linux-kernel - Re: [PATCH] arm_mpam: Fix T241-MPAM-4 workaround

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Message-ID: <c7c4bd25-5fcb-43a7-9f89-389e50784e07@nvidia.com>
Date: Wed, 18 Sep 2024 00:12:11 +0800
From: Koba Ko <kobak@...dia.com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Shanker Donthineni <sdonthineni@...dia.com>
Cc: James Morse <james.morse@....com>,
 Catalin Marinas <catalin.marinas@....com>,
 Rohit Mathew <rohit.mathew@....com>, linux-arm-kernel@...ts.infradead.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 Vikram Sethi <vsethi@...dia.com>
Subject: Re: [PATCH] arm_mpam: Fix T241-MPAM-4 workaround


On 8/21/24 19:42, Jonathan Cameron wrote:
> On Mon, 19 Aug 2024 17:08:18 -0500
> Shanker Donthineni <sdonthineni@...dia.com> wrote:
>
>> The workaround for T241-MPAM-4 was applied incorrectly, leading to
>> MBW_MIN being programmed with a zero value when the user specifies
>> MBW_MAX is less than 5%.
>>
>> This patch ensures that MBW_MIN is programmed with a non-zero value,
>> set to 1 to fix the T241-MPAM-4 as expected.
>>
>> Fixes: 13ff1b527e40 ("arm_mpam: Add workaround for T241-MPAM-4")
>> Signed-off-by: Shanker Donthineni <sdonthineni@...dia.com>
> Hi Shanker,
>
> I can guess which branch this fix is for, but good to mention it
> in the patch given it's not mainline.
>
> Jonathan
Hi Jonathan,
could you please share the cgit of branch?
Thanks
>> ---
>>   drivers/platform/arm64/mpam/mpam_devices.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/mpam_devices.c
>> index a802ca1c9f05..e49a27c02c66 100644
>> --- a/drivers/platform/arm64/mpam/mpam_devices.c
>> +++ b/drivers/platform/arm64/mpam/mpam_devices.c
>> @@ -2990,7 +2990,7 @@ static void mpam_extend_config(struct mpam_class *class, struct mpam_config *cfg
>>   	}
>>   
>>   	if (mpam_has_quirk(T241_FORCE_MBW_MIN_TO_ONE, class) &&
>> -	    cfg->mbw_min == 0) {
>> +	    cfg->mbw_min <= min_hw_granule) {
>>   		cfg->mbw_min = min_hw_granule + 1;
>>   		mpam_set_feature(mpam_feat_mbw_min, cfg);
>>   	}
>