RE: [PATCH v1 2/2] usb:cdns3 Add Cadence USB3 DRD Driver

From: Felipe Balbi
Date: Mon Dec 17 2018 - 06:56:39 EST


Pawel Laszczak <pawell@xxxxxxxxxxx> writes:
>>>>> +static irqreturn_t cdns3_device_irq_handler(int irq, void *data)
>>>>> +{
>>>>> + struct cdns3_device *priv_dev;
>>>>> + struct cdns3 *cdns = data;
>>>>> + irqreturn_t ret = IRQ_NONE;
>>>>> + unsigned long flags;
>>>>> + u32 reg;
>>>>> +
>>>>> + priv_dev = cdns->gadget_dev;
>>>>> + spin_lock_irqsave(&priv_dev->lock, flags);
>>>>you're already running in hardirq context. Why do you need this lock at
>>>>all? I would be better to use the hardirq handler to mask your
>>>>interrupts, so they don't fire again, then used the top-half (softirq)
>>>>handler to actually handle the interrupts.
>>> Yes, spin_lock_irqsave is not necessary here.
>>> Do you mean replacing devm_request_irq with a request_threaded_irq ?
>>> I have single interrupt line shared between Host, Driver, DRD/OTG.
>>> I'm not sure if it will work more efficiently.
>>The whole idea for running very little in hardirq context is to give the
>>scheduler a chance to decide what should run. This is important to
>>reduce latency when running with RT patchset applied, for
>>example. However, I'll give you that, it's a minor requirement. It's
>>just that, to me, it's a small detail that's easy to implement.
> I will do it in PATCH v2 or PATCH v3.
> I need to post next version before 24 of December, so if I can do it
> before this date then it will be in PATCH v2.

Take your time :-) Nothing will happen until next year. I already sent
my pull request for v4.21 and a large chunk of the community takes a few
days off during the holiday season.

There's really no rush from a community stand point.


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