From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mundt Date: Thu, 06 Jan 2011 06:53:29 +0000 Subject: Re: [PATCH] fix i810 i2c bug Message-Id: <20110106065329.GF15340@linux-sh.org> List-Id: References: <1294046939.20021.12.camel@wall-e> In-Reply-To: <1294046939.20021.12.camel@wall-e> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Stefani Seibold Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-fbdev@vger.kernel.org, adaplas@gmail.com, Maik Broemme , Dave Airlie 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 Applied, thanks. Also adding intelfb people to the Cc so they're aware of the problem, and can follow suit.