linux-kernel - Re: [PATCH RESEND] i2c: tegra: Add SMBus block read function

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Date:   Wed, 16 Feb 2022 21:50:36 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Akhil R <akhilrajeev@...dia.com>,
        "christian.koenig@....com" <christian.koenig@....com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        Mikko Perttunen <mperttunen@...dia.com>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "sumit.semwal@...aro.org" <sumit.semwal@...aro.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Svyatoslav Ryhel <clamor95@...il.com>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Krishna Yarlagadda <kyarlagadda@...dia.com>
Subject: Re: [PATCH RESEND] i2c: tegra: Add SMBus block read function

16.02.2022 06:54, Akhil R пишет:
>> 14.02.2022 07:49, Akhil R пишет:
>>>> It's unclear to me what's the point of emulating
>>>> I2C_FUNC_SMBUS_READ_BLOCK_DATA within the driver if you could use
>>>> i2c_smbus_read_i2c_block_data().
>>> We are looking to support I2C_M_RECV_LEN where the length is read from
>>> the first byte of data. I see that i2c_smbus_read_i2c_block_data()
>>> requires the length to be passed from the client driver.
>>>
>>> BTW, I2C_FUNC_SMBUS_WRITE_BLOCK_DATA is also expected to be
>> supported.
>>> It is included in I2C_FUNC_SMBUS_EMUL. I suppose, it doesn't require
>>> any additional change in the driver. The client driver should populate
>>> the first byte as the length of data to be transferred.
>>
>> Please support both read and write.
> Both read and write are supported. Write doesn't require any additional
> change in the driver as far as I understand.
> 
> It is actually the same that I mentioned before. Or am I missing something here?

I missed that I2C_FUNC_SMBUS_EMUL includes I2C_FUNC_SMBUS_WRITE_BLOCK_DATA.