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, 1 Apr 2021 02:36:11 -0500
From:   Zev Weiss <zev@...ilderbeest.net>
To:     Andrew Jeffery <andrew@...id.au>
Cc:     Joel Stanley <joel@....id.au>, 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, Apr 01, 2021 at 12:34:04AM CDT, Andrew Jeffery wrote:
>
>
>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

Ah -- yes, that does sound like a sensible approach.  I'll send a v3 
with that worked in.


Zev