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From: Ray Jui <ray.jui@broadcom.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	bcm-kernel-feedback-list@broadcom.com,
	Florian Fainelli <f.fainelli@gmail.com>,
	Lori Hikichi <lori.hikichi@broadcom.com>,
	Icarus Chau <icarus.chau@broadcom.com>,
	Shivaraj Shetty <sshetty1@broadcom.com>
Subject: Re: [PATCH v1 1/1] i2c: iproc: Add i2c repeated start capability
Date: Tue, 3 Sep 2019 16:11:16 -0700	[thread overview]
Message-ID: <540c4e2d-0dd5-5260-30b2-e1589b279d71@broadcom.com> (raw)
In-Reply-To: <20190831094940.GA1138@kunai>



On 8/31/19 2:49 AM, Wolfram Sang wrote:
> Hi Ray,
> 
>>> With all the limitations in place, I wonder if it might be easier to
>>> implement an smbus_xfer callback instead? What is left that makes this
>>> controller more than SMBus and real I2C?
>>>
>>
>> Right. But what is the implication of using smbus_xfer instead of
>> master_xfer in our driver?
>>
>> Does it mean it will break existing functions of the i2c app that our
>> customers developed based on i2cdev (e.g., I2C_RDWR)?
> 
> If the customers uses I2C_RDWR (and it cannot be mapped to i2c_smbus_*
> calls) then this is an indication that there is some I2C functionality
> left which the HW can provide. I'd be interested which one, though.
> 
>>
>> 1) Does
> 
> Maybe you wanted to describe it here and it got accidently cut off? >

I think you are right that the controller does not seem to support 
additional I2C features in addition to SMBUS.

However, my concern of switching to the smbus_xfer API is:

1) Some customers might have used I2C_RDWR based API from i2cdev. 
Changing from master_xfer to smbus_xfer may break the existing 
applications that are already developed.

2) The sound subsystem I2C regmap based implementation seems to be using 
i2c_ based API instead of smbus_ based API. Does this mean this will 
also break most of the audio codec drivers with I2C regmap API based usage?

Thanks,

Ray

> Regards,
> 
>     Wolfram
> 

WARNING: multiple messages have this Message-ID (diff)
From: Ray Jui <ray.jui@broadcom.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org,
	Lori Hikichi <lori.hikichi@broadcom.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Shivaraj Shetty <sshetty1@broadcom.com>,
	Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>,
	linux-kernel@vger.kernel.org,
	Icarus Chau <icarus.chau@broadcom.com>,
	Rob Herring <robh+dt@kernel.org>,
	bcm-kernel-feedback-list@broadcom.com, linux-i2c@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 1/1] i2c: iproc: Add i2c repeated start capability
Date: Tue, 3 Sep 2019 16:11:16 -0700	[thread overview]
Message-ID: <540c4e2d-0dd5-5260-30b2-e1589b279d71@broadcom.com> (raw)
In-Reply-To: <20190831094940.GA1138@kunai>



On 8/31/19 2:49 AM, Wolfram Sang wrote:
> Hi Ray,
> 
>>> With all the limitations in place, I wonder if it might be easier to
>>> implement an smbus_xfer callback instead? What is left that makes this
>>> controller more than SMBus and real I2C?
>>>
>>
>> Right. But what is the implication of using smbus_xfer instead of
>> master_xfer in our driver?
>>
>> Does it mean it will break existing functions of the i2c app that our
>> customers developed based on i2cdev (e.g., I2C_RDWR)?
> 
> If the customers uses I2C_RDWR (and it cannot be mapped to i2c_smbus_*
> calls) then this is an indication that there is some I2C functionality
> left which the HW can provide. I'd be interested which one, though.
> 
>>
>> 1) Does
> 
> Maybe you wanted to describe it here and it got accidently cut off? >

I think you are right that the controller does not seem to support 
additional I2C features in addition to SMBUS.

However, my concern of switching to the smbus_xfer API is:

1) Some customers might have used I2C_RDWR based API from i2cdev. 
Changing from master_xfer to smbus_xfer may break the existing 
applications that are already developed.

2) The sound subsystem I2C regmap based implementation seems to be using 
i2c_ based API instead of smbus_ based API. Does this mean this will 
also break most of the audio codec drivers with I2C regmap API based usage?

Thanks,

Ray

> Regards,
> 
>     Wolfram
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-09-03 23:11 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-07  4:09 [PATCH v1 1/1] i2c: iproc: Add i2c repeated start capability Rayagonda Kokatanur
2019-08-07  4:09 ` Rayagonda Kokatanur
2019-08-07  4:09 ` Rayagonda Kokatanur
2019-08-12 17:33 ` Ray Jui
2019-08-12 17:33   ` Ray Jui
2019-08-29 20:41   ` Wolfram Sang
2019-08-29 20:41     ` Wolfram Sang
2019-08-30 12:56 ` Wolfram Sang
2019-08-30 12:56   ` Wolfram Sang
2019-08-30 18:35   ` Ray Jui
2019-08-30 18:35     ` Ray Jui
2019-08-31  9:49     ` Wolfram Sang
2019-08-31  9:49       ` Wolfram Sang
2019-09-03 23:11       ` Ray Jui [this message]
2019-09-03 23:11         ` Ray Jui
2019-09-04 21:37         ` Wolfram Sang
2019-09-04 21:37           ` Wolfram Sang
2019-09-24 17:23           ` Ray Jui
2019-09-24 17:23             ` Ray Jui
2019-09-24 18:57             ` Wolfram Sang
2019-09-24 18:57               ` Wolfram Sang
2019-09-24 22:23               ` Ray Jui
2019-09-24 22:23                 ` Ray Jui

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