linux-kernel - Re: [PATCH 2/2] ALSA: hda: cirrus

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Message-ID: <874jjpwd4i.wl-tiwai@suse.de>
Date:   Wed, 20 Sep 2023 08:51:57 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Richard Fitzgerald <rf@...nsource.cirrus.com>, tiwai@...e.com,
        alsa-devel@...a-project.org, patches@...nsource.cirrus.com,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH 2/2] ALSA: hda: cirrus_scodec: Add KUnit test

On Tue, 19 Sep 2023 22:44:28 +0200,
Nick Desaulniers wrote:
> 
> On Mon, Sep 18, 2023 at 10:51:29AM +0100, Richard Fitzgerald wrote:
(snip)
> > +static void cirrus_scodec_test_set_gpio_ref_arg(struct software_node_ref_args *arg,
> > +						int gpio_num)
> > +{
> > +	struct software_node_ref_args template =
> > +		SOFTWARE_NODE_REFERENCE(&cirrus_scodec_test_gpio_swnode, gpio_num, 0);
> 
> I'm observing the following error when building with:
> 
> $ make LLVM=1 -j128 allmodconfig sound/pci/hda/cirrus_scodec_test.o
> 
> sound/pci/hda/cirrus_scodec_test.c:151:60: error: initializer element is not a compile-time constant
>   151 |                 SOFTWARE_NODE_REFERENCE(&cirrus_scodec_test_gpio_swnode, gpio_num, 0);
>       |                                                                          ^~~~~~~~
> /builds/linux/include/linux/property.h:291:37: note: expanded from macro 'SOFTWARE_NODE_REFERENCE'
>   291 |         .nargs = ARRAY_SIZE(((u64[]){ 0, ##__VA_ARGS__ })) - 1, \
>       |                                            ^~~~~~~~~~~
> /builds/linux/include/linux/kernel.h:57:75: note: expanded from macro 'ARRAY_SIZE'
>    57 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>       |                                                                           ^~~
> /builds/linux/include/linux/compiler.h:228:59: note: expanded from macro '__must_be_array'
>   228 | #define __must_be_array(a)      BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
>       |                                                                ^
> /builds/linux/include/linux/compiler_types.h:366:63: note: expanded from macro '__same_type'
>   366 | #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
>       |                                                               ^
> /builds/linux/include/linux/build_bug.h:16:62: note: expanded from macro 'BUILD_BUG_ON_ZERO'
>    16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
>       |                                                              ^

Hm, this looks like some inconsistent handling of the temporary array
passed to ARRAY_SIZE() in the SOFTWARE_NODE_REFERENCE macro.  LLVM
can't treat it if it contains a variable in the given array, while GCC
doesn't care.

A hackish workaround would be the patch like below, but it's really
ugly.  Ideally speaking, it should be fixed in linux/properties.h, but
I have no idea how to fix there for LLVM.

Adding more relevant people to Cc.


thanks,

Takashi

--- a/sound/pci/hda/cirrus_scodec_test.c
+++ b/sound/pci/hda/cirrus_scodec_test.c
@@ -148,8 +148,9 @@ static void cirrus_scodec_test_set_gpio_ref_arg(struct software_node_ref_args *a
 						int gpio_num)
 {
 	struct software_node_ref_args template =
-		SOFTWARE_NODE_REFERENCE(&cirrus_scodec_test_gpio_swnode, gpio_num, 0);
+		SOFTWARE_NODE_REFERENCE(&cirrus_scodec_test_gpio_swnode, 0, 0);
 
+	template.args[0] = gpio_num;
 	*arg = template;
 }