From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Sebastian Reichel <sre@kernel.org>
Cc: "Tony Lindgren" <tony@atomide.com>,
"Benoît Cousson" <bcousson@baylibre.com>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
"Rob Herring" <robh+dt@kernel.org>,
devicetree@vger.kernel.org, linux-omap@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] ARM: dts: omap3-n900: fix LCD reset line polarity
Date: Tue, 11 Oct 2022 07:06:40 -0700 [thread overview]
Message-ID: <Y0V4cLGbYe4j+ls6@google.com> (raw)
In-Reply-To: <20221011123726.elsr53ue7nxzhvww@mercury.elektranox.org>
Hi Sebastian,
On Tue, Oct 11, 2022 at 02:37:26PM +0200, Sebastian Reichel wrote:
> Hi,
>
> On Tue, Oct 11, 2022 at 08:45:54AM +0300, Tony Lindgren wrote:
> > * Dmitry Torokhov <dmitry.torokhov@gmail.com> [221004 21:26]:
> > > The LCD driver (panel-sony-acx565akm), when probing, starts with line
> > > driven low, and then toggles it to high and keeps it there. Also, the
> > > line is driven low when powering off the device, and ls released when
> > > powering it back on. This means that the reset line should be described
> > > as "active low" in DTS. This will be important when the driver is
> > > converted to gpiod API which respects the polarity declared in DTS.
> >
> > We should ensure these patches get merged together with the driver
> > change to avoid breaking LCD for booting. Probably no need to have
> > the driver quirk handling for inverted polartity in this case.
> >
> > It's probably easiest to have an immutable branch for the driver
> > changes I can base the dts changes on. Or I can ack the dts changes
> > if they get merged with the driver.
>
> Both drivers are already using gpiod API:
>
> drivers/gpu/drm/panel/panel-sony-acx565akm.c
> drivers/gpu/drm/panel/panel-dsi-cm.c
I was looking at
drivers/video/fbdev/omap2/omapfb/displays/panel-sony-acx565akm.c
drivers/video/fbdev/omap2/omapfb/displays/panel-dsi-cm.c
which are not using gpiod. Should they be retired?
>
> So this just breaks things.
I missed the drivers in drivers/gpu/... and I see that they essentially
abuse gpiod API as gpiod_set_value() operates on logical level
(active/inactive) and not absolute (high/low). They should either use
the gpiod_*_raw() variants, or they should be adjusted to do the proper
thing together with the accompanying DTS change.
What are your preferences?
Thanks.
--
Dmitry
next prev parent reply other threads:[~2022-10-11 14:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-04 21:35 [PATCH 1/4] ARM: dts: omap3-n900: fix LCD reset line polarity Dmitry Torokhov
2022-10-04 21:35 ` [PATCH 2/4] ARM: dts: omap4-sdp: " Dmitry Torokhov
2022-10-04 21:35 ` [PATCH 3/4] ARM: dts: omap3-n950: " Dmitry Torokhov
2022-10-04 21:35 ` [PATCH 4/4] ARM: dts: motorola-mapphone: " Dmitry Torokhov
2022-10-11 5:45 ` [PATCH 1/4] ARM: dts: omap3-n900: " Tony Lindgren
2022-10-11 12:37 ` Sebastian Reichel
2022-10-11 14:06 ` Dmitry Torokhov [this message]
2022-10-11 14:30 ` Tony Lindgren
2022-10-11 14:38 ` Dmitry Torokhov
2022-10-11 14:47 ` Tony Lindgren
2022-10-12 10:58 ` Tomi Valkeinen
2022-10-12 19:30 ` Dmitry Torokhov
2022-10-13 6:22 ` Tomi Valkeinen
2022-10-13 11:08 ` Tony Lindgren
2022-10-13 13:17 ` Sebastian Reichel
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