A udelay value of 20 leads to an I2C bus running at only 25 kbps. I2C
devices can typically operate faster than this, 50 kbps should be fine
for all devices (and compliant devices can always stretch the clock if
needed.)
FWIW, the vast majority of framebuffer drivers set udelay to 10
already. So set it to 10 in DRM drivers too, this will make EDID block
reads faster. We might even lower the udelay value later if no problem
is reported.
Signed-off-by: Jean Delvare <jdelv...@suse.de>
Reviewed-by: Alex Deucher <alexdeuc...@gmail.com>
Cc: Dave Airlie <airl...@gmail.com>
---
Changes since v1:
* Split per driver to make merging easier.
* Make the subject line more accurate.
drivers/gpu/drm/radeon/radeon_i2c.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- linux-3.4-rc0.orig/drivers/gpu/drm/radeon/radeon_i2c.c 2012-03-21
13:43:33.753915151 +0100
+++ linux-3.4-rc0/drivers/gpu/drm/radeon/radeon_i2c.c 2012-03-21
13:48:01.619472673 +0100
@@ -925,7 +925,7 @@ struct radeon_i2c_chan *radeon_i2c_creat
i2c->algo.bit.setscl = set_clock;
i2c->algo.bit.getsda = get_data;
i2c->algo.bit.getscl = get_clock;
- i2c->algo.bit.udelay = 20;
+ i2c->algo.bit.udelay = 10;
/* vesa says 2.2 ms is enough, 1 jiffy doesn't seem to always
* make this, 2 jiffies is a lot more reliable */
i2c->algo.bit.timeout = 2;
--
Jean Delvare
Suse L3
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