From: Tony Lindgren <tony@atomide.com>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: "Benoît Cousson" <bcousson@baylibre.com>,
"Rob Herring" <robh+dt@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
broonie@kernel.org, linus.walleij@linaro.org,
stable@vger.kernel.org, linux-spi@vger.kernel.org,
linux-omap@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org,
kernel@pyra-handheld.com
Subject: Re: [PATCH v2] DTS: ARM: gta04: introduce legacy spi-cs-high to make display work again
Date: Mon, 23 Sep 2019 10:34:41 -0700 [thread overview]
Message-ID: <20190923173441.GV5610@atomide.com> (raw)
In-Reply-To: <c031340840daba810bb2a612c35eea7fab307e56.1568995874.git.hns@goldelico.com>
* H. Nikolaus Schaller <hns@goldelico.com> [190920 09:12]:
> commit 6953c57ab172 "gpio: of: Handle SPI chipselect legacy bindings"
>
> did introduce logic to centrally handle the legacy spi-cs-high property
> in combination with cs-gpios. This assumes that the polarity
> of the CS has to be inverted if spi-cs-high is missing, even
> and especially if non-legacy GPIO_ACTIVE_HIGH is specified.
>
> The DTS for the GTA04 was orginally introduced under the assumption
> that there is no need for spi-cs-high if the gpio is defined with
> proper polarity GPIO_ACTIVE_HIGH.
>
> This was not a problem until gpiolib changed the interpretation of
> GPIO_ACTIVE_HIGH and missing spi-cs-high.
>
> The effect is that the missing spi-cs-high is now interpreted as CS being
> low (despite GPIO_ACTIVE_HIGH) which turns off the SPI interface when the
> panel is to be programmed by the panel driver.
>
> Therefore, we have to add the redundant and legacy spi-cs-high property
> to properly activate CS.
Thanks applying into fixes.
Tony
prev parent reply other threads:[~2019-09-23 17:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 16:11 [PATCH v2] DTS: ARM: gta04: introduce legacy spi-cs-high to make display work again H. Nikolaus Schaller
2019-09-23 17:34 ` Tony Lindgren [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190923173441.GV5610@atomide.com \
--to=tony@atomide.com \
--cc=bcousson@baylibre.com \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=hns@goldelico.com \
--cc=kernel@pyra-handheld.com \
--cc=letux-kernel@openphoenux.org \
--cc=linus.walleij@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=robh+dt@kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).