Re: [PATCH 2/5] i2c: sh_mobile: add DMA support

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

 



On Thursday 11 December 2014 08:37:27 Wolfram Sang wrote:
> > I think this is a limitation of driver may not be for HW. The right model
> > for dma_chan is to be viewed as SW channels and not the ones of HW (yes
> > that is how most of the drivers use that, but we can improve upon)
> > 
> > If we rework the driver to view dma_chan as SW channels, then you can
> > accept multiple channel requests and accept based on if we are able link
> > the channel to that peripheral or not.
> 
> In my understanding, the DMA driver does exactly that.

Actually it doesn't at the moment, I should implement that.

> However, it is not even loaded at the time the I2C driver wants a channel,
> so the dmaengine core defers the probe. That is the problem for optional DMA
> channels: we can't know when deferring probe won't help anymore and don't
> know when it is time to fall back to PIO.

This is true regardless of the whether the driver exposes HW or SW channels.

-- 
Regards,

Laurent Pinchart

--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Linux ARM (vger)]     [Linux ARM MSM]     [Linux Omap]     [Linux Arm]     [Linux Tegra]     [Fedora ARM]     [Linux for Samsung SOC]     [eCos]     [Linux PCI]     [Linux Fastboot]     [Gcc Help]     [Git]     [DCCP]     [IETF Announce]     [Security]     [Linux MIPS]     [Yosemite Campsites]

  Powered by Linux