From: Daniel Vetter <daniel@ffwll.ch>
To: Marta Lofstedt <marta.lofstedt@intel.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 0/6] Rebase of David Herrmann drm connector link to backlight device
Date: Mon, 24 Oct 2016 16:33:44 +0200 [thread overview]
Message-ID: <20161024143344.GS20761@phenom.ffwll.local> (raw)
In-Reply-To: <20161024130853.13124-1-marta.lofstedt@intel.com>
On Mon, Oct 24, 2016 at 04:08:47PM +0300, Marta Lofstedt wrote:
> Hi David,
>
> I am currently investigating:
> https://bugs.freedesktop.org/show_bug.cgi?id=96572
>
> Martin Peres suggested that your patches:
> https://lists.freedesktop.org/archives/dri-devel/2014-September/thread.html#67984
> could solve the xf86-video-modesetting backlight issues.
>
> I have rebased your patches and I am working on an IGT
> test for the functionality. With my i915 implementation
> and the small included bug-fix, I can update the drm BACKLIGHT
> property and the value is updated in the backlight class device.
> However, if I set the brigness value through the sysfs file of
> the backlight class device the drm BRIGHTNESS property does not
> update which would be confusing to users.
>
> My understanding is that DRM properties are cached and, by design,
> do not have the capability to read the status from the driver.
>
> What do we want to do about this?
Fix it I'd say. But right now there's no callback for drivers to return
non-ATOMIC properties. Only old property values are cached like this. I
guess we can add a get_property hook, which is optional, and which would
fall back to the cached value if need. A bit a pain to wire up, but should
get the job done. Maybe just start out with a callback for connectors
only, instead of all kms objects which can have a property attached.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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prev parent reply other threads:[~2016-10-24 14:33 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-10 15:54 [PATCH RFC 0/4] Linking DRM Connectors to Backlight Devices David Herrmann
2014-09-10 15:54 ` [PATCH RFC 1/4] backlight: use static initializers David Herrmann
2014-09-11 8:59 ` Jani Nikula
2014-09-10 15:54 ` [PATCH RFC 2/4] backlight: use spin-lock to protect device list David Herrmann
2014-09-11 9:00 ` Jani Nikula
2014-09-10 15:54 ` [PATCH RFC 3/4] backlight: add kernel-internal backlight API David Herrmann
2014-09-11 11:10 ` Thierry Reding
2014-09-11 11:14 ` David Herrmann
2014-09-11 11:21 ` Thierry Reding
2014-09-10 15:54 ` [PATCH RFC 4/4] drm: link connectors to backlight devices David Herrmann
2014-09-11 6:48 ` Daniel Vetter
2014-09-11 12:22 ` David Herrmann
2014-09-11 13:06 ` Daniel Vetter
2014-09-11 16:07 ` David Herrmann
2014-09-11 12:46 ` Jani Nikula
2014-09-10 20:40 ` [PATCH RFC 0/4] Linking DRM Connectors to Backlight Devices Matthew Garrett
2014-09-11 12:48 ` David Herrmann
2016-10-24 13:08 ` [PATCH 0/6] Rebase of David Herrmann drm connector link to backlight device Marta Lofstedt
2016-10-24 13:08 ` [PATCH 1/6] backlight: use static initializers Marta Lofstedt
2016-10-24 13:08 ` [PATCH 2/6] backlight: use spin-lock to protect device list Marta Lofstedt
2016-10-24 13:08 ` [PATCH 3/6] backlight: add kernel-internal backlight API Marta Lofstedt
2016-10-24 13:08 ` [PATCH 4/6] drm: link connectors to backlight devices Marta Lofstedt
2016-10-24 13:08 ` [PATCH 5/6] i915: Use drm backlight Marta Lofstedt
2016-10-24 13:08 ` [PATCH 6/6] drm: drm_backlight use the connect value to set brightness property Marta Lofstedt
2016-10-24 14:33 ` Daniel Vetter [this message]
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