Re: [RFC PATCH] dma: at_xdmac: creation of the atmel eXtended DMA Controller driver

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

 




On Tue, Jun 10, 2014 at 09:15:14PM +0200, Arnd Bergmann wrote:
> On Tue, May 27, 2014 at 10:35:36AM +0200, Ludovic Desroches wrote:
> > +static struct dma_chan *at_xdmac_xlate(struct of_phandle_args *dma_spec,
> > +                                    struct of_dma *of_dma)
> > +{
> > +     struct at_xdmac_chan    *atchan;
> > +     struct dma_chan         *chan;
> > +     dma_cap_mask_t          mask;
> > +     struct platform_device  *pdev = of_find_device_by_node(dma_spec->np);
> 
> No need to search through all the device nodes, you can look up the
> device from of_dma->of_dma_data.

Thanks for the tip.

> 
> > +     if (dma_spec->args_count != 2) {
> > +             dev_err(&pdev->dev, "dma phandler args: bad number of args\n");
> > +             return NULL;
> > +     }
> > +
> > +     dma_cap_zero(mask);
> > +     dma_cap_set(DMA_SLAVE, mask);
> > +     chan = dma_request_channel(mask, NULL, NULL);
> > +     if (!chan) {
> > +             dev_err(&pdev->dev, "can't get a dma channel\n");
> > +             return NULL;
> > +     }
> 
> You must use dma_get_any_slave_channel. dma_request_channel gives you a
> channel from a random dma engine that is present in the system, not
> necessarily the one you are managing here.

It is planned to use dma_get_any_slave_channel but currently I am doing
tests on a 3.10 kernel that's why I am still using dma_request_channel.

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




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux