RE: Forcing PIO mode instead of DMA via DT property
From: Aggrwal Poonam-B10812 <hidden>
Date: 2012-07-23 03:25:35
-----Original Message----- From: devicetree-discuss [mailto:devicetree-discuss- bounces+poonam.aggrwal=freescale.com-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org] On Behalf Of Marek Vasut Sent: Monday, July 23, 2012 2:58 AM To: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Cc: pavel-ynQEQJNshbs@public.gmane.org; Wolfgang Denk Subject: Forcing PIO mode instead of DMA via DT property Hi guys, I'm trying to implement a driver that can do both DMA and PIO, and it would be nice if the user was able to select the mode (on a per-bus basis) using the DT. The PIO mode can reduce the overhead in some cases and therefore be better choice than the DMA (for example when most transfers move only very few data, or when board-specific hardware properties kick in). I was thinking about using some "manf,use-pio" DT property, but I haven't found any such example yet, so I wonder if this is a good idea.
Not sure, but as far as I understand device tree is to publish the hardware capabilities, not the user choice/configuration. 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. Regards Poonam
What is your suggestion how I shoud address such a problem? Thanks in advance! Best regards, Marek Vasut _______________________________________________ devicetree-discuss mailing list devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org https://lists.ozlabs.org/listinfo/devicetree-discuss