linux-kernel - Re: [PATCH v2 1/6] gpio: exar: Fix passing in of parent PCI device

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Message-ID: <7d5b0099-b4d9-881d-fc63-0c7f8229e096@siemens.com>
Date:   Sun, 21 May 2017 13:44:17 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>,
        Sascha Weisenberger <sascha.weisenberger@...mens.com>
Subject: Re: [PATCH v2 1/6] gpio: exar: Fix passing in of parent PCI device

On 2017-05-18 19:14, Andy Shevchenko wrote:
> On Thu, May 18, 2017 at 5:59 PM, Jan Kiszka <jan.kiszka@...mens.com> wrote:
>> This fixes reloading of the GPIO driver for the same platform device
>> instance as created by the exar UART driver: First of all, the driver
>> sets drvdata to its own value during probing and does not restore the
>> original value on exit. But this won't help anyway as the core clears
>> drvdata after the driver left.
>>
>> Use stable platform_data instead.
> 
> Okay, basically what we are trying to do here is to reinvent part of
> MFD framework.
> 
> I'd like to hear Linus' and others opinions if it worth to use it instead.
> 

I've looked into MFD modeling, but it would only make sense if we break
up the exar driver, change its xr17v35x part into a platform device and
create a dual-cell MFD for the PCI device. I don't think that would be
beneficial here. There are also dependencies between the UART part and
the MPIOs, specifically during init. All that would create a lot of
churn to the existing exar code.

I'm now passing the parent reference via device.parent instead of using
platform data.

Jan

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