The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From e32e5723256a99c5324824503572f743377dd0fe Mon Sep 17 00:00:00 2001 From: Maxime Ripard maxime@cerno.tech Date: Mon, 25 Oct 2021 17:28:55 +0200 Subject: [PATCH] drm/vc4: hdmi: Fix HPD GPIO detection
Prior to commit 6800234ceee0 ("drm/vc4: hdmi: Convert to gpiod"), in the detect hook, if we had an HPD GPIO we would only rely on it and return whatever state it was in.
However, that commit changed that by mistake to only consider the case where we have a GPIO and it returns a logical high, and would fall back to the other methods otherwise.
Since we can read the EDIDs when the HPD signal is low on some displays, we changed the detection status from disconnected to connected, and we would ignore an HPD pulse.
Fixes: 6800234ceee0 ("drm/vc4: hdmi: Convert to gpiod") Signed-off-by: Maxime Ripard maxime@cerno.tech Reviewed-by: Dave Stevenson dave.stevenson@raspberrypi.com Link: https://lore.kernel.org/r/20211025152903.1088803-3-maxime@cerno.tech
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 6469645a7ad5..07a67bf6d3a8 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -170,9 +170,9 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
- if (vc4_hdmi->hpd_gpio && - gpiod_get_value_cansleep(vc4_hdmi->hpd_gpio)) { - connected = true; + if (vc4_hdmi->hpd_gpio) { + if (gpiod_get_value_cansleep(vc4_hdmi->hpd_gpio)) + connected = true; } else if (HDMI_READ(HDMI_HOTPLUG) & VC4_HDMI_HOTPLUG_CONNECTED) { connected = true; }