Hi, First, thanks for your help. On 02/26/2014 08:26 AM, Peter Ujfalusi wrote: > On 02/25/2014 05:41 PM, Florian Vaussard wrote: >> If the power was not enabled at all, I would be unable to read the >> revision register, no? And delaying the probe by one millisecond would >> be of no help in this case IMHO. > > One thing which might cause this is that if the audpwron GPIO is set high > before the twl6040 module is probing. When I request the GPIO I ask it to be > set to low. If the line was high before this means we initiate the power off > sequence. > Can you try something like this: > I statistically checked that the sleep should be placed after the GPIO request, so indeed this seems to be the problem, and your explanation is plausible. Can you send a proper patch? Now, related to this, I managed to found a part of the datasheet on the Great Internet. Looking at the "Power-Up Sequence" section, it is written: - NRESPWRON goes high -> plug detect and GPO are available - V2V1 goes high -> hook-detect available by I2C programming (sleep mode) - AUDPWRON goes high && READYINT -> ready to communicate through I2C and PDM So, although there seems to be some contradictions on when it is possible to access the I2C, shouldn't we enable the AUDPWRON GPIO _before_ making any I2C access? For the twl6040_probe, the following path would seem more correct to me: 1) enable regulators 2) request AUDPWRON 3) twl6040_power(ON) && regcache_cache_only(false) 4) wait for READYINT (or sleep if deterministic) 5) perform all required I2C accesses (read revision, etc.) 6) twl6040_power(OFF) && regcache_cache_only(true) What do you think? Thanks, Florian > diff --git a/drivers/mfd/twl6040.c b/drivers/mfd/twl6040.c > index 75316fb33448..d2a0bd1539ae 100644 > --- a/drivers/mfd/twl6040.c > +++ b/drivers/mfd/twl6040.c > @@ -674,6 +674,9 @@ static int twl6040_probe(struct i2c_client *client, > GPIOF_OUT_INIT_LOW, "audpwron"); > if (ret) > goto gpio_err; > + > + /* power-down sequence latency */ > + usleep_range(500, 700); > } > > ret = regmap_add_irq_chip(twl6040->regmap, twl6040->irq, IRQF_ONESHOT, > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
