linux-kernel - Re: [PATCH v8 4/4] serial: pl011: add console matching function

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Message-ID: <20160803083351.GD18515@xora-haswell.xora.org.uk>
Date:	Wed, 3 Aug 2016 09:33:51 +0100
From:	Graeme Gregory <gg@...mlogic.co.uk>
To:	Russell King - ARM Linux <linux@...linux.org.uk>
Cc:	Aleksey Makarov <aleksey.makarov@...aro.org>,
	"Zheng, Lv" <lv.zheng@...el.com>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	Peter Hurley <peter@...leysoftware.com>,
	Graeme Gregory <graeme.gregory@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	linux-kernel@...r.kernel.org,
	Leif Lindholm <leif.lindholm@...aro.org>,
	linux-acpi@...r.kernel.org,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	Yury Norov <ynorov@...iumnetworks.com>,
	Christopher Covington <cov@...eaurora.org>,
	linux-serial@...r.kernel.org, Mark Salter <msalter@...hat.com>,
	Al Stone <ahs3@...hat.com>,
	linux-arm-kernel@...ts.infradead.org, Len Brown <lenb@...nel.org>,
	Lorenzo.Pieralisi@....com, Sudeep.Holla@....com
Subject: Re: [PATCH v8 4/4] serial: pl011: add console matching function

On Mon, Jun 20, 2016 at 04:19:14PM +0100, Russell King - ARM Linux wrote:
> On Mon, Jun 20, 2016 at 03:26:39PM +0300, Aleksey Makarov wrote:
> > 
> > On 06/02/2016 09:02 PM, Aleksey Makarov wrote:
> > > 
> > > On 05/20/2016 04:03 PM, Aleksey Makarov wrote:
> > 
> > Hi Russell,
> > 
> > Can you review this patch please?
> > 
> > Thank you
> > Aleksey Makarov
> > 
> > >> This patch adds function pl011_console_match() that implements
> > >> method match of struct console.  It allows to match consoles against
> > >> data specified in a string, for example taken from command line or
> > >> compiled by ACPI SPCR table handler.
> > >>
> > >> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
> > >> Reviewed-by: Peter Hurley <peter@...leysoftware.com>
> > > 
> > > Hi Greg, Russell,
> > > 
> > > Can you review this patch and consider ACKing it please?
> > > It had an ACK from Greg in v7 but since then I changed it a bit.
> > > 
> > > The patch by Christopher Covington [1] specifies that SBSA uart 
> > > does 32-bit access to registers and this breaks the match function.  
> > > In this series the function was changed to match when SPCR specifies
> > > both mmio32 and mmio access.  I removed Acked-by: Greg from this
> > > patch because of these changes.
> > > 
> > > The difference between v7 and v8:
> > > 
> > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> > > index 4139b64..388edc8 100644
> > > --- a/drivers/tty/serial/amba-pl011.c
> > > +++ b/drivers/tty/serial/amba-pl011.c
> > > @@ -2328,10 +2329,10 @@ static int __init pl011_console_match(struct console *co, char *name, int idx,
> > >  
> > >                 port = &amba_ports[i]->port;
> > >  
> > > -               if (port->iotype != iotype)
> > > +               if (iotype != UPIO_MEM && iotype != UPIO_MEM32)
> > >                         continue;
> > > -               if ((iotype == UPIO_MEM || iotype == UPIO_MEM32) &&
> > > -                   (port->mapbase != addr))
> > > +
> > > +               if (port->mapbase != addr)
> > >                         continue;
> > >  
> > >                 co->index = i;
> 
> I'm looking at this change, and I don't know what effect it ultimately
> has.  This is kind of a problem, because I've zero knowledge of ACPI,
> and so I can't say whether this change is appropriate or not.  I have
> no ARM server platforms (yet), nor any access to them, so I can't even
> try it out.
> 
> In short, I've no idea.  I guess it's up to those who have come up
> with SBSA to decide whether this is an appropriate change or not.
> 

Lorenzo, Sudeep, as ARM ACPI maintainers and keepers of SBSA do you have
any comment on this?

Graeme