Re: [PATCH v2 2/3] drivers/tty/serial/8250: add DT property for aspeed vuart sirq polarity

[Zev Weiss]

On Wed, Mar 31, 2021 at 11:15:44PM CDT, Joel Stanley wrote:
> On Thu, 1 Apr 2021 at 00:57, Zev Weiss <zev@xxxxxxxxxxxxxxxxx> wrote:
> > This provides a simple boolean to use instead of the deprecated
> > aspeed,sirq-polarity-sense property.
> >
> > Signed-off-by: Zev Weiss <zev@xxxxxxxxxxxxxxxxx>
> > ---
> >  drivers/tty/serial/8250/8250_aspeed_vuart.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> > index c33e02cbde93..e5ef9f957f9a 100644
> > --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
> > +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> > @@ -482,6 +482,9 @@ static int aspeed_vuart_probe(struct platform_device *pdev)
> >                 of_node_put(sirq_polarity_sense_args.np);
> >         }
> >
> > +       if (of_property_read_bool(np, "aspeed,sirq-active-high"))
> > +               aspeed_vuart_set_sirq_polarity(vuart, 1);
>
> This assumes the default is always low, so we don't need a property to
> set it to that state?
>
> Would it make more sense to have the property describe if it's high or
> low? (I'm happy for the answer to be "no", as we've gotten by for the
> past few years without it).

Yeah, that sounds like better way to approach it -- I think I'll 
rearrange as Andrew suggested in 
https://lore.kernel.org/openbmc/d66753ee-7db2-41e5-9fe5-762b1ab678bc@xxxxxxxxxxxxxxxx/

> This brings up another point. We already have the sysfs file for
> setting the lpc address, from userspace. In OpenBMC land this can be
> set with obmc-console-client (/etc/obmc-console.conf). Should we add
> support to that application for setting the irq polarity too, and do
> away with device tree descriptions?

I guess I might lean slightly toward keeping the DT description so that 
if for whatever reason obmc-console-server flakes out and doesn't start 
you're better positioned to try banging on /dev/ttyS* manually if you're 
desperate.  Though I suppose that in turn might imply that I'm arguing 
for adding DT properties for lpc_address and sirq too, and if you're 
really that desperate you can just fiddle with sysfs anyway, so...shrug?  
I could be convinced either way fairly easily.


Zev