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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Sergey.Semin@baikalelectronics.ru
Cc: Serge Semin <fancer.lancer@gmail.com>,
	Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
	Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru>,
	Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
	Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>,
	Ekaterina Skachko <Ekaterina.Skachko@baikalelectronics.ru>,
	Vadim Vlasov <V.Vlasov@baikalelectronics.ru>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Burton <paulburton@kernel.org>,
	Ralf Baechle <ralf@linux-mips.org>,
	Jarkko Nikula <jarkko.nikula@linux.intel.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] i2c: designeware: Add Baikal-T1 SoC DW I2C specifics support
Date: Fri, 6 Mar 2020 15:54:45 +0200
Message-ID: <20200306135445.GE1748204@smile.fi.intel.com> (raw)
In-Reply-To: <20200306132001.1B875803087C@mail.baikalelectronics.ru>

First of all, I got only 3 out of 6 patches. Are you sure you properly prepared
the series?

On Fri, Mar 06, 2020 at 04:19:49PM +0300, Sergey.Semin@baikalelectronics.ru wrote:
> From: Serge Semin <fancer.lancer@gmail.com>

Same comment as per DMA series, try next time to link the cover letter to the
series correctly.

> There are three DW I2C controllers embedded into the Baikal-T1 SoC. Two
> of them are normal with standard DW I2C IP-core configurations and registers
> accessible over normal MMIO space - so they are acceptable by the available
> DW I2C driver with no modification.

> But there is a third, which is a bit
> different. Its registers are indirectly accessed be means of "command/data
> in/data out" registers tuple. In order to have it also supported by the DW
> I2C driver, we must modify the code a bit. This is a main purpose of this
> patchset.
> 
> First of all traditionally we replaced the legacy plain text-based dt-binding
> file with yaml-based one. Then we found and fixed a bug in the DW I2C FIFO size
> detection algorithm which tried to do it too early before dw_readl/dw_writel
> methods could be used.

So far so good (looks like, I think colleagues of mine and myself will review
individual patches later on).

> Finally we introduced a platform-specific flag
> ACCESS_INDIRECT, which would enable the indirect access to the DW I2C registers
> implemented for one of the Baikal-T1 SoC DW I2C controllers. See the commit
> message of the corresponding patch for details.

This is quite questionable. In Intel SoCs we have indirect I²C controllers to
access (inside PMIC, for example). The approach used to do that is usually to
have an IPC mechanism and specific bus controller driver. See i2c-cht-wc.c for
instance.

I'm not sure if it makes a lot of duplication and if actually switching I²C
DesignWare driver to regmap API will solve it. At least that is the second
approach I would consider.

But I'll wait others to comment on this. We have to settle the solution before
going further.

> This patchset is rebased and tested on the mainline Linux kernel 5.6-rc4:
> commit 98d54f81e36b ("Linux 5.6-rc4").

`git format-patch --base ...` should do the job.

> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>

Same comment as per UART patch. Who is the Alexey in relation to the work done?

-- 
With Best Regards,
Andy Shevchenko

  reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06 13:19 Sergey.Semin-UN2wsyeM1qLJ45LvJ/SUn8gurn75+9Lz
2020-03-06 13:54 ` Andy Shevchenko [this message]
     [not found] ` <20200306135451.4AF0480307C4@mail.baikalelectronics.ru>
2020-03-31 11:48   ` Sergey Semin
2020-03-31 14:25     ` Andy Shevchenko
     [not found]       ` <20200331142530.GM1922688-XvqNBM/wLWRrdx17CPfAsdBPR1lH4CV8@public.gmane.org>
2020-03-31 16:28         ` Sergey Semin
2020-03-31 17:17           ` Andy Shevchenko
2020-03-31 19:14             ` Sergey Semin
2020-05-10  9:50 ` [PATCH v2 00/12] i2c: designeware: Add Baikal-T1 System I2C support Serge Semin
2020-05-10  9:50   ` [PATCH v2 01/12] scripts/dtc: check: Add 10bit/slave i2c reg flags support Serge Semin
2020-05-10  9:50   ` [PATCH v2 02/12] dt-bindings: i2c: Convert DW I2C binding to DT schema Serge Semin
2020-05-11 16:09     ` Rob Herring
2020-05-11 19:50       ` Serge Semin
2020-05-10  9:50   ` [PATCH v2 03/12] dt-bindings: i2c: dw: Add Baikal-T1 SoC I2C controller Serge Semin
2020-05-18 20:33     ` Rob Herring
2020-05-18 21:39       ` Serge Semin
2020-05-10  9:50   ` [PATCH v2 04/12] i2c: designware: Convert driver to using regmap API Serge Semin
2020-05-20 12:16     ` Jarkko Nikula
2020-05-21  2:02       ` Serge Semin
2020-05-10  9:50   ` [PATCH v2 05/12] i2c: designware: Use `-y` to build multi-object modules Serge Semin
2020-05-20 12:16     ` Jarkko Nikula
2020-05-10  9:50   ` [PATCH v2 06/12] i2c: designware: slave: Set DW I2C core module dependency Serge Semin
2020-05-20 12:15     ` Jarkko Nikula
2020-05-10  9:50   ` [PATCH v2 07/12] i2c: designware: Move Baytrail sem config to the platform if-clause Serge Semin
2020-05-20 12:16     ` Jarkko Nikula
2020-05-21  2:22       ` Serge Semin
2020-05-25 13:01         ` Jarkko Nikula
2020-05-26 18:40           ` Serge Semin
2020-05-10  9:50   ` [PATCH v2 08/12] i2c: designware: Introduce platform drivers glue layer interface Serge Semin
2020-05-20 12:46     ` Jarkko Nikula
2020-05-21  2:37       ` Serge Semin
2020-05-25 13:16         ` Jarkko Nikula
2020-05-25 13:42           ` Andy Shevchenko
2020-05-26 20:38           ` Serge Semin
2020-05-10  9:50   ` [PATCH v2 09/12] i2c: designware: Unpin Microsemi Ocelot I2C into a glue driver Serge Semin
2020-05-10  9:50   ` [PATCH v2 10/12] i2c: designware: Discard Cherry Trail model flag Serge Semin
2020-05-20 12:17     ` Jarkko Nikula
2020-05-10  9:50   ` [PATCH v2 11/12] i2c: designware: Use provided regmap instead of reg resource Serge Semin
2020-05-10  9:50   ` [PATCH v2 12/12] i2c: designware: Add Baikal-T1 System I2C glue driver Serge Semin

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