On 11/20/2015 12:05 PM, Sören Brinkmann wrote: > On Fri, 2015-11-20 at 07:13AM -0500, Peter Hurley wrote: >> >> >> On 11/19/2015 03:02 PM, Soren Brinkmann wrote: >>> start_tx must start transmitting characters. Regardless of the state of >>> the circular buffer, always enable the transmitter hardware. >> >> Why? >> >> Does cdns_uart_stop_tx() actually stop the transmitter so that >> data remains in the transmitter? > > Fixing up the patch, I looked at this one. It might actually do that.
Ok. > Without having changed anything. The doc says: "The driver should > stop transmitting characters as soon as possible.". And the > implementation is really not draining any FIFO, but just disabling the > transmitter. I take your question as that this might not be this way? > Should stop_tx drain the FIFO first? No. Most h/w can't actually stop the transmitter (or not without losing data), so that's why the expectation is only for "as soon as possible". Stopping sooner is better. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
