linux-kernel - Re: [PATCH v2 2/2] serial: 8250_dw: add ACPI support for uart on Hisilicon Hip05 soc

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Date:	Thu, 30 Jun 2016 17:39:46 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Kefeng Wang <wangkefeng.wang@...wei.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, z.liuxinliang@...ilicon.com,
	guohanjun@...wei.com, linux-acpi@...r.kernel.org,
	xuwei5@...ilicon.com, graeme.gregory@...aro.org
Subject: Re: [PATCH v2 2/2] serial: 8250_dw: add ACPI support for uart on
 Hisilicon Hip05 soc

On Thu, 2016-06-30 at 22:26 +0800, Kefeng Wang wrote:
> 
> On 2016/6/30 17:54, Andy Shevchenko wrote:
> > On Thu, 2016-06-30 at 12:38 +0300, Andy Shevchenko wrote:
> > > On Thu, 2016-06-30 at 09:27 +0800, Kefeng Wang wrote:
> > > > Add ACPI identifier for UART on Hisilicon Hip05 soc, be careful
> > > > that it is not 16550 compatibal.
> > > > 
> > > > Meanwhile, set dw8250_serial_out32 to keep consistent between
> > > > serial_out
> > > > and serial_in in ACPI.
> > > > 
> > > > Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> > > > ---
> > > >  drivers/tty/serial/8250/8250_dw.c | 13 +++++++++++--
> > > >  1 file changed, 11 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/tty/serial/8250/8250_dw.c
> > > > b/drivers/tty/serial/8250/8250_dw.c
> > > > index 65f3da7..096431b 100644
> > > > --- a/drivers/tty/serial/8250/8250_dw.c
> > > > +++ b/drivers/tty/serial/8250/8250_dw.c
> > > > @@ -272,6 +272,12 @@ static bool dw8250_idma_filter(struct
> > > > dma_chan
> > > > *chan, void *param)
> > > >  	return param == chan->device->dev->parent;
> > > >  }
> > > >  
> > > > +/* non 16550 compatible id list*/
> > > > +static const struct acpi_device_id non_16550_id_list[] = {
> > > > +	{ "HISI0031", 0 },
> > > > +	{ },
> > > > +};
> > > > +
> > > 
> > > On first glance it looks redundant, see below.
> > 
> > Oh, wait, this is still valid, but the better solution is to use
> > device
> > properties for the rest except yours!
> 
> Do you mean using something like
> 
> static struct property_entry dw8250_properties[] = {
>         PROPERTY_ENTRY_U32("reg-io-width", 4),
>         PROPERTY_ENTRY_U32("reg-shift", 2),
>         PROPERTY_ENTRY_BOOL("snps,uart-16550-compatible"),
>         { },
> };
> 
> then use platform_device_add_properties to add it to the device(16500
> compatible),

Correct for the existing devices.

> 
> but for hisi, use another property_entry without
> PROPERTY_ENTRY_BOOL("snps,uart-16550-compatible")?

For HISI in case of alternate configuration you have to tweak _DSD in
ACPI.

> 
> Not clear about using device properties.

Built-in device properties only for non-DT, non-ACPI devices. You may
consider it as a successor of platform data.

> 
> > 
> > I will prepare patch later this week or at the beginning of next
> > week if
> > you are in hurry, otherwise I would postpone this a bit (anyway it
> > will
> > not make v4.8 cycle).
> > 
> 
> Thanks, hope that it will come out soon.
> 

-- 

Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy