1. Mar 13, 2024
  2. Mar 07, 2024
  3. Mar 04, 2024
  4. Mar 01, 2024
  5. Feb 29, 2024
    • Douglas Anderson's avatar
      drm/dp: Don't attempt AUX transfers when eDP panels are not powered · 8df1ddb5
      Douglas Anderson authored
      
      
      If an eDP panel is not powered on then any attempts to talk to it over
      the DP AUX channel will timeout. Unfortunately these attempts may be
      quite slow. Userspace can initiate these attempts either via a
      /dev/drm_dp_auxN device or via the created i2c device.
      
      Making the DP AUX drivers timeout faster is a difficult proposition.
      In theory we could just poll the panel's HPD line in the AUX transfer
      function and immediately return an error there. However, this is
      easier said than done. For one thing, there's no hard requirement to
      hook the HPD line up for eDP panels and it's OK to just delay a fixed
      amount. For another thing, the HPD line may not be fast to probe. On
      parade-ps8640 we need to wait for the bridge chip's firmware to boot
      before we can get the HPD line and this is a slow process.
      
      The fact that the transfers are taking so long to timeout is causing
      real problems. The open source fwupd daemon sometimes scans DP busses
      looking for devices whose firmware need updating. If it happens to
      scan while a panel is turned off this scan can take a long time. The
      fwupd daemon could try to be smarter and only scan when eDP panels are
      turned on, but we can also improve the behavior in the kernel.
      
      Let's let eDP panels drivers specify that a panel is turned off and
      then modify the common AUX transfer code not to attempt a transfer in
      this case.
      
      Tested-by: default avatarSteev Klimaszewski <steev@kali.org>
      Reviewed-by: default avatarHsin-Yi Wang <hsinyi@chromium.org>
      Tested-by: default avatarEizan Miyamoto <eizan@chromium.org>
      Acked-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
      Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
      Link: https://patchwork.freedesktop.org/patch/msgid/20240202141109.1.I24277520ac754ea538c9b14578edc94e1df11b48@changeid
      8df1ddb5
  6. Feb 28, 2024