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

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Date:   Thu, 01 Apr 2021 16:04:04 +1030
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Zev Weiss" <zev@...ilderbeest.net>,
        "Joel Stanley" <joel@....id.au>
Cc:     "Jeremy Kerr" <jk@...abs.org>,
        "OpenBMC Maillist" <openbmc@...ts.ozlabs.org>,
        "Linux ARM" <linux-arm-kernel@...ts.infradead.org>,
        linux-aspeed <linux-aspeed@...ts.ozlabs.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Jiri Slaby" <jirislaby@...nel.org>, linux-serial@...r.kernel.org
Subject: Re: [PATCH v2 2/3] drivers/tty/serial/8250: add DT property for aspeed vuart sirq polarity



On Thu, 1 Apr 2021, at 15:48, Zev Weiss wrote:
> On Wed, Mar 31, 2021 at 11:15:44PM CDT, Joel Stanley wrote:
> >On Thu, 1 Apr 2021 at 00:57, Zev Weiss <zev@...ilderbeest.net> wrote:
> >>
> >> This provides a simple boolean to use instead of the deprecated
> >> aspeed,sirq-polarity-sense property.
> >>
> >> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
> >> ---
> >>  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@www.fastmail.com/
> 
> >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,

Why not just adopt exactly what I've done with KCS, where we have aspeed,lpc-io-reg and aspeed,lpc-interrupts?

Andrew