The patch titled
serial: MPSC: Remove race between Rx stop & restart
has been removed from the -mm tree. Its filename was
serial-mpsc-remove-race-between-rx-stop-restart.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: serial: MPSC: Remove race between Rx stop & restart
From: Carlos Sanchez <carlos.sanchez@xxxxxxxxxxx>
The patch in commit ID f7232056bff5fe2d3bfeab35252a66ebaeb5bbde 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 <carlos.sanchez@xxxxxxxxxxx>
Signed-off-by: Mark A. Greer <mgreer@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/serial/mpsc.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff -puN drivers/serial/mpsc.c~serial-mpsc-remove-race-between-rx-stop-restart drivers/serial/mpsc.c
--- a/drivers/serial/mpsc.c~serial-mpsc-remove-race-between-rx-stop-restart
+++ a/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;
}
_
Patches currently in -mm which might be from carlos.sanchez@xxxxxxxxxxx are
origin.patch
-
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