From: Varun Wadekar <vwadekar-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
To: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Subject: Re: Forcing PIO mode instead of DMA via DT property
Date: Mon, 23 Jul 2012 09:19:57 +0530 [thread overview]
Message-ID: <500CC9E5.4060109@nvidia.com> (raw)
In-Reply-To: <201207230531.02305.marex-ynQEQJNshbs@public.gmane.org>
>> One option would be to
>> put a compile time flag in the driver, which prefers PIO than DMA. I
>> believe by default DMA is the first preference.
> Certainly, but please consider you might want to use PIO only on selected
> instances of the driver (aka. selected busses, I wasn't probably clear enough,
> this is a bus driver), not degrade performance on all of them. Possibly due to a
> specific hardware wiring of the particular system.
>
Device Trees are a replacement for board files. If your board uses PIO
mode due to some hardware limitations, then you need to specify this in
the .dt for that board. The driver should then just query this property
and proceed with its init.
Regards,
Varun
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next prev parent reply other threads:[~2012-07-23 3:49 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-22 21:28 Forcing PIO mode instead of DMA via DT property Marek Vasut
[not found] ` <201207222328.27008.marex-ynQEQJNshbs@public.gmane.org>
2012-07-23 3:25 ` Aggrwal Poonam-B10812
[not found] ` <ACB6D0C0104CFF42A45A5D82A0DD4F3D079B4DAE-RL0Hj/+nBVDYdknt8GnhQq4g8xLGJsHaLnY5E4hWTkheoWH0uzbU5w@public.gmane.org>
2012-07-23 3:31 ` Marek Vasut
[not found] ` <201207230531.02305.marex-ynQEQJNshbs@public.gmane.org>
2012-07-23 3:49 ` Varun Wadekar [this message]
2012-07-23 4:38 ` Aggrwal Poonam-B10812
2012-07-23 5:47 ` Wolfgang Denk
[not found] ` <20120723054758.C622C200263-C2Gvrrd9BC/j/ljBK/0BTg@public.gmane.org>
2012-07-24 1:56 ` Aggrwal Poonam-B10812
[not found] ` <ACB6D0C0104CFF42A45A5D82A0DD4F3D079B6B36-RL0Hj/+nBVDYdknt8GnhQq4g8xLGJsHaLnY5E4hWTkheoWH0uzbU5w@public.gmane.org>
2012-07-24 4:17 ` Marek Vasut
[not found] ` <201207240617.31565.marex-ynQEQJNshbs@public.gmane.org>
2012-07-24 14:49 ` Aggrwal Poonam-B10812
[not found] ` <ACB6D0C0104CFF42A45A5D82A0DD4F3D079B7AA7-RL0Hj/+nBVDYdknt8GnhQq4g8xLGJsHaLnY5E4hWTkheoWH0uzbU5w@public.gmane.org>
2012-07-30 14:00 ` Marek Vasut
2012-07-24 13:19 ` Arnd Bergmann
[not found] ` <201207241319.45101.arnd-r2nGTMty4D4@public.gmane.org>
2012-07-24 14:35 ` Wolfgang Denk
[not found] ` <20120724143533.080F5200247-C2Gvrrd9BC/j/ljBK/0BTg@public.gmane.org>
2012-07-24 14:55 ` Mitch Bradley
[not found] ` <500EB77B.6050105-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>
2012-07-24 14:59 ` Mis-wrapped text Mitch Bradley
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