From: Jonathan Cameron <jic23@cam.ac.uk>
To: Manuel Stahl <manuel.stahl@iis.fraunhofer.de>
Cc: linux-iio@vger.kernel.org
Subject: Re: cs_change for SPI transfers
Date: Tue, 11 Jan 2011 19:03:49 +0000 [thread overview]
Message-ID: <4D2CA995.80002@cam.ac.uk> (raw)
In-Reply-To: <4D2B1619.1010408@iis.fraunhofer.de>
On 01/10/11 14:22, Manuel Stahl wrote:
> Hi,
>
> I think there's an error in most IIO devices that use SPI transfers.
>
> Haavard Skinnemoen wrote:
>> The normal behaviour is:
>> * After all transfers except the last: CS stays active
>> * After the last transfer: CS goes inactive
>>
>> The cs_change flag is used to invert this behaviour. So for the last
>> transfer, cs_change indicates that CS should stay active after the
>> transfer (though the driver may not actually be able to do so, e.g. if
>> the message is followed by a message to a different device.)
>>
>
> The drivers in IIO set cs_change for all transfers (including the
> last in a message), which is not what we want. I can prepare a patch
> to correct this.
Yikes.
They win for completely counter intuitive interface... I guess I can see why
they did it like that (to make 0 the default behaviour).
Clearer naming would have been nice. cs_change_non_default or something...
Please do submit a patch set for this.
Jonathan
prev parent reply other threads:[~2011-01-11 18:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-10 14:22 cs_change for SPI transfers Manuel Stahl
2011-01-11 19:03 ` Jonathan Cameron [this message]
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