Re: [PATCH] usb: chipidea: Configure DMA properties and ops from DT

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Mar 18, 2016 at 09:54:14AM +0800, Peter Chen wrote:
> Although I don't know what kinds of bugs it may have, it may be
> met before, otherwise, why most of platform drivers need to call
> dma_set_coherent_mask or dma_coerce_mask_and_coherent explicitly

See Documentation/DMA-API.txt, specifically the section starting

  Part Ic - DMA addressing limitations
  ------------------------------------

and also Documentation/DMA-API-HOWTO.txt, the section on

  DMA addressing limitations

which provides further information.

Drivers using DMA should be using dma_set_mask_and_coherent() _or_
one of dma_set_mask() and dma_set_coherent_mask() depending on which
types of DMA they wish to perform.  Drivers should not use
dma_coerce_mask_and_coherent() except in exceptional circumstances:
that function is more a marker that they or some bus/platform code
is doing something wrong.

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux