[U-Boot] [PATCH v1 2/3] imx: serial_mxc: disable ri and dcd irq in dte mode

[Stefano Babic]

Hi Marcel,

On 01/02/19 16:04, Marcel Ziswiler wrote:
> From: Max Krummenacher <max.krummenacher at toradex.com>
> 
> If the UART is used in DTE mode the RI and DCD bits in UCR3 become
> irq enable bits. Both are set to enabled after reset and both likely
> are pending.
> 
> Disable the bits to prevent an interrupt storm when Linux enables
> the UART interrupts.
> 
> Signed-off-by: Max Krummenacher <max.krummenacher at toradex.com>
> Signed-off-by: Marcel Ziswiler <marcel.ziswiler at toradex.com>
> 
> ---
> 

I never seen this issue, but you fix looks plausible - I applied this to
my working branch and queued for next PR.

Regards,
Stefano

>  drivers/serial/serial_mxc.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c
> index 7e4e6d36b8..df35ac9114 100644
> --- a/drivers/serial/serial_mxc.c
> +++ b/drivers/serial/serial_mxc.c
> @@ -138,13 +138,18 @@ struct mxc_uart {
>  	u32 ts;
>  };
>  
> -static void _mxc_serial_init(struct mxc_uart *base)
> +static void _mxc_serial_init(struct mxc_uart *base, int use_dte)
>  {
>  	writel(0, &base->cr1);
>  	writel(0, &base->cr2);
>  
>  	while (!(readl(&base->cr2) & UCR2_SRST));
>  
> +	if (use_dte)
> +		writel(0x404 | UCR3_ADNIMP, &base->cr3);
> +	else
> +		writel(0x704 | UCR3_ADNIMP, &base->cr3);
> +
>  	writel(0x704 | UCR3_ADNIMP, &base->cr3);
>  	writel(0x8000, &base->cr4);
>  	writel(0x2b, &base->esc);
> @@ -226,7 +231,7 @@ static int mxc_serial_tstc(void)
>   */
>  static int mxc_serial_init(void)
>  {
> -	_mxc_serial_init(mxc_base);
> +	_mxc_serial_init(mxc_base, false);
>  
>  	serial_setbrg();
>  
> @@ -271,7 +276,7 @@ static int mxc_serial_probe(struct udevice *dev)
>  {
>  	struct mxc_serial_platdata *plat = dev->platdata;
>  
> -	_mxc_serial_init(plat->reg);
> +	_mxc_serial_init(plat->reg, plat->use_dte);
>  
>  	return 0;
>  }
> @@ -367,7 +372,7 @@ static inline void _debug_uart_init(void)
>  {
>  	struct mxc_uart *base = (struct mxc_uart *)CONFIG_DEBUG_UART_BASE;
>  
> -	_mxc_serial_init(base);
> +	_mxc_serial_init(base, false);
>  	_mxc_serial_setbrg(base, CONFIG_DEBUG_UART_CLOCK,
>  			   CONFIG_BAUDRATE, false);
>  }
> 


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