cpm1: don't send break on TX_STOP, don't interrupt RX/TX when adjusting termios parameters

Before setting STOP_TX, set _brkcr to 0 so the SMC does not send a break
character.  The driver appears to properly re-initialize _brkcr when the
SMC is restarted.

Do not interrupt RX/TX when the termios is being adjusted; it results in
corrupted characters appearing on the line.

Cc: Vitaly Bordug <vbordug@ru.mvista.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/serial/cpm_uart/cpm_uart_core.c b/drivers/serial/cpm_uart/cpm_uart_core.c
index 1ff80de177db..a4f86927a74b 100644
--- a/drivers/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/serial/cpm_uart/cpm_uart_core.c
@@ -435,10 +435,13 @@ static void cpm_uart_shutdown(struct uart_port *port)
                 }
 
                 /* Shut them really down and reinit buffer descriptors */
-                if (IS_SMC(pinfo))
+                if (IS_SMC(pinfo)) {
+                        out_be16(&pinfo->smcup->smc_brkcr, 0);
                         cpm_line_cr_cmd(pinfo, CPM_CR_STOP_TX);
-                else
+                } else {
+                        out_be16(&pinfo->sccup->scc_brkcr, 0);
                         cpm_line_cr_cmd(pinfo, CPM_CR_GRA_STOP_TX);
+                }
 
                 cpm_uart_initbd(pinfo);
         }
@@ -554,9 +557,11 @@ static void cpm_uart_set_termios(struct uart_port *port,
                  * enables, because we want to put them back if they were
                  * present.
                  */
-                prev_mode = in_be16(&smcp->smc_smcmr);
-                out_be16(&smcp->smc_smcmr, smcr_mk_clen(bits) | cval | SMCMR_SM_UART);
-                setbits16(&smcp->smc_smcmr, (prev_mode & (SMCMR_REN | SMCMR_TEN)));
+                prev_mode = in_be16(&smcp->smc_smcmr) & (SMCMR_REN | SMCMR_TEN);
+                /* Output in *one* operation, so we don't interrupt RX/TX if they
+                 * were already enabled. */
+                out_be16(&smcp->smc_smcmr, smcr_mk_clen(bits) | cval |
+                    SMCMR_SM_UART | prev_mode);
         } else {
                 out_be16(&sccp->scc_psmr, (sbits << 12) | scval);
         }
@@ -1198,12 +1203,14 @@ static int __init cpm_uart_console_setup(struct console *co, char *options)
         udbg_putc = NULL;
 #endif
 
-        cpm_line_cr_cmd(pinfo, CPM_CR_STOP_TX);
-
         if (IS_SMC(pinfo)) {
+                out_be16(&pinfo->smcup->smc_brkcr, 0);
+                cpm_line_cr_cmd(pinfo, CPM_CR_STOP_TX);
                 clrbits8(&pinfo->smcp->smc_smcm, SMCM_RX | SMCM_TX);
                 clrbits16(&pinfo->smcp->smc_smcmr, SMCMR_REN | SMCMR_TEN);
         } else {
+                out_be16(&pinfo->sccup->scc_brkcr, 0);
+                cpm_line_cr_cmd(pinfo, CPM_CR_GRA_STOP_TX);
                 clrbits16(&pinfo->sccp->scc_sccm, UART_SCCM_TX | UART_SCCM_RX);
                 clrbits32(&pinfo->sccp->scc_gsmrl, SCC_GSMRL_ENR | SCC_GSMRL_ENT);
         }