Re: [PATCH 0/4] pinctrl: pinctrl-zynqmp: Add tri-state configuration support

[Michal Simek]

Hi Laurent,

On 9/28/22 18:42, Laurent Pinchart wrote:
> On Wed, Sep 28, 2022 at 06:58:10PM +0300, Laurent Pinchart wrote:
> > Hi Sai,
> >
> > On Fri, Jun 17, 2022 at 04:16:55PM +0530, Sai Krishna Potthuri wrote:
> > > This series update the Xilinx firmware, ZynqMP dt-binding and ZynqMP
> > > pinctrl driver to handle 'output-enable' and 'bias-high-impedance'
> > > configurations. As part of these configurations, ZynqMP pinctrl driver
> > > takes care of pin tri-state setting.
> > > Also fix the kernel doc warning in ZynqMP pinctrl driver.
> >
> > I'm afraid this causes a regression :-( With this series applied, boot
> > breaks with the following message being printed to the serial console:
> >
> > Received exception
> > MSR: 0x200, EAR: 0xFF180198, EDR: 0x0, ESR: 0x64
> >
> > I've traced that to the probe of the UART, when it calls into the
> > firmware to set pin MIO18 to high impedance. According to v1.7 of the
> > ZynqMP registers reference (UG1087), there is no register at address
> > 0xFF180198.
> >
> > I am using the VCU TRD 2021.1 for testing. Does this series require a
> > firmware update ? If so backward compatibility needs to be preserved.
> > It's very late in the v6.0-rc cycle for a fix, a revert may be best at
> > this point, to give us time to fix the issue properly.
>
> I've now tested the VCU TRD 2022.1 (which AFAIK is the latest available
> version), and the problem doesn't occue then. It thus seems this depends
> on a firmware update, which is impractical at best for all old designs
> :-(

That's correct observation. Supporting these two properties requires newer pmufw 
or that message is received.
I will let Arun and Jyotheeswar to comment it. I don't think there is a way to 
detect which firmware has implementation for it available.

Thanks,
Michal