Re: [PATCH 2/2] tty: serial: imx: don't reinit clock with enabled console

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On 8/28/2012 3:46 AM, Dirk Behme wrote:
On 27.08.2012 20:20, Troy Kisky wrote:
On 8/27/2012 12:36 AM, Dirk Behme wrote:
From: Xinyu Chen <xinyu.chen@xxxxxxxxxxxxx>

Remove the imx_setup_ufcr() call on startup when CONSOLE enabled,
as this will cause clock reinit, and output garbage.

This patch is a port from Freescale's Android kernel.

Signed-off-by: Xinyu Chen <xinyu.chen@xxxxxxxxxxxxx>
Tested-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
CC: Shawn Guo <shawn.guo@xxxxxxxxxx>
CC: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
  drivers/tty/serial/imx.c |    2 ++
  1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 908178f..31ce414 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -695,7 +695,9 @@ static int imx_startup(struct uart_port *port)
      int retval;
      unsigned long flags, temp;
  +#ifndef CONFIG_SERIAL_CORE_CONSOLE
      imx_setup_ufcr(sport, 0);
+#endif
        /* disable the DREN bit (Data Ready interrupt enable) before
       * requesting IRQs


I'd rather do something like this

static int imx_setup_ufcr(struct imx_port *sport, unsigned int mode)
{
         unsigned int val;

         /* set receiver / transmitter trigger level. */
         val = readl(sport->port.membase + UFCR) & UFCR_RFDIV;

Shouldn't it be

... & (UFCR_RFDIV | UFCR_DCEDTE);

then? My i.MX6 manual has DCEDTE as bit 6, which we don't want to touch, too? We only want to touch TXTL and RXTL?


If you do that, you should also change imx_set_termios
to possibly clear the bit

new_ufcr = (old_ufcr & (~UFCR_RFDIV)) | UFCR_RFDIV_REG(div);

to

new_ufcr = (old_ufcr & (~(UFCR_RFDIV | UFCR_DCEDTE))) | UFCR_RFDIV_REG(div);

         val |= TXTL << 10 | RXTL;
         writel(val, sport->port.membase + UFCR);
         return 0;
}

There is no need for imx_setup_ufcr to change divisor.

Ok

Thanks

Dirk


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