From: Chen-Yu Tsai wens@csie.org
[ Upstream commit bda8eaa6dee7525f4dac950810a85a88bf6c2ba0 ]
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-... [2] https://forum.armbian.com/topic/14282-headless-systems-and-sun4i_drm_hdmi-a1...
Fixes: 9c5681011a0c ("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@ke... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c index 9c3bdfd203373..63b4de81686ac 100644 --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c @@ -262,9 +262,8 @@ sun4i_hdmi_connector_detect(struct drm_connector *connector, bool force) struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector); unsigned long reg;
- if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_HPD_REG, reg, - reg & SUN4I_HDMI_HPD_HIGH, - 0, 500000)) { + reg = readl(hdmi->base + SUN4I_HDMI_HPD_REG); + if (reg & SUN4I_HDMI_HPD_HIGH) { cec_phys_addr_invalidate(hdmi->cec_adap); return connector_status_disconnected; }