linux-kernel - Re: [PATCH v8 2/3] i2c: iproc: Add Broadcom iProc I2C Driver

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Message-ID: <54D7A694.4000903@broadcom.com>
Date:	Sun, 8 Feb 2015 10:10:28 -0800
From:	Ray Jui <rjui@...adcom.com>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Arend van Spriel <arend@...adcom.com>,
	Kevin Cernekee <cernekee@...omium.org>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"Grant Likely" <grant.likely@...aro.org>,
	Christian Daudt <bcm@...thebug.org>,
	Matt Porter <mporter@...aro.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Scott Branden <sbranden@...adcom.com>,
	Dmitry Torokhov <dtor@...gle.com>, <linux-i2c@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<bcm-kernel-feedback-list@...adcom.com>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH v8 2/3] i2c: iproc: Add Broadcom iProc I2C Driver



On 2/8/2015 3:03 AM, Wolfram Sang wrote:
> 
>>> Is it really a HW limitation? Could the driver later be extended to
>>> continue filling the FIFO if a certain threshold is reached?
>>>
>>
>> Will return -EOPNOTSUPP. This really depends on whether or not we expect
>> one sequence of START + SLV ADDR + DATA + STOP per i2c message. I can
>> later extend the driver to refill/re-drain the FIFO for data size >= 64
>> bytes, if one sequence of SATRT...STOP per message is not a requirement.
> 
> It is important to have the terminology clear here: One transfer can
> consist of multiple messages. The transfer uses START/STOP at the
> beginning/end, the messages within the transfer only REPEATED_START.
> 
Okay. Let me check with our ASIC engineer to see if there's a way to get
the driver extended to support the case when data size is larger than
the FIFO size. From my understanding based on the data sheet I have, I
don't think that can be done with this controller. But if the ASIC
engineers tells me the opposite, I'll add it as a separate patch later.

Thanks,

Ray

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