From: Paul Mundt <lethal@linux-sh.org>
To: Stefani Seibold <stefani@seibold.net>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
linux-fbdev@vger.kernel.org, adaplas@gmail.com,
Maik Broemme <mbroemme@plusserver.de>,
Dave Airlie <airlied@linux.ie>
Subject: Re: [PATCH] fix i810 i2c bug
Date: Thu, 06 Jan 2011 06:53:29 +0000 [thread overview]
Message-ID: <20110106065329.GF15340@linux-sh.org> (raw)
In-Reply-To: <1294046939.20021.12.camel@wall-e>
On Mon, Jan 03, 2011 at 10:28:59AM +0100, Stefani Seibold wrote:
> These patch fix a longstanding bug in the i810 frame buffer driver.
>
> The handling of the i2c bus is wrong: A 1 bit should not written to the
> i2c, these will be done by switch the i2c to input. Driving an 1 bit
> active is against the i2c spec.
>
> An active driven of a 1 bit will result in very strange error, depending
> which side is the more powerful one. In my case it depends on the
> temperature of the Display-Controller-EEprom: With an cold eprom a got
> the correct EDID datas, with a warm one some of the 1 bits was 0 :-(
>
> The same bug is also in the intelfb driver in the file
> drivers/video/intelfb/intelfb_i2c.c. The functions intelfb_gpio_setscl()
> and intelfb_gpio_setsda() do drive the 1 bit active to the i2c bus. But
> since i have no card which is used by the intelfb driver i cannot fix
> it.
>
> The patch is against linux next-20101231
>
> - Stefani
>
> Signed-off-by: Stefani Seibold <stefani@seibold.net>
Applied, thanks.
Also adding intelfb people to the Cc so they're aware of the problem, and
can follow suit.
prev parent reply other threads:[~2011-01-06 6:53 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-03 9:28 [PATCH] fix i810 i2c bug Stefani Seibold
2011-01-06 6:53 ` Paul Mundt [this message]
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