Messages in this thread | | | Date | Fri, 11 Nov 2022 22:08:39 +0100 | Subject | Re: [PATCH 1/2] drm/vc4: hdmi: Enforce the minimum rate at runtime_resume | From | Stefan Wahren <> |
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Hi Maxime,
Am 29.09.22 um 11:21 schrieb Maxime Ripard: > 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@pengutronix.de/ > Fixes: fd5894fa2413 ("drm/vc4: hdmi: Remove clock rate initialization") > Reported-by: Marc Kleine-Budde <mkl@pengutronix.de> > Signed-off-by: Maxime Ripard <maxime@cerno.tech> > --- > 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 199bc398817f..2e28fe16ed5e 100644 > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c > @@ -2891,6 +2891,15 @@ 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; > +
unfortunately this breaks X on Raspberry Pi 4 in Linux 6.0.5 (multi_v7_defconfig + LPAE). Today i saw this report [1] and bisected the issue down to this patch. Shame on me that i only tested this patch with Rpi 3B+ :-(
Best regards
[1] - https://bugzilla.suse.com/show_bug.cgi?id=1205259
> ret = clk_prepare_enable(vc4_hdmi->hsm_clock); > if (ret) > return ret; >
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