From: Steve Twiss <stwiss.opensource@xxxxxxxxxxx>
Revert the commit e61c38d85b7392e ("serial: imx: setup DCEDTE early and
ensure DCD and RI irqs to be off")
The patch submitted to setup DCEDTE early and ensure DCD and RI irqs to
be off, causes a serial console display problem the i.MX6Q SABRESD board.
The console becomes unreadable and unwritable.
Tested-by: Steve Twiss <stwiss.opensource@xxxxxxxxxxx>
Signed-off-by: Steve Twiss <stwiss.opensource@xxxxxxxxxxx>
---
This patch applies against linux-next and v4.12-rc2
Hi,
I have been seeing a problem with the serial output console on the i.MX6Q
SABRESD, but not the i.MX6DL SABRESD. Everything was fine up to
linux-mainline/v4.11 but changed after linux-next/next-20170501.
Some bisection has pointed at the commit
e61c38d85b7392e033ee03bca46f1d6006156175 which, once removed from my
linux-next/v4.12-rc2 build allows the i.MX6Q board to display the console
correctly again.
This patch removes the original commit e61c38d85b7392e ("serial: imx:
setup DCEDTE early and ensure DCD and RI irqs to be off") from linux-next
v4.12-rc2 and fixes the serial problem seen in the i.MX6Q SABRESD board.
Regards,
Steve Twiss, Dialog Semiconductor Ltd.
drivers/tty/serial/imx.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 33509b4..b4340b5 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1325,10 +1325,19 @@ static int imx_startup(struct uart_port *port)
if (!is_imx1_uart(sport)) {
temp = readl(sport->port.membase + UCR3);
- temp |= UCR3_DTRDEN | UCR3_RI | UCR3_DCD;
+ /*
+ * The effect of RI and DCD differs depending on the UFCR_DCEDTE
+ * bit. In DCE mode they control the outputs, in DTE mode they
+ * enable the respective irqs. At least the DCD irq cannot be
+ * cleared on i.MX25 at least, so it's not usable and must be
+ * disabled. I don't have test hardware to check if RI has the
+ * same problem but I consider this likely so it's disabled for
+ * now, too.
+ */
+ temp |= IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP |
+ UCR3_DTRDEN | UCR3_RI | UCR3_DCD;
if (sport->dte_mode)
- /* disable broken interrupts */
temp &= ~(UCR3_RI | UCR3_DCD);
writel(temp, sport->port.membase + UCR3);
@@ -1610,6 +1619,8 @@ static void imx_flush_buffer(struct uart_port *port)
ufcr = readl(sport->port.membase + UFCR);
ufcr = (ufcr & (~UFCR_RFDIV)) | UFCR_RFDIV_REG(div);
+ if (sport->dte_mode)
+ ufcr |= UFCR_DCEDTE;
writel(ufcr, sport->port.membase + UFCR);
writel(num, sport->port.membase + UBIR);
@@ -2177,27 +2188,6 @@ static int serial_imx_probe(struct platform_device *pdev)
UCR1_TXMPTYEN | UCR1_RTSDEN);
writel_relaxed(reg, sport->port.membase + UCR1);
- if (!is_imx1_uart(sport) && sport->dte_mode) {
- /*
- * The DCEDTE bit changes the direction of DSR, DCD, DTR and RI
- * and influences if UCR3_RI and UCR3_DCD changes the level of RI
- * and DCD (when they are outputs) or enables the respective
- * irqs. So set this bit early, i.e. before requesting irqs.
- */
- writel(UFCR_DCEDTE, sport->port.membase + UFCR);
-
- /*
- * Disable UCR3_RI and UCR3_DCD irqs. They are also not
- * enabled later because they cannot be cleared
- * (confirmed on i.MX25) which makes them unusable.
- */
- writel(IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP | UCR3_DSR,
- sport->port.membase + UCR3);
-
- } else {
- writel(0, sport->port.membase + UFCR);
- }
-
clk_disable_unprepare(sport->clk_ipg);
/*
--
end-of-patch for PATCH V1
--
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