On 09/04/2014 at 20:37:06 +0100, Russell King - ARM Linux wrote : > On Wed, Apr 09, 2014 at 08:04:08PM +0200, Alexandre Belloni wrote: > > Adds a period and a polarity member to struct pwm_lookup so that when performing > > a lookup using the lookup table instead of device tree, we are able to set the > > period and the polarity accordingly like what is done in > > of_pwm_xlate_with_flags. > > > > Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> > > --- > > drivers/pwm/core.c | 5 +++++ > > include/linux/pwm.h | 2 ++ > > 2 files changed, 7 insertions(+) > > > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > > index a80471399c20..206e5996359c 100644 > > --- a/drivers/pwm/core.c > > +++ b/drivers/pwm/core.c > > @@ -663,6 +663,11 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) > > > > if (chip) > > pwm = pwm_request_from_chip(chip, index, con_id ?: dev_id); > > + if (IS_ERR(pwm)) > > + return pwm; > > + > > + pwm_set_period(pwm, p->period); > > + pwm_set_polarity(pwm, p->polarity); > > > > mutex_unlock(&pwm_lookup_lock); > > Clearly, this is not right. Returning while leaving the mutex locked? > No. > Sure, I will fix that crap, sorry about that and thanks for pointing it out. > The second issue is... with _just_ this patch applied, we end up with > "period" and "polarity" presumably initialised to zero, which means we > now end up with the above explicitly setting the period and polarity as > such. Isn't that going to change the behaviour of this? > I actually checked that. For the polarity, for now, it is assumed that it is normal unless specified otherwise. The only driver that was supporting inverting it using platform_data is pwm-renesas-tpu. It is used by board-armadillo800eva.c that I am modifying now (and I just now realise that I forgot to invert it). The only PWM controller that I know of that by default has its polarity inversed is the allwinner one and in the driver I submitted, I actually switch it to normal polarity in the probe instead of e.g. doing pwm->polarity = PWM_POLARITY_INVERSED; For the period, all the driver are assuming 0 after initialization. I think this is not specified. If you think that may be a concern then I suggest creating another macro and using a bitfield to know which value is set. I would also argue that when using device tree, of_pwm_xlate_with_flags() will set the period and the polarity unconditionally, this is replicating that behaviour. However, I could agree that we may need to test for pwm->chip->ops->set_polarity before calling pwm_set_polarity as we will get an error if it is NULL (but we actually discard that return value). -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- 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
