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From: Wolfram Sang <wsa@the-dreams.de>
To: Ray Jui <ray.jui@broadcom.com>
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: Wed, 4 Sep 2019 23:37:45 +0200	[thread overview]
Message-ID: <20190904213745.GG23608@ninjato> (raw)
In-Reply-To: <540c4e2d-0dd5-5260-30b2-e1589b279d71@broadcom.com>

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> 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.

Well, given that you add new quirks in the original patch here, you are
kind of breaking it already. Most transfers which are not SMBus-alike
transfers would now be rejected. For SMBus-alike transfers which are
sent via I2C_RDWR (which is ugly), I have to think about it.

> 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?

I don't think so. If you check regmap_get_i2c_bus() then it checks the
adapter functionality and chooses the best transfer option then. I may
be missing something but I would wonder if the sound system does
something special and different.


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WARNING: multiple messages have this Message-ID (diff)
From: Wolfram Sang <wsa@the-dreams.de>
To: Ray Jui <ray.jui@broadcom.com>
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: Wed, 4 Sep 2019 23:37:45 +0200	[thread overview]
Message-ID: <20190904213745.GG23608@ninjato> (raw)
In-Reply-To: <540c4e2d-0dd5-5260-30b2-e1589b279d71@broadcom.com>


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> 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.

Well, given that you add new quirks in the original patch here, you are
kind of breaking it already. Most transfers which are not SMBus-alike
transfers would now be rejected. For SMBus-alike transfers which are
sent via I2C_RDWR (which is ugly), I have to think about it.

> 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?

I don't think so. If you check regmap_get_i2c_bus() then it checks the
adapter functionality and chooses the best transfer option then. I may
be missing something but I would wonder if the sound system does
something special and different.


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

  reply	other threads:[~2019-09-04 21:37 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
2019-09-03 23:11         ` Ray Jui
2019-09-04 21:37         ` Wolfram Sang [this message]
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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