Message-ID: <48F8E019.20600@mimc.co.uk>
Date: Fri, 17 Oct 2008 19:57:29 +0100
From: Mark Jackson <mpfj@mimc.co.uk>
Organization: Mercury IMC Ltd
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To: David Brownell <david-b@pacbell.net>
CC: Alessandro Zummo <alessandro.zummo@towertech.it>,
       rtc-linux@googlegroups.com, lkml <linux-kernel@vger.kernel.org>,
       spi-devel-general@lists.sourceforge.net
Subject: Re: [PATCH] Add Dallas DS1390 RTC chip
References: <48F452BE.2030901@mimc.co.uk> <20081014101703.1ded0259@i1501.lan.towertech.it> <48F8467C.5010902@mimc.co.uk> <200810170829.06699.david-b@pacbell.net>
In-Reply-To: <200810170829.06699.david-b@pacbell.net>
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David Brownell wrote:
> On Friday 17 October 2008, Mark Jackson wrote:
>>>> +    /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
>>>> +    xfer.tx_buf = chip->tx_buf;
>>>> +    xfer.rx_buf = chip->rx_buf;
>>>  you use the same buffer a few functions below. either
>>>  one way or the other. please investigate with the spi subsystem maintainer.
>> David,
>>
>> Just to double check (as per Alessandro's suggestion), is this okay use of the 
>> spi buffers ?
> 
> Yes.  That comment deserves to be updated.
> 
> SPI does bi-directional I/O, and the underlying controller
> should be able to just replace the contents of a buffer
> with a spi_transfer that uses the same rx and tx buffers.

Excellent.  Thanks for the confirmation.

Regards
Mark
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