linux-kernel - Re: [PATCH 16/34] iio: ad5755: hook up of_device

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Message-ID: <20240406163013.76e4646e@jic23-huawei>
Date: Sat, 6 Apr 2024 16:30:13 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: "Arnd Bergmann" <arnd@...db.de>
Cc: "Krzysztof Kozlowski" <krzysztof.kozlowski@...aro.org>, "Arnd Bergmann"
 <arnd@...nel.org>, linux-kernel@...r.kernel.org, "Lars-Peter Clausen"
 <lars@...afoo.de>, "Michael Hennerich" <Michael.Hennerich@...log.com>,
 linux-iio@...r.kernel.org
Subject: Re: [PATCH 16/34] iio: ad5755: hook up of_device_id lookup to
 platform driver

On Wed, 03 Apr 2024 12:01:13 +0200
"Arnd Bergmann" <arnd@...db.de> wrote:

> On Wed, Apr 3, 2024, at 11:55, Krzysztof Kozlowski wrote:
> > On 03/04/2024 10:06, Arnd Bergmann wrote:  
> >> From: Arnd Bergmann <arnd@...db.de>
> >> 
> >> When the driver is built-in, 'make W=1' warns about an unused
> >> ID table:
> >> 
> >> drivers/iio/dac/ad5755.c:866:34: error: 'ad5755_of_match' defined but not used [-Werror=unused-const-variable=]
> >>   866 | static const struct of_device_id ad5755_of_match[] = {
> >> 
> >> While the data is duplicated in the spi_device_id, it's common
> >> to use the actual OF compatible strings in the driver.
> >> 
> >> Since there are no in-tree users of plain platform devices, the
> >> spi_device_id table could actually be dropped entirely with this.
> >> 
> >> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> >> ---
> >>  drivers/iio/dac/ad5755.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >> 
> >> diff --git a/drivers/iio/dac/ad5755.c b/drivers/iio/dac/ad5755.c
> >> index 404865e35460..5c1e7f428c25 100644
> >> --- a/drivers/iio/dac/ad5755.c
> >> +++ b/drivers/iio/dac/ad5755.c
> >> @@ -876,6 +876,7 @@ MODULE_DEVICE_TABLE(of, ad5755_of_match);
> >>  static struct spi_driver ad5755_driver = {
> >>  	.driver = {
> >>  		.name = "ad5755",
> >> +		.of_match_table = ad5755_of_match,  
> >
> > I was working on this as well and have a bit bigger solution, following
> > Jonathan's preference (I think):
> >
> > https://lore.kernel.org/all/20240226192555.14aa178e@jic23-huawei/
> >
> > I need to send v3, somehow I missed his comments.  
> 
> Yes, that looks good as well, though you might need to drop
> spi_device_id table if you convert it to using pointers.

Put them in there as well (with appropriate cast). We don't want
to stop supporting probe paths that might be using that.

My preference is for both tables, same pointers in each then
the use of the relevant bus specific wrapper - here
spi_get_device_match_data() which will happily deal with matches
in either table (thus avoiding the potential mess of them getting out
of sync)

Jonathan


> 
>      Arnd