On Wed, Nov 05, 2014 at 05:30:51PM +0100, Sebastian Andrzej Siewior wrote: > On 11/05/2014 05:20 PM, Lennart Sorensen wrote: > > On Wed, Nov 05, 2014 at 10:33:15AM -0500, Lennart Sorensen wrote: > >> Two systems ran 16 hours each so far with no issues. Pushed 170MB of > >> data through the pair of serial ports on one system at 230400. > > > > The console on uart3 doesn't appear to be using the dma assuming the > > values in /sys for the dma controller and bytes transferred mean anything. > > It does mention in dmesg that it allocated dma channels for uart3 though. > > Then it should use it :) I managed to get something dma related on uart3. But it isn't happy: [ 95.577401] DMA misaligned error with device 53 repeated many times. I wonder if the dma support isn't quite working for the omap572x yet in this tree (ti's 3.12.y tree), or maybe it is picky and the driver still needs a bit of work. I have had no issues on uart7 and 8 without dma. > There is omap_8250_tx_dma() and omap_8250_rx_dma(). Both setup > callbacks (the rx+tx _complete). Upon successful DMA transfer you > should see them invoked with bytes transfered (>0). > For RX transfer you need at least trigger bytes in the FIFO within a > given time frame (I think it was 46 bytes and the delay may be up to 2 > bytes). If you miss this then DMA for RX won't wire and you purge the > FIFO manually via "timeout-interrupt" (the callback will be invoked > with an error condition and 0 bytes). > > Assuming this works for you then one should figure out why the counters > in /sys are not updated… -- Len Sorensen -- 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
