linux-kernel - Re: [PATCH] acpi: Use access_width over register

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Message-ID: <42a5c36d-8b65-418f-9826-2808ab49d67a@linux.microsoft.com>
Date:   Wed, 11 Oct 2023 12:56:40 -0700
From:   Jarred White <jarredwhite@...ux.microsoft.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Len Brown <lenb@...nel.org>,
        "open list:ACPI" <linux-acpi@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] acpi: Use access_width over register_width for system
 memory accesses

On 10/3/2023 11:50 AM, Rafael J. Wysocki wrote:
 > On Mon, Sep 25, 2023 at 8:06 PM Jarred White
 > <jarredwhite@...ux.microsoft.com> wrote:
 >> To align with ACPI 6.3+, since bit_width can be any 8-bit value, we 
cannot
 >> depend on it being always on a clean 8b boundary. Instead, use 
access_width
 >> to determine the size and use the offset and width to shift and mask the
 >> bit swe want to read/write out. Make sure to add a check for system 
memory
 >> since pcc redefines the access_width to subspace id.
 > This is fine, but what if there are systems in the field where
 > bit_width is invalid, but they just happen to work because of the way
 > it is currently handled?
For the kernel coding style issues, I will clean up for the v2 patch.

On the invalid bit_width for systems out there in the field, do you have 
any suggestions on how to handle this particular scenario? Would it be 
appropriate to add a kernel parameter flag that can revert back to the 
previous implementation?

P.S. Sorry for the HTML email.


Thanks,
Jarred