Re: [PATCH v2] ata: add AMD Seattle platform driver

From: Brijesh Singh
Date: Fri Mar 18 2016 - 14:40:14 EST

Hi Tejun,

On 03/17/2016 12:36 PM, Arnd Bergmann wrote:
> On Wednesday 16 March 2016 14:07:13 Tejun Heo wrote:
>> Hello, Arnd.
>> On Mon, Feb 01, 2016 at 09:14:17PM +0100, Arnd Bergmann wrote:
>>>> I am not debating on your AML call recommendation, it sounds like
>>>> a good idea however BIOS is already released hence its bit late to
>>>> add AML methods for this. I am seeking guidance on what can be
>>>> done in the given situation. I thought platform driver is one
>>>> option to get this feature enabled in kernel.
>>> This is where we really need the ACPI maintainers to explain the
>>> general policy for dealing with firmware updates.
>>> I would assume that adding the feature in a later firmware version
>>> is a compatible change, and the feature is non-essential (the
>>> device will work fine with the generic SATA driver, except
>>> the LEDs don't blink), so it's not a big deal, it's just what
>>> you get for having the firmware shipped before the driver is
>>> reviewed (don't do that).
>> So, if it were x86, I'd commit the custom driver without thinking too
>> much as ata drivers have always been working around bios issues (there
>> often wasn't any other recourse). If the hardware is already out
>> there and it's not too easy to roll out bios updates, from libata
>> side, I'm okay with having a custom driver to work around that. What
>> do you think?
> It's your call in the end. My main objection is to the fact that
> I have suggested a clean implementation for the normal DT based
> path that also fixes existing platforms that used to work in the
> past and were broken by the (long-ago) move from drivers/ide to
> drivers/ata, Brijesh has not implemented that but has instead
> continued pushing the hack for the ACPI mode that is still
> experimental on ARM64.

I am helping a customer who want EM support in a distro (using ACPI mode). Since its difficult to update
the bios hence can I request to pull this driver. The driver solves the ACPI usecases.

As per DT is concerned, will look into driver/ide and led framework but since I am not very familiar with
driver/ide and led framework hence it will take sometime to design and implement the DT cases.

> Arnd