer isn't forwarded yet, we're returning a vblank
timestamp in the past. This race is really hard to hit since it's
small, except when you enable crc generation: In that case there's a
call to drm_crtc_accurate_vblank right in-betwen, so we're guaranteed
to hit the bug.

The fix is to roll the hrtimer forward _before_ we do the vblank
processing (which has a side-effect of incrementing the vblank
counter), and we always subtract one frame from the hrtimer - since
now it's always one frame in the future.

To make sure we don't hit this again also add a WARN_ON checking for
whether our timestamp is somehow moving into the past, which is never
should.

This also aligns more with how real hw works:
1. first all registers are updated with the new timestamp/vblank
counter values.
2. then an interrupt is generated
3. kernel interrupt handler eventually fires.

So doing this aligns vkms closer with what drm_vblank.c expects.
Document this also in a comment.

Cc: Shayenne Moura <shayenneluzmoura@gmail.com>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Tested-by: default avatarRodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Reviewed-by: default avatarRodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Signed-off-by: default avatarRodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190606084404.12014-1-daniel.vetter@ffwll.ch
      7355965d
    • Rodrigo Siqueira's avatar
      drm/vkms: Remove useless call to drm_connector_register/unregister() · 1ae752bf
      Rodrigo Siqueira authored 
      The function vkms_output_init() is invoked during the module
initialization, and it handles the creation/configuration of the vkms
essential elements (e.g., connectors, encoder, etc). Among the
initializations, this function tries to initialize a connector and
register it by calling drm_connector_register(). However, inside the
drm_connector_register(), at the beginning of this function there is the
following validation:

 if (!connector->dev->registered)
   return 0;

In this sense, invoke drm_connector_register() after initializing the
connector has no effect because the register field is false. The
connector register happens when drm_dev_register() is invoked; the same
issue exists with drm_connector_unregister(). Therefore, this commit
removes the unnecessary call to drm_connector_register() and
drm_connector_unregister().

Changes since v2:
* Remove unnecessary call to drm_connector_unregister()
* Remove unused label
Signed-off-by: default avatarRodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Reviewed-by: default avatarDaniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190315161142.23gfu32lueyqrmyq@smtp.gmail.com
      1ae752bf
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7