linux-kernel - Re: max PWM is zero

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Date:	Tue, 22 Nov 2011 00:38:58 -0200
From:	Lucas De Marchi <lucas.de.marchi@...il.com>
To:	Keith Packard <keithp@...thp.com>
Cc:	Marcos Paulo de Souza <marcos.mage@...il.com>,
	linux-kernel@...r.kernel.org, airlied@...ux.ie,
	dri-devel@...ts.freedesktop.org
Subject: Re: max PWM is zero

On Mon, Nov 21, 2011 at 23:40, Keith Packard <keithp@...thp.com> wrote:
> On Mon, 21 Nov 2011 22:48:21 +0000 (Local time zone must be set--see zic manual page), Marcos Paulo de Souza <marcos.mage@...il.com> wrote:
>
>> My max_brightness is 1, and my brightness is 0.
>
> Right, we've prevented the internal backlight driver from exposing a max
> value of 0 as that's just confusing.
>
>> But, my acpi_video0 have a
>> max_brightness value = 9...
>
> Right, sounds like your device is just using some other backlight
> controller, which is perfectly reasonable.
>
>> So, what can I do to silence this warning...? Change the driver of
>> backlight?
>
> If your backlight keys work correctly, then things are fine and perhaps
> we should just remove the warning from the driver, or disable the
> internal driver when we discover this situation.
>
> This is the first time I've heard of this warning appearing...

It appears here as well. I think it was since 2.6.39 or 3.0, I'm not sure.

Same card:

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series
Chipset Integrated Graphics Controller (rev 07) (prog-if 00 [VGA
controller])
	Subsystem: Dell Device 02bb
	Flags: bus master, fast devsel, latency 0, IRQ 45
	Memory at f6400000 (64-bit, non-prefetchable) [size=4M]
	Memory at d0000000 (64-bit, prefetchable) [size=256M]
	I/O ports at 1800 [size=8]
	Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
	Capabilities: [d0] Power Management version 3
	Kernel driver in use: i915

00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset
Integrated Graphics Controller (rev 07)
	Subsystem: Dell Device 02bb
	Flags: bus master, fast devsel, latency 0
	Memory at f6100000 (64-bit, non-prefetchable) [size=1M]
	Capabilities: [d0] Power Management version 3

My kernel log has:

[drm] Driver supports precise vblank timestamp query.
composite sync not supported
fixme: max PWM is zero.
composite sync not supported


Is this "composite sync not supported" related to this issue?


Lucas De Marchi
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