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From: "H. Nikolaus Schaller" <hns@goldelico.com>
To: Sven Van Asbroeck <thesven73@gmail.com>
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>
Subject: Re: [BUG] SPI broken for SPI based panel drivers
Date: Tue, 1 Dec 2020 18:10:17 +0100	[thread overview]
Message-ID: <BD3995F3-F4E6-4DC9-B0B9-5DCD6655F049@goldelico.com> (raw)
In-Reply-To: <CAGngYiVF5yMAGPJ8xZgt=BfJ3JfBMABVC0t+dQ2oOq986T9iKg@mail.gmail.com>

Hi Sven,

> Am 01.12.2020 um 17:53 schrieb Sven Van Asbroeck <thesven73@gmail.com>:
> 
> Hi Nikolaus,
> 
> On Tue, Dec 1, 2020 at 11:43 AM H. Nikolaus Schaller <hns@goldelico.com> wrote:
>> 
>> You are right. It is active low.
>> 
> 
> 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")

> 
> 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


  reply	other threads:[~2020-12-01 17:13 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-30 19:03 [BUG] SPI broken for SPI based panel drivers H. Nikolaus Schaller
2020-11-30 20:13 ` Sven Van Asbroeck
2020-11-30 20:22   ` Sven Van Asbroeck
2020-12-01  8:59   ` H. Nikolaus Schaller
2020-12-01 12:16     ` Mark Brown
2020-12-01 14:05       ` H. Nikolaus Schaller
2020-12-01 14:20         ` Linus Walleij
2020-12-01 14:34           ` Sven Van Asbroeck
2020-12-01 14:35           ` H. Nikolaus Schaller
2020-12-01 15:52             ` Sven Van Asbroeck
2020-12-01 16:46               ` H. Nikolaus Schaller
2020-12-01 16:10             ` Sven Van Asbroeck
2020-12-01 16:39               ` H. Nikolaus Schaller
2020-12-01 16:53                 ` Sven Van Asbroeck
2020-12-01 17:10                   ` H. Nikolaus Schaller [this message]
2020-12-01 18:43                     ` Sven Van Asbroeck
2020-12-02 12:19                       ` Mark Brown
2020-12-04 10:08                       ` H. Nikolaus Schaller
2020-12-04 13:46                         ` Sven Van Asbroeck
2020-12-04 16:49                           ` H. Nikolaus Schaller
2020-12-04 19:19                             ` Sven Van Asbroeck
2020-12-04 21:31                               ` H. Nikolaus Schaller
2020-12-05  0:25                             ` Linus Walleij
2020-12-05  7:04                               ` H. Nikolaus Schaller
2020-12-09  8:04                                 ` Andreas Kemnade
2020-12-09  8:40                                   ` H. Nikolaus Schaller
2020-12-09  8:38                                 ` Linus Walleij
2020-12-09  8:45                                   ` H. Nikolaus Schaller
2020-12-01 22:51                     ` Linus Walleij
2020-12-01 16:44               ` [Letux-kernel] " Andreas Kemnade
2020-12-01 16:51                 ` H. Nikolaus Schaller
2020-12-01 16:52                 ` H. Nikolaus Schaller
2020-12-01 16:55                 ` Sven Van Asbroeck
2020-12-01 16:20           ` Mark Brown
2020-12-01 16:41             ` H. Nikolaus Schaller
2020-12-01 17:11               ` Mark Brown
2020-12-01 12:41     ` Sven Van Asbroeck
2020-12-01 13:32       ` H. Nikolaus Schaller
2020-12-01 14:08         ` Sven Van Asbroeck
2020-12-01 15:33           ` Mark Brown
2020-12-05 20:57   ` Pavel Machek
2020-12-07 13:43     ` Mark Brown

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