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From: Daniel Vetter <daniel@ffwll.ch>
To: meteor <meteor@ms1.url.com.tw>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: Garbage on screen when switching resolution after BIOS post
Date: Tue, 4 Oct 2011 13:08:07 +0200	[thread overview]
Message-ID: <20111004110656.GA2923@phenom.ffwll.local> (raw)
In-Reply-To: <CADsGByqLjX==6tG6+k33taUN8UJQcBUjkQee+Pja=DXW7THraQ@mail.gmail.com>

On Tue, Oct 04, 2011 at 05:53:08PM +0800, meteor wrote:
> We are developing a Linux solution. Our platform is using Intel SandyBridge
> and its VGA
> (kernel 2.6.35.8, 915 KMS driver).
> 
> We found system will show garbage at the moment VGA is hand over to OS after
> BIOS POST.
> The symptom doesn’t happen in WIN 7.
> After checking with EE, the LCD_VDD_EN pin is pull low again when boot to
> Win 7.
> However, this pin is not pull low when boot to Linux.
> 
> After BIOS POST, there’s a power reset during driver loading for resolution
> pattern sending.
> It’s why driver needs to control PCH "L_VDD_EN" for power reset, and the
> panel spec suggests to
> have VDD power off  for >=500ms.
> 
> Please refer to the VDD power monitoring image:
> http://imageshack.us/photo/my-images/827/auoi.jpg/
> 
> Need help to fix the issue in driver.

Sounds like you need Keith's eDP power sequencing rework. Afaik you can
grab the latest version here:

http://cgit.freedesktop.org/~keithp/linux/log/?h=macbook-air

Testing feedback highly welcome (and with some details about the panel
type/hw, if possible).

Yours, Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48
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  reply	other threads:[~2011-10-04 11:07 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-04  9:53 Garbage on screen when switching resolution after BIOS post meteor
2011-10-04 11:08 ` Daniel Vetter [this message]
2011-10-04 15:38 ` Keith Packard

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