From b473cad63cefd90559dd083a9a5fc09f854f23a2 Mon Sep 17 00:00:00 2001 From: Carlos Sanchez Date: Tue, 31 Jul 2007 00:38:59 -0700 Subject: [PATCH] serial: MPSC: Remove race between Rx stop & restart The patch in commit ID f8f0fae38828430b0400aa2f1443308ca517cde6 stops (aborts) the MPSC's receive engine just before restarting it. Unfortunately, it doesn't wait for the abort to complete before restarting it which creates a race between the abort and the restart. If the restart occurs first, the in-progress abort stops it again and the rx engine remains stopped. Instead, do the abort when the SDMA engine is being stopped. Make sure to wait for the abort to complete before continuing. Signed-off-by: Carlos Sanchez Signed-off-by: Mark A. Greer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/serial/mpsc.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/serial/mpsc.c b/drivers/serial/mpsc.c index 00924feaf6218..567fa789c5c77 100644 --- a/drivers/serial/mpsc.c +++ b/drivers/serial/mpsc.c @@ -1363,8 +1363,6 @@ mpsc_start_rx(struct mpsc_port_info *pi) { pr_debug("mpsc_start_rx[%d]: Starting...\n", pi->port.line); - /* Issue a Receive Abort to clear any receive errors */ - writel(MPSC_CHR_2_RA, pi->mpsc_base + MPSC_CHR_2); if (pi->rcv_data) { mpsc_enter_hunt(pi); mpsc_sdma_cmd(pi, SDMA_SDCM_ERD); @@ -1379,6 +1377,20 @@ mpsc_stop_rx(struct uart_port *port) pr_debug("mpsc_stop_rx[%d]: Stopping...\n", port->line); + if (pi->mirror_regs) { + writel(pi->MPSC_CHR_2_m | MPSC_CHR_2_RA, + pi->mpsc_base + MPSC_CHR_2); + /* Erratum prevents reading CHR_2 so just delay for a while */ + udelay(100); + } + else { + writel(readl(pi->mpsc_base + MPSC_CHR_2) | MPSC_CHR_2_RA, + pi->mpsc_base + MPSC_CHR_2); + + while (readl(pi->mpsc_base + MPSC_CHR_2) & MPSC_CHR_2_RA) + udelay(10); + } + mpsc_sdma_cmd(pi, SDMA_SDCM_AR); return; } -- 2.39.5