On 10/04/2011 06:55 PM, Grant Likely : > On Tue, Oct 04, 2011 at 08:08:27AM -0500, Rob Herring wrote: >> Nicolas, >> >> On 10/04/2011 03:18 AM, Nicolas Ferre wrote: >>> On 10/04/2011 03:58 AM, Rob Herring : >>>> On 10/03/2011 04:51 AM, Nicolas Ferre wrote: >>>>> +Optional properties: >>>>> +- atmel,use-dma-rx: use of PDC or DMA for receiving data >>>>> +- atmel,use-dma-tx: use of PDC or DMA for transmitting data >>>> >>>> Is this an internal DMA or separate DMA controller? If the latter, these >>>> should be phandles to a DMA channel/request. >>> >>> Well, for now it relies on PDC (looks like an internal DMA). There is no >>> notion of channel/request so I think it is appropriate to keep it like this. >>> >> >> Okay. Although, this is a bit of Linux creeping into DT. DT should >> describe the h/w. You should really be describing whether the h/w >> supports DMA or not rather than whether you want to use DMA or not. >> Since DMA support is really tied to the SOC rather than board, you could >> just use the compatible string to distinguish platforms that support DMA >> or not. So what is determining this setting? Is it purely user choice? > > It is okay for a binding to still requires config properties like this > to state if the DMA can be used, even if compatible is enough to > distinquish. However, you're right to bring it up. It is a design > choice that should be made thoughtfully. Grant, Rob, Thanks for your inputs. I would like to keep this binding to allow the user to choose the way he likes to use integrated DMA. I plan to resend a patch series about this serial driver once I will be able to propose a rs485 binding. Cheers, -- Nicolas Ferre -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
