From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Sven Van Asbroeck <thesven73@gmail.com>
Cc: Mark Brown <broonie@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
Simon Han <z.han@kunbus.com>, Lukas Wunner <lukas@wunner.de>,
linux-spi <linux-spi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] spi: fix client driver breakages when using GPIO descriptors
Date: Mon, 9 Nov 2020 16:25:10 +0200 [thread overview]
Message-ID: <CAHp75VfP1R7bXV6nWWnovWB5BMFcNNEmwBQXheBCUVDbr=xXGA@mail.gmail.com> (raw)
In-Reply-To: <20201106150706.29089-1-TheSven73@gmail.com>
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
next prev parent reply other threads:[~2020-11-09 14:24 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 15:07 [PATCH v1] spi: fix client driver breakages when using GPIO descriptors Sven Van Asbroeck
2020-11-09 14:25 ` Andy Shevchenko [this message]
2020-11-09 14:41 ` Sven Van Asbroeck
2020-11-11 1:05 ` Linus Walleij
2020-11-11 12:33 ` Mark Brown
2020-11-11 13:36 ` Linus Walleij
2020-11-16 21:06 ` Mark Brown
2020-11-18 1:03 ` Linus Walleij
2020-11-18 11:40 ` Mark Brown
2020-11-24 15:21 ` Linus Walleij
2020-11-24 16:40 ` Mark Brown
2020-11-25 9:19 ` Grant Likely
2020-11-25 9:17 ` Grant Likely
2020-11-11 1:08 ` Linus Walleij
2020-11-11 15:48 ` Mark Brown
2020-11-11 16:24 ` Sven Van Asbroeck
2020-11-11 16:32 ` Mark Brown
2020-11-12 11:41 ` Charles Keepax
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