Re: [PATCH v1] spi: fix client driver breakages when using GPIO descriptors

Andy Shevchenko
2020-11-09T14:24:24Z

On Fri, Nov 6, 2020 at 5:08 PM Sven Van Asbroeck <thesven73@gmail.com> wrote:
>
> From: Sven Van Asbroeck <thesven73@gmail.com>
>
> Commit f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
> introduced the optional use of GPIO descriptors for chip selects.
>
> A side-effect of this change: when a SPI bus uses GPIO descriptors,
> all its client devices have SPI_CS_HIGH set in spi->mode. This flag is
> required for the SPI bus to operate correctly.
>
> This unfortunately breaks many client drivers, which use the following
> pattern to configure their underlying SPI bus:
>
> static int client_device_probe(struct spi_device *spi)
> {
> ...
> spi->mode = SPI_MODE_0;
> spi->bits_per_word = 8;
> err = spi_setup(spi);
> ..
> }
>
> In short, many client drivers overwrite the SPI_CS_HIGH bit in
> spi->mode, and break the underlying SPI bus driver.

Sounds like "many SPI drivers have to be fixed".

--
With Best Regards,
Andy Shevchenko