> -----Original Message----- > From: Andy Shevchenko [mailto:andy.shevchenko@xxxxxxxxx] > Sent: 2022年3月22日 16:45 > To: Bough Chen <haibo.chen@xxxxxxx> > Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>; Bartosz Golaszewski > <brgl@xxxxxxxx>; open list:GPIO SUBSYSTEM <linux-gpio@xxxxxxxxxxxxxxx>; > Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; dl-linux-imx > <linux-imx@xxxxxxx> > Subject: Re: [PATCH v2] gpio: Allow setting gpio device id via device tree alias > > On Tue, Mar 22, 2022 at 7:52 AM <haibo.chen@xxxxxxx> wrote: > > > > From: Haibo Chen <haibo.chen@xxxxxxx> > > > > For some SoCs which contain different cores, like few ARM A cores and > > few ARM M cores. Some GPIO controllers like GPIO3/GPIO4/GPIO5 belong > > to A core domain, some GPIO controllers like GPIO1/GPIO2 belong to M > > core domain. Linux only cover A cores, without gpio alias, we can get > > gpiochip0/gpiochip1/gpiochip2 to map the real GPIO3/GPIO4/GPIO5, it's > > difficult for users to identify this map relation, and hardcode the > > gpio device index. With gpio alias, > > With the GPIO > > > we can easily make gpiochip3 map to GPIO3, gpiochip4 map to GPIO4. > > For GPIO controllers do not claim the alias, it will get one id > > If GPIO > > > which larger than all the claimed aliases. > > which is > > ... > > I'm not sure I understand the issue. The other GPIO drivers and hence user > space (which is already quite a question why user space needs > this) may distinguish the GPIO chips by labels and device names. > What's wrong with that approach? For users, usually, they will open /dev/gpiochipx to handle gpio related option. By the way, how can user get the labels and device names of GPIO chips? Best Regards Haibo Chen > > -- > With Best Regards, > Andy Shevchenko
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