diff options
| author | Stefani Seibold <stefani@seibold.net> | 2011-01-03 12:28:59 +0300 |
|---|---|---|
| committer | Paul Mundt <lethal@linux-sh.org> | 2011-01-06 09:52:19 +0300 |
| commit | 748103e7235892bf9a3ee568d7d4dd7e5a3beece (patch) | |
| tree | 64e9ab69ea39b169d96df92cc2cf0073fb6617ed /drivers/video/i810/i810-i2c.c | |
| parent | 529ed806d4540d23ca2f68b28c3715d1566fc3ac (diff) | |
| download | linux-748103e7235892bf9a3ee568d7d4dd7e5a3beece.tar.xz | |
drivers/video/i810/i810-i2c.c: fix i2c bus handling
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.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'drivers/video/i810/i810-i2c.c')
| -rw-r--r-- | drivers/video/i810/i810-i2c.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/video/i810/i810-i2c.c b/drivers/video/i810/i810-i2c.c index cd2c728a809b..7db17d0d8a8c 100644 --- a/drivers/video/i810/i810-i2c.c +++ b/drivers/video/i810/i810-i2c.c @@ -45,8 +45,10 @@ static void i810i2c_setscl(void *data, int state) struct i810fb_par *par = chan->par; u8 __iomem *mmio = par->mmio_start_virtual; - i810_writel(mmio, chan->ddc_base, (state ? SCL_VAL_OUT : 0) | SCL_DIR | - SCL_DIR_MASK | SCL_VAL_MASK); + if (state) + i810_writel(mmio, chan->ddc_base, SCL_DIR_MASK | SCL_VAL_MASK); + else + i810_writel(mmio, chan->ddc_base, SCL_DIR | SCL_DIR_MASK | SCL_VAL_MASK); i810_readl(mmio, chan->ddc_base); /* flush posted write */ } @@ -56,8 +58,10 @@ static void i810i2c_setsda(void *data, int state) struct i810fb_par *par = chan->par; u8 __iomem *mmio = par->mmio_start_virtual; - i810_writel(mmio, chan->ddc_base, (state ? SDA_VAL_OUT : 0) | SDA_DIR | - SDA_DIR_MASK | SDA_VAL_MASK); + if (state) + i810_writel(mmio, chan->ddc_base, SDA_DIR_MASK | SDA_VAL_MASK); + else + i810_writel(mmio, chan->ddc_base, SDA_DIR | SDA_DIR_MASK | SDA_VAL_MASK); i810_readl(mmio, chan->ddc_base); /* flush posted write */ } |