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Subject: Re: [BUG] SPI broken for SPI based panel drivers
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From:   "H. Nikolaus Schaller" <hns@goldelico.com>
In-Reply-To: <CAGngYiVF5yMAGPJ8xZgt=BfJ3JfBMABVC0t+dQ2oOq986T9iKg@mail.gmail.com>
Date:   Tue, 1 Dec 2020 18:10:17 +0100
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Discussions about the Letux Kernel 
        <letux-kernel@openphoenux.org>,
        Andreas Kemnade <andreas@kemnade.info>
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To:     Sven Van Asbroeck <thesven73@gmail.com>
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Hi Sven,

> Am 01.12.2020 um 17:53 schrieb Sven Van Asbroeck =
<thesven73@gmail.com>:
>=20
> Hi Nikolaus,
>=20
> On Tue, Dec 1, 2020 at 11:43 AM H. Nikolaus Schaller =
<hns@goldelico.com> wrote:
>>=20
>> You are right. It is active low.
>>=20
>=20
> In that case, we have a very simple solution, just remove the =
spi-cs-high,
> and things will work.

We originally had it that way and because there was a change in gpiolib =
we had
to introduce it.

See: f1f028ff89cb0d3

where we were forced to introduce it although I had preferred to not =
change DT.

I am not sure if DT maintainers accept that we revert a DT change just =
to
handle some change in a driver. Usually they insist on fixing a driver =
and
live with the DT. DT is carved in stone or could be ROM...

So you could try to submit a revert of f1f028ff89cb0d3 with a =
description
why it is needed. And please make sure that it is also applied where =
your
patch is backported to stable. So it should have some

Fixes: 766c6b63aa04 ("spi: fix client driver breakages when using GPIO =
descriptors")

>=20
> In case of SPI CS gpios, the current kernel ignores all
> GPIO_ACTIVE_HIGH/LOW
> flags, and uses the presence/absence of spi-cs-high instead, to
> determine active high / active low.

So you mean you are just restoring the behaviour before

	6953c57ab172

was introduced?

The alternative is that you restore the cs-gpios + spi-cs-high semantics
as defined by 6953c57ab172 and everything is fine without touching (our)
DTS (again).

BR and thanks,
Nikolaus