On Sat, Jan 28, 2012 at 5:07 AM, Jean Delvare <jdelvare at suse.de> wrote: > 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 <jdelvare at suse.de> > Acked-by: Eugeni Dodonov <eugeni.dodonov at intel.com> > Cc: Dave Airlie <airlied at gmail.com> > Cc: Keith Packard <keithp at keithp.com> > Cc: Alex Deucher <alexdeucher at gmail.com>
Reviewed-by: Alex Deucher <alexdeucher at gmail.com> > --- > Already sent on: 2011-10-21. > > ?drivers/gpu/drm/i915/intel_i2c.c ? ?| ? ?2 +- > ?drivers/gpu/drm/radeon/radeon_i2c.c | ? ?2 +- > ?2 files changed, 2 insertions(+), 2 deletions(-) > > --- linux-3.3-rc1.orig/drivers/gpu/drm/i915/intel_i2c.c 2012-01-28 > 10:12:16.554480007 +0100 > +++ linux-3.3-rc1/drivers/gpu/drm/i915/intel_i2c.c ? ? ?2012-01-28 > 10:28:16.884668894 +0100 > @@ -37,7 +37,7 @@ > > ?/* Intel GPIO access functions */ > > -#define I2C_RISEFALL_TIME 20 > +#define I2C_RISEFALL_TIME 10 > > ?static inline struct intel_gmbus * > ?to_intel_gmbus(struct i2c_adapter *i2c) > --- linux-3.3-rc1.orig/drivers/gpu/drm/radeon/radeon_i2c.c ? ? ?2012-01-28 > 10:12:16.555480007 +0100 > +++ linux-3.3-rc1/drivers/gpu/drm/radeon/radeon_i2c.c ? 2012-01-28 > 10:28:16.886668894 +0100 > @@ -924,7 +924,7 @@ 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
