From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: Gordon Hollingworth <gordon@raspberrypi.org>,
Eric Anholt <eric@anholt.net>
Cc: David Airlie <airlied@linux.ie>,
Thierry Reding <thierry.reding@gmail.com>,
afaerber@suse.de, agraf@suse.de, dri-devel@lists.freedesktop.org,
linux-kernel@vger.kernel.org,
linux-rpi-kernel@lists.infradead.org, stefan.wahren@i2se.com
Subject: Re: [PATCH v2] drm/panel: rpi-touchscreen: Add backlight support
Date: Thu, 20 Dec 2018 20:06:45 +0100 [thread overview]
Message-ID: <3df5afdfe9fe709fad1a4ae565692028c437beed.camel@suse.de> (raw)
In-Reply-To: <CAPLZx4kd9RZtUKySDhk9RHOWPL2P=GG_g0GP3NweZ-UR-a3MSQ@mail.gmail.com>
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On Thu, 2018-12-20 at 18:36 +0000, Gordon Hollingworth wrote:
> Assuming this is using the firmware interface then yes it's fine. If
> it is using the i2c directly then it's possible to clash with the GPU
> driving the camera
Well we're already in such a situation without this patch, as the panel
enables the back-light though the I2C lines. This is only enabled by an
overlay, it's left to the user's discretion.
As commented previously by Alex Graf and given the constraints, I think
that it would make sense to start considering both options as good
(using FW & direct I2C access). We are defaulting to the FW based one,
but providing support/overlays for the direct access doesn't seem a bad
compromise to me.
I do understand Gordon's concerns. Maybe it would be nice for the
firmware to detect device tree nodes accessing I2C0 and disable the
camera. Or providing a FW configuration option.
Kind regards,
Nicolas
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prev parent reply other threads:[~2018-12-20 19:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-19 11:20 [PATCH v2] drm/panel: rpi-touchscreen: Add backlight support Nicolas Saenz Julienne
2018-12-20 18:32 ` Eric Anholt
[not found] ` <CAPLZx4kd9RZtUKySDhk9RHOWPL2P=GG_g0GP3NweZ-UR-a3MSQ@mail.gmail.com>
2018-12-20 19:06 ` Nicolas Saenz Julienne [this message]
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