Hi Alex, On Thu, 14 Apr 2011 19:47:06 -0400, Alex Deucher wrote: > Apparently some distros set i2c-algo-bit.bit_test to 1 by > default. In some cases this causes i2c_bit_add_bus > to fail and prevents the i2c bus from being added. In the > radeon case, we fail to add the ddc i2c buses which prevents > the driver from being able to detect attached monitors. > The i2c bus works fine even if bit_test fails. This is likely > due to gpio switching that is required and handled in the > pre/post_xfer hooks, so call the pre/post_xfer hooks in the > bit test as well. > > Fixes: > https://bugs.freedesktop.org/show_bug.cgi?id=36221 > > Cc: Jean Delvare <khali@xxxxxxxxxxxx> > Signed-off-by: Alex Deucher <alexdeucher@xxxxxxxxx> Good catch, applied, thanks. I'll also push this to the stable kernel trees (from .38 down to .34.) > --- > drivers/i2c/algos/i2c-algo-bit.c | 21 ++++++++++++++++++--- > 1 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c > index 38319a6..e2740e6 100644 > --- a/drivers/i2c/algos/i2c-algo-bit.c > +++ b/drivers/i2c/algos/i2c-algo-bit.c > @@ -232,9 +232,16 @@ static int i2c_inb(struct i2c_adapter *i2c_adap) > * Sanity check for the adapter hardware - check the reaction of > * the bus lines only if it seems to be idle. > */ > -static int test_bus(struct i2c_algo_bit_data *adap, char *name) > +static int test_bus(struct i2c_adapter *i2c_adap, char *name) > { > - int scl, sda; > + struct i2c_algo_bit_data *adap = i2c_adap->algo_data; > + int scl, sda, ret; > + > + if (adap->pre_xfer) { > + ret = adap->pre_xfer(i2c_adap); > + if (ret < 0) > + return -ENODEV; > + } > > if (adap->getscl == NULL) > pr_info("%s: Testing SDA only, SCL is not readable\n", name); > @@ -297,11 +304,19 @@ static int test_bus(struct i2c_algo_bit_data *adap, char *name) > "while pulling SCL high!\n", name); > goto bailout; > } > + > + if (adap->post_xfer) > + adap->post_xfer(i2c_adap); > + > pr_info("%s: Test OK\n", name); > return 0; > bailout: > sdahi(adap); > sclhi(adap); > + > + if (adap->post_xfer) > + adap->post_xfer(i2c_adap); > + > return -ENODEV; > } > > @@ -607,7 +622,7 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, > int ret; > > if (bit_test) { > - ret = test_bus(bit_adap, adap->name); > + ret = test_bus(adap, adap->name); > if (ret < 0) > return -ENODEV; > } -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
