On Thu, Jun 23, 2022 at 4:00 AM Lino Sanfilippo <LinoSanfilippo@xxxxxx> wrote: > On 22.06.22 at 19:04, Andy Shevchenko wrote: > > On Wed, Jun 22, 2022 at 05:46:52PM +0200, Lino Sanfilippo wrote: > >> From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx> > >> > >> In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus > >> termination is supported by the driver. > > > > I'm not sure I got the usefulness of this change. > > We request GPIO line as optional, so if one is defined it in the DT/ACPI, then > > they probably want to (opportunistically) have it> > > > > With your change it's possible to have a DTS where GPIO line defined in a > > broken way and user won't ever know about it, if they are using platforms > > without termination support. > > This behavior is not introduced with this patch, also in the current code the driver > wont inform the user if it does not make use erroneous defined termination GPIO. It does. If a previously stale GPIO resource may have deferred a probe and hence one may debug why the driver is not working, after this change one may put a stale GPIO resource into DT/ACPI and have nothing in the result. Meaning the change relaxes validation which I consider is not good. > This patch at least prevents the driver from allocating and holding a GPIO descriptor across > the drivers lifetime that will never be used. But it's not your issue, if DTS defines it, so the platform has an idea about its usage. > Furthermore it simplifies the code in patch 2 when we want to set the GPIO, since we can > skip the check whether or not the termination GPIO is supported by the driver. That's fine. -- With Best Regards, Andy Shevchenko
