linux-kernel - Re: [PATCH v1 1/1] ACPI: CPPC: Fix access width used for PCC registers

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Message-ID: <694fdd96-cc6e-4a4e-aff5-3284cd3ada4e@linux.microsoft.com>
Date: Mon, 8 Apr 2024 22:28:34 -0700
From: Easwar Hariharan <eahariha@...ux.microsoft.com>
To: Jarred White <jarredwhite@...ux.microsoft.com>,
 Vanshidhar Konda <vanshikonda@...amperecomputing.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
 linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] ACPI: CPPC: Fix access width used for PCC
 registers

On 4/8/2024 1:19 PM, Jarred White wrote:
> On 4/1/2024 10:45 AM, Vanshidhar Konda wrote:
>> On Mon, Apr 01, 2024 at 09:48:28AM -0700, Easwar Hariharan wrote:
>>> Hi Vanshi,
>>>
>>> Thanks for testing and catching this. One comment below, but Jarred is OOF for a couple days so
>>> we'll get back again after testing on our platform.
>>>
>>> On 3/29/2024 3:00 PM, Vanshidhar Konda wrote:
>>>> Commit 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for
>>>> system memory accesses") modified cpc_read/cpc_write to use access_width to
>>>> read CPC registers. For PCC registers the access width field in the ACPI
>>>> register macro specifies the PCC subspace id. For non-zero PCC subspace id
>>>> the access width is incorrectly treated as access width. This causes errors
>>>> when reading from PCC registers in the CPPC driver.
>>>>
>>>> For PCC registers base the size of read/write on the bit width field.
>>>> The debug message in cpc_read/cpc_write is updated to print relevant
>>>> information for the address space type used to read the register.
>>>>
>>>> Fixes: 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for system memory accesses")
>>>> Signed-off-by: Vanshidhar Konda <vanshikonda@...amperecomputing.com>
>>>> ---

Hi Vanshi,

When you send v2 for the SystemMemory space fixes, could you add CC: stable@...r.kernel.org # 5.15+
to your commit message, since your patch fixes 2f4a4d63a193 that was marked for stable?

Thanks,
Easwar