netdev - Re: qca_spi: SPI_REG_SIGNATURE sometimes not recognized

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Date: Mon, 05 Feb 2024 01:36:00 +0100
From: Christoph Fritz <chf.fritz@...glemail.com>
To: Stefan Wahren <wahrenst@....net>
Cc: netdev <netdev@...r.kernel.org>
Subject: Re: qca_spi: SPI_REG_SIGNATURE sometimes not recognized

> >   working on a board with QCA7005, on probe() SPI_REG_SIGNATURE
> > sometimes fails (~1 out of 5 times) to be recognized correctly, even
> > after multiple reads and retries.

> at the time of writing the driver, i assumed the QCA7000 is always
> powered up (takes ~ 1 second) during probe of the driver and the driver
> could do the signature check during probe. But this doesn't work in all
> cases. So qca_spi driver has the module parameter qcaspi_pluggable,
> which is disabled per default. If you enable this, this will skip the
> signature check during probe and let the spi thread handle the
> synchronization.
> 
> Does this fix your problem?

Yes, thanks - this seems to fix the probe issue.

> Regardless of the results, i think qcaspi_pluggable should be enabled
> per default.

I think so too. Because the current default (off) is only appropriate
when the chip already gets powered up long before probing. This seems
unusual and at the same time understandable because the driver lacks
regulator and gpio-reset handling.

What about removing qcaspi_pluggable completely while adding a warning
when QCASPI_SYNC_UNKNOWN hits way too many times?

Thanks
  -- Christoph