Messages in this thread |  | | From | Alexandre Courbot <> | Date | Thu, 23 Oct 2014 14:10:19 +0900 | Subject | Re: [PATCH v8 3/4] gpiolib: add irq_not_threaded flag to gpio_chip |
| |
On Mon, Oct 20, 2014 at 7:19 PM, Octavian Purdila <octavian.purdila@intel.com> wrote: > On Mon, Oct 20, 2014 at 8:08 AM, Alexandre Courbot <gnurou@gmail.com> wrote: >> >> On Wed, Oct 15, 2014 at 11:48 PM, Octavian Purdila >> <octavian.purdila@intel.com> wrote: >> > Some GPIO chips (e.g. the DLN2 USB adapter) have blocking get/set >> > operation but do not need a threaded irq handler. >> >> Sorry if you already explained this (I have been a little bit late >> with the GPIO reviews recently), but does this optimization bring a >> significant benefit that justifies adding another field in struct >> gpio_chip? If so it would be nice to have it in the commit message. If >> not, do we need this at all? > > Hi Alexandre, > > In the case DLN2 USB GPIO adapter the GPIO interrupt is generated in > the completion routine of a receive URB, which means that we are in > interrupt context. If a threaded irq is used, we would have to > schedule work instead of running to interrupt handler directly which > is unnecessary and adds latency. > > BTW, AFAIC Linus W already merged this patch in his next tree, I am > keeping it in this series because it was not pulled in the mfd-next > tree.
You're right, it's all good then. Thanks for the explanation.
|  |