linux-kernel - Re: [PATCH v2 04/12] i2c: designware: Convert driver to using regmap API

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Date:   Wed, 20 May 2020 15:16:07 +0300
From:   Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, linux-mips@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Jean Delvare <jdelvare@...e.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Max Staudt <max@...as.org>, Stefan Roese <sr@...x.de>,
        Uwe Kleine-König <uwe@...ine-koenig.org>,
        Shaokun Zhang <zhangshaokun@...ilicon.com>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/12] i2c: designware: Convert driver to using regmap
 API

On 5/10/20 12:50 PM, Serge Semin wrote:
> Seeing the DW I2C driver is using flags-based accessors with two
> conditional clauses it would be better to replace them with the regmap
> API IO methods and to initialize the regmap object with read/write
> callbacks specific to the controller registers map implementation. This
> will be also handy for the drivers with non-standard registers mapping
> (like an embedded into the Baikal-T1 System Controller DW I2C block, which
> glue-driver is a part of this series).
> 
> As before the driver tries to detect the mapping setup at probe stage and
> creates a regmap object accordingly, which will be used by the rest of the
> code to correctly access the controller registers. In two places it was
> appropriate to convert the hand-written read-modify-write and
> read-poll-loop design patterns to the corresponding regmap API
> ready-to-use methods.
> 
> Note the regmap IO methods return value is checked only at the probe
> stage. The rest of the code won't do this because basically we have
> MMIO-based regmap so non of the read/write methods can fail (this also
> won't be needed for the Baikal-T1-specific I2C controller).
> 
> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: Paul Burton <paulburton@...nel.org>
> Cc: Ralf Baechle <ralf@...ux-mips.org>
> Cc: Wolfram Sang <wsa@...-dreams.de>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Frank Rowand <frowand.list@...il.com>
> Cc: devicetree@...r.kernel.org
> Cc: linux-mips@...r.kernel.org
> ---
>   drivers/i2c/busses/Kconfig                 |   1 +
>   drivers/i2c/busses/i2c-designware-common.c | 171 +++++++++++++++------
>   drivers/i2c/busses/i2c-designware-core.h   |  18 +--
>   drivers/i2c/busses/i2c-designware-master.c | 125 ++++++++-------
>   drivers/i2c/busses/i2c-designware-slave.c  |  77 +++++-----
>   5 files changed, 239 insertions(+), 153 deletions(-)
> 
Looking at patches 4/12-12/12 I think it would be good to move fixes and 
less invasive patches before this. Like

i2c: designware: slave: Set DW I2C core module dependency
i2c: designware: Use `-y` to build multi-object modules
i2c: designware: Move Baytrail sem config to the platform if-clause

That said, you may add:

Tested-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>