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

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Message-ID: <365b430b-d91c-4391-bfc4-ea6a3444cb43@linux.microsoft.com>
Date: Mon, 8 Apr 2024 13:19:00 -0700
From: Jarred White <jarredwhite@...ux.microsoft.com>
To: Vanshidhar Konda <vanshikonda@...amperecomputing.com>,
 Easwar Hariharan <eahariha@...ux.microsoft.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 4/1/2024 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,

The patch is good.

You can add,
Reviewed-by: Jarred White <jarredwhite@...ux.microsoft.com>
Tested-by: Jarred White <jarredwhite@...ux.microsoft.com>

We also found another bug in the process of testing, which we will 
submitting a patch for.


Thanks,
Jarred