From: Maxime Ripard maxime@cerno.tech
[ Upstream commit ae71ab585c819f83aec84f91eb01157a90552ef2 ]
This is a revert of commit fd5894fa2413 ("drm/vc4: hdmi: Remove clock rate initialization"), with the code slightly moved around.
It turns out that we can't downright remove that code from the driver, since the Pi0-3 and Pi4 are in different cases, and it only works for the Pi4.
Indeed, the commit mentioned above was relying on the RaspberryPi firmware clocks driver to initialize the rate if it wasn't done by the firmware. However, the Pi0-3 are using the clk-bcm2835 clock driver that wasn't doing this initialization. We therefore end up with the clock not being assigned a rate, and the CPU stalling when trying to access a register.
We can't move that initialization in the clk-bcm2835 driver, since the HSM clock we depend on is actually part of the HDMI power domain, so any rate setup is only valid when the power domain is enabled. Thus, we reinstated the minimum rate setup at runtime_suspend, which should address both issues.
Link: https://lore.kernel.org/dri-devel/20220922145448.w3xfywkn5ecak2et@pengutroni... Fixes: fd5894fa2413 ("drm/vc4: hdmi: Remove clock rate initialization") Reported-by: Marc Kleine-Budde mkl@pengutronix.de Reviewed-by: Javier Martinez Canillas javierm@redhat.com Tested-by: Stefan Wahren stefan.wahren@i2se.com Signed-off-by: Maxime Ripard maxime@cerno.tech Link: https://patchwork.freedesktop.org/patch/msgid/20220929-rpi-pi3-unplugged-fix... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/vc4/vc4_hdmi.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 1e5f68704d7d..780a19a75c3f 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -2871,6 +2871,15 @@ static int vc4_hdmi_runtime_resume(struct device *dev) u32 __maybe_unused value; int ret;
+ /* + * The HSM clock is in the HDMI power domain, so we need to set + * its frequency while the power domain is active so that it + * keeps its rate. + */ + ret = clk_set_min_rate(vc4_hdmi->hsm_clock, HSM_MIN_CLOCK_FREQ); + if (ret) + return ret; + ret = clk_prepare_enable(vc4_hdmi->hsm_clock); if (ret) return ret;