linux-bl808/drivers/gpu/drm/sun4i
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
..
Kconfig
Makefile
sun4i_backend.c
sun4i_backend.h
sun4i_crtc.c
sun4i_crtc.h
sun4i_dotclock.c
sun4i_dotclock.h
sun4i_drv.c
sun4i_drv.h
sun4i_framebuffer.c
sun4i_framebuffer.h
sun4i_frontend.c
sun4i_frontend.h
sun4i_hdmi.h
sun4i_hdmi_ddc_clk.c
sun4i_hdmi_enc.c drm: sun4i: hdmi: Remove extra HPD polling 2020-06-30 10:01:48 +02:00
sun4i_hdmi_i2c.c
sun4i_hdmi_tmds_clk.c
sun4i_layer.c
sun4i_layer.h
sun4i_lvds.c
sun4i_lvds.h
sun4i_rgb.c
sun4i_rgb.h
sun4i_tcon.c
sun4i_tcon.h
sun4i_tv.c
sun6i_drc.c
sun6i_mipi_dsi.c
sun6i_mipi_dsi.h
sun8i_csc.c
sun8i_csc.h
sun8i_dw_hdmi.c
sun8i_dw_hdmi.h
sun8i_hdmi_phy.c
sun8i_hdmi_phy_clk.c
sun8i_mixer.c
sun8i_mixer.h
sun8i_tcon_top.c
sun8i_tcon_top.h
sun8i_ui_layer.c
sun8i_ui_layer.h
sun8i_ui_scaler.c
sun8i_ui_scaler.h
sun8i_vi_layer.c
sun8i_vi_layer.h
sun8i_vi_scaler.c
sun8i_vi_scaler.h
sunxi_engine.h