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SubjectRe: [PATCH v5 80/80] ARM: dts: bcm2711: Enable the display pipeline
On Wed, Sep 30, 2020 at 04:07:58PM +0200, Maxime Ripard wrote:
> Hi Nathan,
>
> On Tue, Sep 29, 2020 at 03:15:26PM -0700, Nathan Chancellor wrote:
> > On Thu, Sep 03, 2020 at 10:01:52AM +0200, Maxime Ripard wrote:
> > > Now that all the drivers have been adjusted for it, let's bring in the
> > > necessary device tree changes.
> > >
> > > The VEC and PV3 are left out for now, since it will require a more specific
> > > clock setup.
> > >
> > > Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> > > Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
> > > Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
> > > Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
> > > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> >
> > Apologies if this has already been reported or have a solution but this
> > patch (and presumably series) breaks output to the serial console after
> > a certain point during init. On Raspbian, I see systemd startup messages
> > then the output just turns into complete garbage. It looks like this
> > patch is merged first in linux-next, which is why my bisect fell on the
> > DRM merge. I am happy to provide whatever information could be helpful
> > for debugging this. I am on the latest version of the firmware
> > (currently 26620cc9a63c6cb9965374d509479b4ee2c30241).
>
> Unfortunately, the miniUART is in the same clock tree than the core
> clock and will thus have those kind of issues when the core clock is
> changed (which is also something that one should expect when using the
> DRM or other drivers).
>
> The only real workaround there would be to switch to one of the PL011
> UARTs. I guess we can also somehow make the UART react to the core clock
> frequency changes, but that's going to require some effort
>
> Maxime

Ack, thank you for the reply! There does not really seem to be a whole
ton of documentation around using one of the other PL011 UARTs so for
now, I will just revert this commit locally.

Cheers,
Nathan

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