Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v1 00/12] Improvements for Tegra I2C driver
To:     =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= <mirq-linux@rere.qmqm.pl>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Laxman Dewangan <ldewangan@nvidia.com>,
        Wolfram Sang <wsa@the-dreams.de>, linux-i2c@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20200831202303.15391-1-digetx@gmail.com>
 <20200902212026.GD1624@qmqm.qmqm.pl>
 <04aae642-80f9-d22e-1d80-bb206bb27a8b@gmail.com>
 <20200903164709.GA7406@qmqm.qmqm.pl>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <e1b7a9fc-e638-8576-a79e-7c2cf1cfbfe2@gmail.com>
Date:   Fri, 4 Sep 2020 01:18:15 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20200903164709.GA7406@qmqm.qmqm.pl>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

03.09.2020 19:47, Michał Mirosław пишет:
> On Thu, Sep 03, 2020 at 04:12:13AM +0300, Dmitry Osipenko wrote:
>> 03.09.2020 00:20, Michał Mirosław пишет:
>>> BTW, I wonder if you could expose i2c_in_atomic_xfer_mode() and use it
>>> to differentiate atomic_xfer from normal and get rid of the internal
>>> flag and .master_xfer_atomic callback.
>>
>> The atomic transfer uses 90% of the code path that a non-atomic transfer
>> uses. I don't see how it could be exposed without duplicated lots of the
>> code, unless I'm not missing what you're suggesting.
> 
> The I2C core falls back to .master_xfer even in atomic mode if
> .master_xfer_atomic is NULL, so what I'm suggesting is to make
> i2c_in_atomic_xfer_mode() public (from i2c-core.h) and use it in
> normal .master_xfer to choose atomic wait variants.

Okay, I see now. But the I2C core prints a noisy warning if
master_xfer_atomic is NULL in atomic transfer, so I'm not sure whether
changing all that code will bring much benefits to us and anyone else.
It's a bit too questionable change to me, but maybe I'm still missing
something. Will be great if you could provide an example patch.