[PATCH] modules/firmware: add a new option to denote a firmware group to choose one.

[Lucas De Marchi]

On Wed, Apr 19, 2023 at 02:36:52PM +1000, Dave Airlie wrote:
>From: Dave Airlie <airlied at redhat.com>
>
>This adds a tag that will go into the module info, only one firmware from
>the group given needs to be available for this driver to work. This allows
>dracut to avoid adding in firmware that aren't needed.
>
>This just brackets a module list in the modinfo, the modules in the list
>will get entries in reversed order so the last module in the list is the
>preferred one.
>
>The corresponding dracut code it at:
>https://github.com/dracutdevs/dracut/pull/2309

it would be good to have the example usage in the commit message here so
it can be easily checked as reference for other drivers.

I don't think we ever had any ordering in modinfo being relevant for
other things. Considering the use case and that we could also use a
similar thing for i915 / xe modules wrt to the major version,
couldn't we do something like below?

	MODULE_FIRMWARE_GROUP("nvidia/ga106/gsp/gsp");
	MODULE_FIRMWARE("nvidia/ga106/gsp/gsp-5258902.bin");
	MODULE_FIRMWARE("nvidia/ga106/gsp/gsp-5303002.bin");

so the group is created by startswith() rather than by the order the
modinfo appears in the elf section. In i915 we'd have:

MODULE_FIRMWARE_GROUP("i915/tgl_guc")

There is still an order the kernel would probably like: latest version.
But then it's an order only among things with the same key.

Lucas De Marchi

>
>Cc: Luis Chamberlain <mcgrof at kernel.org>
>Cc: linux-modules at vger.kernel.org
>Cc: dri-devel at lists.freedesktop.org
>Signed-off-by: Dave Airlie <airlied at redhat.com>
>---
> include/linux/module.h | 2 ++
> 1 file changed, 2 insertions(+)
>
>diff --git a/include/linux/module.h b/include/linux/module.h
>index 4435ad9439ab..f02448ed5e2b 100644
>--- a/include/linux/module.h
>+++ b/include/linux/module.h
>@@ -289,6 +289,8 @@ extern typeof(name) __mod_##type##__##name##_device_table		\
>  * files require multiple MODULE_FIRMWARE() specifiers */
> #define MODULE_FIRMWARE(_firmware) MODULE_INFO(firmware, _firmware)
>
>+#define MODULE_FIRMWARE_GROUP_ONLY_ONE(_grpname) MODULE_INFO(firmware_group_only_one, _grpname)
>+
> #define MODULE_IMPORT_NS(ns)	MODULE_INFO(import_ns, __stringify(ns))
>
> struct notifier_block;
>-- 
>2.39.2
>