linux-kernel - Re: [PATCH] i2c: add i2c bus driver for amd navi gpu

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Message-ID: <YF26F8IFmbo80rMq@smile.fi.intel.com>
Date:   Fri, 26 Mar 2021 12:40:23 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "Goswami, Sanket" <Sanket.Goswami@....com>
Cc:     jarkko.nikula@...ux.intel.com, mika.westerberg@...ux.intel.com,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>
Subject: Re: [PATCH] i2c: add i2c bus driver for amd navi gpu

On Fri, Mar 26, 2021 at 03:53:34PM +0530, Goswami, Sanket wrote:
> On 25-Mar-21 22:35, Andy Shevchenko wrote:
> > On Mon, Mar 22, 2021 at 10:26:55PM +0530, Goswami, Sanket wrote:
> >> On 09-Mar-21 19:56, Andy Shevchenko wrote:
> >>> On Tue, Mar 09, 2021 at 07:01:47PM +0530, Sanket Goswami wrote:

...

> > And I think I already have told you that I prefer to see rather MODEL_ quirk.
> 
> I did not find MODEL_ quirk reference in the PCI device tree, It is actually
> used in platform device tree which is completely different from our PCI
> based configuration, can you please provide some reference of MODEL_ quirk
> which will be part of the PCI device tree?

I meant the name of new definition for quirk.

...

> >>> Also why (1) and this can't be instantiated from ACPI / DT?
> >> It is in line with the existing PCIe-based DesignWare driver,
> >> A similar approach is used by the various vendors.
> > 
> > Here is no answer to the question. What prevents you to fix your ACPI tables or
> > DT?
> > 
> > We already got rid of FIFO hard coded values, timings are harder to achieve,
> > but we expect that new firmwares will provide values in the ACPI tables.
> 
> AMD NAVI GPU card is the PCI initiated driver, not ACPI initiated,

Which doesn't prevent to have an ACPI companion (via description in the
tables).

> and also
> It does not contain a corresponding ACPI match table.

Yes, that's what should be done in the firmware.
At least for the new version of firmware consider to add proper data into the
tables.

> Moreover, AMD  NAVI GPU
> based products are already in the commercial market hence going by this
> approach will break the functionalities for the same.

This is quite bad and unfortunate. So, you have to elaborate this in the commit
message.

-- 
With Best Regards,
Andy Shevchenko