On Mon, Oct 27, 2014 at 11:59:42PM +0000, Russell King - ARM Linux wrote: > On Tue, Oct 28, 2014 at 12:44:31AM +0100, Piotr Król wrote: > > Hi all, > > according to BCM2835 ARM Peripherals spec DMA is optional functionality > > for ARM PL011 UART and it is not supported on this SoC. It looks like > > amba-pl011 search for device tree property (dma-names) unconditionally, > > what leads to error message: > > > > of_dma_request_slave_channel: dma-names property of node '/soc/uart@7e201000' missing or empty > > uart-pl011 20201000.uart: no DMA platform data > > > > I assume that if it is possible that amba-pl011 can be without DMA we > > should check if DMA is supported and then try to read properties. Is > > there any known method for checking dma support ? If yes that I would be > > glad for any pointers. > > > > Let me know if I should ignore/accept this error message or there is > > some code fix needed. > > A great many implementations of PL011 do not have DMA support (some have > DMA support but its well broken.) The driver has always supported PIO > mode, and continues to do so. > Driver works fine but IMHO this error message confuse user. Should I assume that error message is expected and we should not avoid it by trying to check if DMA is supported ? BTW above error message do not indicate that DMA is not supported but indicates that something is wrong with DT, what in this case is not true. Thanks, Piotr Król -- 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
