1. 23 Jul, 2021 8 commits
  2. 22 Jul, 2021 1 commit
  3. 21 Jul, 2021 11 commits
  4. 20 Jul, 2021 12 commits
  5. 19 Jul, 2021 5 commits
  6. 17 Jul, 2021 2 commits
  7. 15 Jul, 2021 1 commit
    • Douglas Anderson's avatar
      drm/dp: For drm_panel_dp_aux_backlight(), init backlight as disabled · 17a1837d
      Douglas Anderson authored
      Even after the DP AUX backlight on my board worked OK after applying
      the patch ("drm/panel-simple: Power the panel when probing DP AUX
      backlight") [1], I still noticed some strange timeouts being reported
      by ti_sn_aux_transfer(). Digging, I realized the problem was this:
      * Even though `enabled` in `struct dp_aux_backlight` was false, the
        base backlight structure (`base` in that structure) thought that the
        backlight was powered on.
      * If userspace wrote to sysfs in this state then we'd try to enable
        the backlight.
      * Unfortunatley, enabling the backlight didn't work because the panel
        itself wasn't powered.
      
      We can only use the backlight if the panel is on and the panel is not
      officially on when we probe (it's temporarily just on enough for us to
      talk to it).
      
      The important thing we want here is to get `BL_CORE_FBBLANK` set since
      userspace can't mess with that. This will keep us disabled until
      drm_panel enables us, which means that the panel is enabled
      first. Ideally we'd just set this in our `props` before calling
      devm_backlight_device_register() but the comments in the header file
      are pretty explicit that we're not supposed to much with the `state`
      ourselves. Because of this, there may be a small window where the
      backlight device is registered and someone could try to tweak with the
      backlight. This isn't likely to happen and even if it did, I don't
      believe this causes any huge problem.
      
      [1] https://lore.kernel.org/lkml/20210714093334.1.Idb41f87e5abae4aee0705db7458b0097fc50e7ab@changeid/Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
      Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/20210714101744.1.Ifc22696b27930749915e383f0108b7bcdc015a6e@changeid
      17a1837d