linux/drivers/gpu
Chen-Yu Tsai bda8eaa6de
drm: sun4i: hdmi: Remove extra HPD polling
The HPD sense mechanism in Allwinner's old HDMI encoder hardware is more
or less an input-only GPIO. Other GPIO-based HPD implementations
directly return the current state, instead of polling for a specific
state and returning the other if that times out.

Remove the I/O polling from sun4i_hdmi_connector_detect() and directly
return a known state based on the current reading. This also gets rid
of excessive CPU usage by kworker as reported on Stack Exchange [1] and
Armbian forums [2].

 [1] https://superuser.com/questions/1515001/debian-10-buster-on-cubietruck-with-bug-in-sun4i-drm-hdmi
 [2] https://forum.armbian.com/topic/14282-headless-systems-and-sun4i_drm_hdmi-a10a20/

Fixes: 9c5681011a ("drm/sun4i: Add HDMI support")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200629060032.24134-1-wens@kernel.org
2020-06-30 10:01:48 +02:00
..
drm drm: sun4i: hdmi: Remove extra HPD polling 2020-06-30 10:01:48 +02:00
host1x gpu: host1x: Use SMMU on Tegra124 and Tegra210 2020-04-28 11:44:07 +02:00
ipu-v3
trace gpu/trace: add a gpu total memory usage tracepoint 2020-03-03 17:52:41 -05:00
vga
Makefile gpu/trace: add a gpu total memory usage tracepoint 2020-03-03 17:52:41 -05:00