linux-kernel - Re: SPI not working on 5.10 and 5.11, bisected to 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors")

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Message-ID: <20210114115958.GB4854@sirena.org.uk>
Date:   Thu, 14 Jan 2021 11:59:58 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Sven Van Asbroeck <thesven73@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...abs.org" <linuxppc-dev@...abs.org>
Subject: Re: SPI not working on 5.10 and 5.11, bisected to 766c6b63aa04
 ("spi: fix client driver breakages when using GPIO descriptors")

On Thu, Jan 14, 2021 at 12:27:42PM +0100, Christophe Leroy wrote:

> Today I have in the DTS the CS GPIOs declared as ACTIVE_LOW.

> If I declare them as ACTIVE_HIGH instead, then I also have to set
> spi-cs-high property, otherwise of_gpio_flags_quirks() is not happy and
> forces the GPIO ACTIVE LOW.

> When I set spi-cs-high property, it sets the SPI_CS_HIGH bit in spi->mode.

OK, so it sounds like you want SPI_CS_HIGH and that is being set
correctly?

> In fsl_spi_chipselect(), we have
> 
> 	bool pol = spi->mode & SPI_CS_HIGH
> 
> Then
> 	pdata->cs_control(spi, pol);

> So changing the board config is compensated by the above, and at the end it still doesn't work.

This is a driver bug, the driver set_cs() operation should not be
modifying the value it is told to set.

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