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From: Takashi Iwai <tiwai@suse.de>
To: Keith Packard <keithp@keithp.com>
Cc: Daniel Mack <zonque@gmail.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Jesse Barnes <jbarnes@virtuousgeek.org>,
	harald@redhat.com, intel-gfx@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/i915: Fix invalid backpanel values for GEN3 or older chips
Date: Sun, 20 Nov 2011 12:22:50 +0100	[thread overview]
Message-ID: <s5hd3cn3unp.wl%tiwai@suse.de> (raw)
In-Reply-To: <867h2wklln.fsf@sumi.keithp.com>

At Sat, 19 Nov 2011 10:34:12 -0800,
Keith Packard wrote:
> 
> [1  <text/plain (quoted-printable)>]
> On Sat, 19 Nov 2011 11:05:05 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> 
> > Maybe it'd be better to mention that actually setting bit-0 caused a
> > blank screen on some machines.
> 
> Was that caused by *just* setting bit zero? Or was it caused by setting
> the duty cycle to 0xffff, in which case it would be larger than the
> maximum value?
> 
> I'll clean up the commit log message with your answer and then push this out.

According to Daniels' original post:

On 11/04/2011 03:36 PM, Daniel Mack wrote:
> I'm facing a bug on a Samsung X20 notebook which features an i915
> chipset (output of 'lspci -v' attached).
>
> The effect is that setting the backlight to odd values causes the value
> to be misinterpreted. Harald Hoyer (cc:) had the same thing on a Netbook
> (I don't recall which model it was).
>
> So this will turn the backlight to full brightness:
>
> # cat /sys/class/backlight/intel_backlight/max_brightness
> 29750
> # echo 29750 > /sys/class/backlight/intel_backlight/brightness
>
> However, writing 29749 will turn the display backlight off, and 29748
> appears to be the next valid lower value.

So, writing bit-0 caused a problem, as it seems.


Takashi

WARNING: multiple messages have this Message-ID (diff)
From: Takashi Iwai <tiwai@suse.de>
To: Keith Packard <keithp@keithp.com>
Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Daniel Mack <zonque@gmail.com>,
	harald@redhat.com
Subject: Re: [PATCH] drm/i915: Fix invalid backpanel values for GEN3 or older chips
Date: Sun, 20 Nov 2011 12:22:50 +0100	[thread overview]
Message-ID: <s5hd3cn3unp.wl%tiwai@suse.de> (raw)
In-Reply-To: <867h2wklln.fsf@sumi.keithp.com>

At Sat, 19 Nov 2011 10:34:12 -0800,
Keith Packard wrote:
> 
> [1  <text/plain (quoted-printable)>]
> On Sat, 19 Nov 2011 11:05:05 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> 
> > Maybe it'd be better to mention that actually setting bit-0 caused a
> > blank screen on some machines.
> 
> Was that caused by *just* setting bit zero? Or was it caused by setting
> the duty cycle to 0xffff, in which case it would be larger than the
> maximum value?
> 
> I'll clean up the commit log message with your answer and then push this out.

According to Daniels' original post:

On 11/04/2011 03:36 PM, Daniel Mack wrote:
> I'm facing a bug on a Samsung X20 notebook which features an i915
> chipset (output of 'lspci -v' attached).
>
> The effect is that setting the backlight to odd values causes the value
> to be misinterpreted. Harald Hoyer (cc:) had the same thing on a Netbook
> (I don't recall which model it was).
>
> So this will turn the backlight to full brightness:
>
> # cat /sys/class/backlight/intel_backlight/max_brightness
> 29750
> # echo 29750 > /sys/class/backlight/intel_backlight/brightness
>
> However, writing 29749 will turn the display backlight off, and 29748
> appears to be the next valid lower value.

So, writing bit-0 caused a problem, as it seems.


Takashi

  reply	other threads:[~2011-11-20 11:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-16 17:14 [PATCH] drm/i915: Fix invalid backpanel values for GEN3 or older chips Takashi Iwai
2011-11-17  6:15 ` Keith Packard
2011-11-17  6:15   ` Keith Packard
2011-11-17 16:33   ` Takashi Iwai
2011-11-17 17:14     ` Daniel Mack
2011-11-18 19:25     ` Keith Packard
2011-11-19  9:33       ` Daniel Mack
2011-11-19 10:05       ` Takashi Iwai
2011-11-19 10:05         ` Takashi Iwai
2011-11-19 18:34         ` Keith Packard
2011-11-20 11:22           ` Takashi Iwai [this message]
2011-11-20 11:22             ` Takashi Iwai
2011-11-21 18:10             ` Keith Packard
2011-11-22 16:40               ` Daniel Mack
2011-11-22 17:54                 ` Keith Packard
2012-04-12  1:59             ` James
2012-04-12  6:54               ` [PATCH] drm/i915: Fix invalid backpanel values for?GEN3 " Daniel Vetter

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