Re: [PATCH v2] pwm: lpss: Make builtin so that i915 can find the pwm_backlight

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 20 Jan 2017, Mika Westerberg <mika.westerberg@linux.intel.com> 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?

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center
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