Messages in this thread | | | From | Bartosz Golaszewski <> | Date | Tue, 24 Dec 2019 13:08:41 +0100 | Subject | Re: [PATCH v3 12/13] gpiolib: add new ioctl() for monitoring changes in line info |
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czw., 19 gru 2019 o 19:17 Andy Shevchenko <andy.shevchenko@gmail.com> napisał(a): > > On Thu, Dec 19, 2019 at 7:17 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote: > > > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > Currently there is no way for user-space to be informed about changes > > in status of GPIO lines e.g. when someone else requests the line or its > > config changes. We can only periodically re-read the line-info. This > > is fine for simple one-off user-space tools, but any daemon that provides > > a centralized access to GPIO chips would benefit hugely from an event > > driven line info synchronization. > > > > This patch adds a new ioctl() that allows user-space processes to reuse > > the file descriptor associated with the character device for watching > > any changes in line properties. Every such event contains the updated > > line information. > > > > Currently the events are generated on three types of status changes: when > > a line is requested, when it's released and when its config is changed. > > The first two are self-explanatory. For the third one: this will only > > happen when another user-space process calls the new SET_CONFIG ioctl() > > as any changes that can happen from within the kernel (i.e. > > set_transitory() or set_debounce()) are of no interest to user-space. > > > - } else if (cmd == GPIO_GET_LINEINFO_IOCTL) { > > + } else if (cmd == GPIO_GET_LINEINFO_IOCTL || > > + cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) { > > Wouldn't be better for maintenance to have them separated from the day 1? >
I think this would lead to a lot of code duplication. I left it as it is is v4.
Bart
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