Re: [RFC] SATA : Implemented NXP errata A008402

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 10 January 2018 at 09:43, Udit Kumar <udit.kumar@nxp.com> wrote:
> Hi Ruiyu,
>
>> -----Original Message-----
>> >
>> > And this change will not impact any other hardware so no one is basically
>> impacted by this change.
>>
>> Your buggy HW only need the value zero. But the addition of PCD exposes
>> an interface that can use any size of PRD.
>> I am not sure the AtaAtapiPassThru can work if some platform sets the PCD
>> value to others than 0 or 3F_FFFFh.
>
> I don't see someone using this driver will set Pcd randomly, but I agree on this
> point other value should be handled.
> Error or Assert could be added, if Pcd value is not 0 or 3F_FFFFh.
>
>> Can you please
>>   just duplicate the AtaAtapiPassThru in your platform?
>> Because the driver is very stable today, not much code sync effort will be
>> needed if core version is changed.
>
> Duplicating is always a possibility :), but When we will push this duplicated driver
> (just for one line change) for upstreaming.
> will this be acceptable ??

My main concern with this (and with using a PCD) is that the setting
affects all SATA controllers in the system, including ones the you
stick into a PCIe slot.

So I think forking the driver is the only possible solution, but it
will not be a one-line change: you need to ensure that you apply the
workaround only to the SATA controllers in the SoC.

-- 
Ard.