linux-kernel - Re: [PATCH v2] ACPI: LPSS: use acpi_dev_uid_match() for matching

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Message-ID: <ZTuMo2qDO6Aqq3D_@black.fi.intel.com>
Date:   Fri, 27 Oct 2023 13:11:56 +0300
From:   Raag Jadav <raag.jadav@...el.com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     rafael@...nel.org, len.brown@...el.com,
        andriy.shevchenko@...ux.intel.com, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        mallikarjunappa.sangannavar@...el.com, bala.senthil@...el.com
Subject: Re: [PATCH v2] ACPI: LPSS: use acpi_dev_uid_match() for matching _UID

On Fri, Oct 27, 2023 at 11:18:55AM +0300, Mika Westerberg wrote:
> On Thu, Oct 26, 2023 at 02:03:35PM +0530, Raag Jadav wrote:
> > Now that we have a standard ACPI helper, we can use acpi_dev_uid_match()
> > for matching _UID as per the original logic before commit 2a036e489eb1
> > ("ACPI: LPSS: Refactor _UID handling to use acpi_dev_uid_to_integer()"),
> > instead of treating it as an integer.
> > 
> > Signed-off-by: Raag Jadav <raag.jadav@...el.com>
> > Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> 
> The change still looks good to me, however I wonder if we could maybe
> improve acpi_dev_uid_match() to support both data types possible for
> _UID? This of course is separate patch (unless there are objections).
> 
> There is the _Generic() thing and I think that can be used to make
> 
>   acpi_dev_uid_match()
> 
> which takes either u64 (or maybe even unsigned int) or const char * and
> based on that picks the correct implementation. Not sure if that's
> possible, did not check but it would allow us to use one function
> everywhere instead of acpi_dev_uid_to_integer() and
> acpi_dev_uid_match().

The way I see it, acpi_dev_uid_to_integer() is useful when drivers want to
parse _UID and store it in their private data, so that it is available for
making various decisions throughout the lifetime of the driver, as opposed
to acpi_dev_uid_match() which is more useful for oneshot comparisons in my
opinion.

So I'm a bit conflicted about merging them into a single helper, unless
ofcourse there is a way to serve both purposes.

However, I do agree that we can improve acpi_dev_uid_match() by treating
uids as integers underneath, instead of doing a raw string comparison.
This would make it more aligned with the spec as suggested by Andy.

Raag