Hi,

Am 30.09.20 um 18:38 schrieb Nathan Chancellor:

On Wed, Sep 30, 2020 at 04:07:58PM +0200, Maxime Ripard wrote:

quoted

Hi Nathan,

On Tue, Sep 29, 2020 at 03:15:26PM -0700, Nathan Chancellor wrote:

quoted

On Thu, Sep 03, 2020 at 10:01:52AM +0200, Maxime Ripard wrote:

quoted

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 <redacted>
Tested-by: Stefan Wahren <redacted>
Signed-off-by: Maxime Ripard <redacted>

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.

there was a patch series & discussion about this topic, but we finally
didn't find a rock solid solution.

You can have a look at "[RFC 5/5] serial: 8250: bcm2835aux: add notifier
to follow clock changes" from 3.4.2019 on linux-rpi-kernel.

Best regards

Cheers,
Nathan

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