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From: Sven Van Asbroeck <thesven73@gmail.com>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Lukas Wunner <lukas@wunner.de>, 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: Fri, 4 Dec 2020 08:46:33 -0500	[thread overview]
Message-ID: <CAGngYiUPaR=_1NKZSjUQRK9+zUw3ztUpro7NV-O=sGAC2eOzUw@mail.gmail.com> (raw)
In-Reply-To: <A88317FA-52CC-41D3-B11A-BFAD36C35AE4@goldelico.com>

On Fri, Dec 4, 2020 at 5:11 AM H. Nikolaus Schaller <hns@goldelico.com> wrote:
>
> Anyways it is debatable if this is a bug at all. It is just a definition.

I respectfully disagree. Prior to the fix, your panel's active-low chip select
needed to be described in the devicetree with 'spi-cs-high'. That sounds
very much like a bug to me.

> Which is not well documented anywhere.

I agree that documentation can be improved here.
Would you like to submit a patch that improves:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/spi/spi-controller.yaml?h=v5.10-rc6#n28
?
This way, we also get Rob Herring involved, which may lead to more elegant
documentation. He is more likely to respond to a patch than to a question.

>
> What I especially wonder is why you fix that at all in drivers/spi/spi.c
> if polarity inversion is handled in gpiolib.

The reason for that is described in the commit message of
766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors")

  reply	other threads:[~2020-12-04 13:47 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
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 [this message]
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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