Message-ID: <5038F50E.7030807@gmail.com>
Date: Sat, 25 Aug 2012 17:53:50 +0200
From: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
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To: Stephen Warren <swarren@wwwdotorg.org>
CC: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        Grant Likely <grant.likely@secretlab.ca>,
        Rob Herring <rob.herring@calxeda.com>, Rob Landley <rob@landley.net>,
        Russell King <linux@arm.linux.org.uk>,
        Lior Amsalem <alior@marvell.com>, Andrew Lunn <andrew@lunn.ch>,
        Gregory CLEMENT <gregory.clement@free-electrons.com>,
        Ben Dooks <ben.dooks@codethink.co.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/9] pinctrl: mvebu: pinctrl driver core
References: <1344689809-6223-1-git-send-email-sebastian.hesselbarth@gmail.com> <1345623750-10645-1-git-send-email-sebastian.hesselbarth@gmail.com> <1345623750-10645-2-git-send-email-sebastian.hesselbarth@gmail.com> <5035445B.6000500@wwwdotorg.org> <CABJ1b_Tdr80DGqb-FRzwDbF3m7g6fBguk5GtRAfRUYx5Sqy_cA@mail.gmail.com> <50366E44.4030606@wwwdotorg.org> <50369305.6050304@gmail.com> <50369FEE.8000003@wwwdotorg.org> <5036B639.20608@gmail.com> <5036F651.4020700@wwwdotorg.org>
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On 08/24/2012 05:34 AM, Stephen Warren wrote:
> On 08/23/2012 05:01 PM, Sebastian Hesselbarth wrote:
>> So possible, valid combinations for uart1 would be:
>> (a) mpp_uart1;
>> (b) mpp_uart1, mpp2, mpp3;
>> (c) mpp_uart1, mpp21, mpp22;
>> (d) mpp_uart1, mpp2, mpp22;
>> (e) mpp_uart1, mpp21, mpp3;
>>  [...]
> In the example above, there is a single function named "uart1". If this
> was all the HW supported, I'd expect the driver's
> pinmux_ops.get_functions_count() to return 1,
> pinmux_ops.get_function_name(0) to return "uart1", and
> pinmux_ops.get_function_name(n>0) to return an error.
>
> In practice, I assume there are many other options that can be muxed
> onto mpp2/3/21/22/uart1, so they'd be included in the list as well.
>
> I don't expect any scanning, no. I'd expect that tables provided by the
> SoC-specific drivers to be:
>
> * A table of pins
> * A table of groups
> * A table of functions
>
> No scanning involved.

Stephen,

now I do understand but in the current driver we pass pingroups associated
with the available functions, i.e. "mpp2" with "uart1", "uart2", "sdio0", aso.
IMHO for the above three functions it would be better to have functions associated
with the corresponding groups, i.e. "uart1" with "mpp_uart1", "mpp2", "mpp3", aso.

That would require some larger rework of the driver and therefore I just
wanted to make sure, that I hit your expectations/explanations.

Sebastian
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