This reverts commit 1776fd059c40907297d6c26c51876575d63fd9e2. Commit 1776fd059c40 causes UART sluggishness on the OMAP37xx EVM. This can be demonstrated by pasting in a ten-character string, like "ffffffffff", at the serial console. The string will be echoed back two to three characters at a time, with about a one-second pause between groups. This causes one of the OMAP PM validation tests to time out:
http://www.pwsan.com/omap/testlogs/test_v3.9-rc5/20130331205513/pm/37xxevm/37xxevm_log.txt With commit 1776fd059c40 reverted, the test succeeds: http://www.pwsan.com/omap/testlogs/serial_fix_37xx_v3.9-rc/20130331230517/pm/37xxevm/37xxevm_log.txt This problem has been present since v3.9-rc1, but was incorrectly suspected to be due to commit 6aa9707099c4b25700940eb3d016f16c4434360d ("lockdep: check that no locks held at freeze time"), due to limitations in my local testbed. Signed-off-by: Paul Walmsley <[email protected]> Cc: Alexey Pelykh <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> --- Alexey, care to make another attempt for 3.11 at fixing the issue you were originally debugging, but one that also works on OMAP37xx EVM? It would be good to cc the <[email protected]> on your OMAP work. If you don't have a 37xx EVM, someone there might be able to help you test. drivers/tty/serial/omap-serial.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 4dc4140..9915e4d 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -59,7 +59,6 @@ /* SCR register bitmasks */ #define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK (1 << 7) -#define OMAP_UART_SCR_TX_TRIG_GRANU1_MASK (1 << 6) #define OMAP_UART_SCR_TX_EMPTY (1 << 3) /* FCR register bitmasks */ @@ -321,6 +320,9 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr) struct circ_buf *xmit = &up->port.state->xmit; int count; + if (!(lsr & UART_LSR_THRE)) + return; + if (up->port.x_char) { serial_out(up, UART_TX, up->port.x_char); up->port.icount.tx++; @@ -862,7 +864,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios, serial_out(up, UART_IER, up->ier); serial_out(up, UART_LCR, cval); /* reset DLAB */ up->lcr = cval; - up->scr = 0; + up->scr = OMAP_UART_SCR_TX_EMPTY; /* FIFOs and DMA Settings */ @@ -886,6 +888,8 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios, serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR); /* FIFO ENABLE, DMA MODE */ + up->scr |= OMAP_UART_SCR_RX_TRIG_GRANU1_MASK; + /* Set receive FIFO threshold to 16 characters and * transmit FIFO threshold to 16 spaces */ -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
