From: Andreas Kemnade <andreas@kemnade.info>
To: Sven Van Asbroeck <thesven73@gmail.com>
Cc: "H. Nikolaus Schaller" <hns@goldelico.com>,
Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
linux-spi <linux-spi@vger.kernel.org>,
linux-gpio@vger.kernel.org,
devicetree <devicetree@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Discussions about the Letux Kernel
<letux-kernel@openphoenux.org>,
kernel@pyra-handheld.com,
Maxime Ripard <maxime.ripard@bootlin.com>,
Lukas Wunner <lukas@wunner.de>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Maxime Ripard <maxime@cerno.tech>
Subject: Re: [PATCH] spi: dt-bindings: clarify CS behavior for spi-cs-high and gpio descriptors
Date: Wed, 9 Dec 2020 21:01:33 +0100 [thread overview]
Message-ID: <20201209210133.44ab9c97@aktux> (raw)
In-Reply-To: <CAGngYiVL9M72hFRWnmT_8RRX9pUTSLsNuYz6mUo0Be4Vivk7Xw@mail.gmail.com>
On Wed, 9 Dec 2020 14:04:26 -0500
Sven Van Asbroeck <thesven73@gmail.com> wrote:
> On Wed, Dec 9, 2020 at 1:16 PM H. Nikolaus Schaller <hns@goldelico.com> wrote:
> >
> > This is also what made me wonder if that is really intended because then
> > the whole discussion about the cs-gpio-flags and inversion and the fixes
> > would not have been needed. The current code and fixes are all about
> > not ignoring the flags...
>
> The inversion you witnessed was a bug caused by spi client drivers that
> simply "plow over" the SPI_CS_HIGH mode flag. This includes the panel driver
> you're using, see:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c?h=v5.10-rc6#n337
>
ah, it would be set in spi->mode and is cleared by
spi->mode = SPI_MODE_3;
Hmm, but we have
spi-cpol;
spi-cpha;
in devicetree. Why do we need that spi->mode line at all?
Regards,
Andreas
next prev parent reply other threads:[~2020-12-09 20:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 9:57 [PATCH] spi: dt-bindings: clarify CS behavior for spi-cs-high and gpio descriptors H. Nikolaus Schaller
2020-12-09 17:36 ` Sven Van Asbroeck
2020-12-09 18:13 ` H. Nikolaus Schaller
2020-12-09 19:04 ` Sven Van Asbroeck
2020-12-09 19:31 ` H. Nikolaus Schaller
2020-12-09 20:01 ` Andreas Kemnade [this message]
2020-12-09 20:05 ` H. Nikolaus Schaller
2020-12-09 21:28 ` Sven Van Asbroeck
2020-12-09 22:04 ` H. Nikolaus Schaller
2020-12-11 13:18 ` Mark Brown
2020-12-11 13:26 ` Sven Van Asbroeck
2020-12-11 8:12 ` Linus Walleij
2020-12-11 17:51 ` Mark Brown
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