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5816269e4e
In the (default) PIO mode, use a one-byte RX FIFO threshold. The OMAP UART IP blocks do not appear to be capable of waking the system under an RX timeout condition. Since the previous RX FIFO threshold was 16 bytes, this meant that omap-serial.c did not become aware of any received data until all those bytes arrived or until another UART interrupt occurred. This made the serial console and presumably other serial applications (GPS, serial Bluetooth) unusable or extremely slow. A 1-byte RX FIFO threshold also allows the MPU to enter a low-power consumption state while waiting for the FIFO to fill. This can be verified using the serial console by comparing the behavior when "0123456789abcde" is pasted in from another window, with the behavior when "0123456789abcdef" is pasted in. Since the former string is less than sixteen bytes long, the string is not echoed for some time, while the latter string is echoed immediately. DMA operation is unaffected by this patch. Thanks to Russell King - ARM Linux <linux@arm.linux.org.uk> for some additional information on the standard behavior of the RX timeout event, which was used to improve this commit description. Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com> Cc: Govindraj Raja <govindraj.r@ti.com> Cc: Alan Cox <alan@linux.intel.com> Cc: Russell King <linux@arm.linux.org.uk> Reviewed-by: Kevin Hilman <khilman@ti.com> Tested-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| hvc | ||
| ipwireless | ||
| serial | ||
| vt | ||
| amiserial.c | ||
| bfin_jtag_comm.c | ||
| cyclades.c | ||
| ehv_bytechan.c | ||
| isicom.c | ||
| Kconfig | ||
| Makefile | ||
| moxa.c | ||
| moxa.h | ||
| mxser.c | ||
| mxser.h | ||
| n_gsm.c | ||
| n_hdlc.c | ||
| n_r3964.c | ||
| n_tracerouter.c | ||
| n_tracesink.c | ||
| n_tracesink.h | ||
| n_tty.c | ||
| nozomi.c | ||
| pty.c | ||
| rocket_int.h | ||
| rocket.c | ||
| rocket.h | ||
| synclink_gt.c | ||
| synclink.c | ||
| synclinkmp.c | ||
| sysrq.c | ||
| tty_audit.c | ||
| tty_buffer.c | ||
| tty_io.c | ||
| tty_ioctl.c | ||
| tty_ldisc.c | ||
| tty_mutex.c | ||
| tty_port.c | ||