# Re: \[PATCH\] fix i810 i2c bug

- From: Paul Mundt \<hidden\>
- Date: 2011-01-06 06:55:28 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2011/01/3662357
- Thread: https://ratatoskr.run/linux-fbdev/2011/01/3660872/t.md

```text
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.
```