Raspberry Pi 3 Model B+ hangs in vc4_hdmi_runtime_resume()

[Marc Kleine-Budde]

On 27.09.2022 13:12:35, Stefan Wahren wrote:
> > > > yes the issue is only triggered without HDMI connected. I was able to
> > > > reproduce with an older vc4 firmware from 2020 (don't want to upgrade yet).
> > > > Kernel was also an arm64 build with defconfig.
> > > > 
> > > > Here some rough starting point for bisection:
> > > > 
> > > > 5.18.0 good
> > > > 5.19.0 bad
> > > > 5.19.6 bad
> > > Sorry it took a bit of time, it looks like I found another bug while
> > > trying to test this yesterday.
> > > 
> > > Your datapoints are interesting though. I have a custom configuration
> > > and it does boot 5.19 without an HDMI connected.
> > > 
> > > So I guess it leaves us with either the firmware version being different
> > > (I'm using a newer version, from March 2022), or the configuration. I'll
> > > test with defconfig.
> > So it turns out compiling vc4 as a module is the culprit.
> 
> Do you mean regardless of the kernel version in your case?

On Debian vc4 is a module, too, both on 5.18.x (good) and 5.19.6 (bad).

> In my test cases i build vc4 always as module.
> 
> > It's not clear to me why at this point, but the first register write in
> > vc4_hdmi_reset stalls.
>
> Sounds like timing issue or a missing dependency (clock or power domain)

Here it fails 100%, regardless if the module is automatically loaded by
udev or later on an idle system via insmod.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |
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