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

From: "Andrew Jeffery" <andrew@aj.id.au>
To: "Zev Weiss" <zev@bewilderbeest.net>, "Joel Stanley" <joel@jms.id.au>
Cc: linux-aspeed <linux-aspeed@lists.ozlabs.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	OpenBMC Maillist <openbmc@lists.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-serial@vger.kernel.org, Jiri Slaby <jirislaby@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 2/3] drivers/tty/serial/8250: add DT property for aspeed vuart sirq polarity
Date: Thu, 01 Apr 2021 16:04:04 +1030	[thread overview]
Message-ID: <06aee58f-819b-4486-a5ea-22e6d45e2be5@beta.fastmail.com> (raw)
In-Reply-To: <YGVXuyqOyxc8kcQz@hatter.bewilderbeest.net>

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@bewilderbeest.net> wrote:
> >>
> >> This provides a simple boolean to use instead of the deprecated
> >> aspeed,sirq-polarity-sense property.
> >>
> >> Signed-off-by: Zev Weiss <zev@bewilderbeest.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