Hi,
On 08-03-17 10:40, Jani Nikula wrote:
On Fri, 20 Jan 2017, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
On Fri, Jan 20, 2017 at 10:02:50AM +0200, Jani Nikula wrote:
That said, I suppose there could be an alternative to handling pwm_get()
failures at probe. We could just go on with our init, but schedule a
retry later. Perhaps a bit hacky, but it would address both of the
concerns above. Again, this patch seems a simple workaround in the mean
time.
Not sure if this works or how hacky it is, but can't you
request_module() before you start looking up for the pwm?
I eyeballed this a little, and noticed:
drivers/acpi/acpi_lpss.c:
static struct pwm_lookup bsw_pwm_lookup[] = {
PWM_LOOKUP_WITH_MODULE("80862288:00", 0, "0000:00:02.0",
"pwm_backlight", 0, PWM_POLARITY_NORMAL,
"pwm-lpss-platform"),
};
drivers/mfd/intel_soc_pmic_core.c:
static struct pwm_lookup crc_pwm_lookup[] = {
PWM_LOOKUP("crystal_cove_pwm", 0, "0000:00:02.0", "pwm_backlight", 0, PWM_POLARITY_NORMAL),
};
Should crc_pwm_lookup also use PWM_LOOKUP_WITH_MODULE? And which module
exactly? pwm_get() does an automatic request_module(), if the module is
given.
And will this still be enough?
I was thinking about this a couple of days ago, unfortunately the
situation with pwm_crc is more complicated as that is part of
an i2c mfd device, so both the i2c-adapter driver and the mfd driver
(intel_soc_pmic_crc) need to be builtin currently the mfd driver
cannot be modular, but the i2c-adapter driver can (and on most
Linux distribution kernels is) configured to be modular.
So just doing request module for pwm-crc is not going to help
since the i2c-adapter driver may not yet have loaded / initialized.
All in all we really need to find a way to figure out if we will need
to do a pwm_get earlier on during i915 initialization (by moving the
VBT parsing to earlier, or at least part of it) and do the pwm_get
before we do anything i-reversible and if it fails then return
-EPROBE_DEFER. Then we can make pwm_crc modular as well as all of
intel_soc_pmic* as it really should be.
Regards,
Hans
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