TWL6040 fails to initialize
Florian Vaussard
florian.vaussard at epfl.ch
Wed Feb 26 04:53:02 EST 2014
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,
>
>
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