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Date:   Wed, 9 Dec 2020 21:01:33 +0100
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
Message-ID: <20201209210133.44ab9c97@aktux>
In-Reply-To: <CAGngYiVL9M72hFRWnmT_8RRX9pUTSLsNuYz6mUo0Be4Vivk7Xw@mail.gmail.com>
References: <3bed61807fff6268789e7d411412fbc5cd6ffe2a.1607507863.git.hns@goldelico.com>
        <CAGngYiVKHoXPGxmScCnb-R6xoo9GNw5pG8V8Cpyk3meoJbskiw@mail.gmail.com>
        <3FA1D050-3BD5-4A97-9D83-520CCF75D147@goldelico.com>
        <CAGngYiVL9M72hFRWnmT_8RRX9pUTSLsNuYz6mUo0Be4Vivk7Xw@mail.gmail.com>
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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