[U-Boot] [PATCH 1/1] ipu common: reset ipuv3 correctly

[Eric Nelson]

Hi Liu Ying,

On 10/06/2012 07:16 AM, Liu Ying wrote:
> From: Liu Ying<Ying.Liu at freescale.com>
>
> This patch checks self-clear sw_ipu_rst bit in
> SCR register of SRC controller to be cleared
> after setting it to high to reset IPUv3. This
> makes sure that IPUv3 finishes sofware reset.
> A timeout mechanism is added to stop polling
> on the bit status in case the bit could not be
> cleared by the hardware automatically within
> 10 millisecond.
>
> Signed-off-by: Liu Ying<Ying.Liu at freescale.com>
> ---
>   drivers/video/ipu_common.c |   10 ++++++++++
>   1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/video/ipu_common.c b/drivers/video/ipu_common.c
> index 2020da9..fcc1745 100644
> --- a/drivers/video/ipu_common.c
> +++ b/drivers/video/ipu_common.c
> @@ -94,6 +94,7 @@ struct ipu_ch_param {
>   	temp1; \
>   })
>
> +#define IPU_SW_RST_TOUT_USEC	(10000)
>
>   void clk_enable(struct clk *clk)
>   {
> @@ -392,11 +393,20 @@ void ipu_reset(void)
>   {
>   	u32 *reg;
>   	u32 value;
> +	int timeout = IPU_SW_RST_TOUT_USEC;
>
>   	reg = (u32 *)SRC_BASE_ADDR;
>   	value = __raw_readl(reg);
>   	value = value | SW_IPU_RST;
>   	__raw_writel(value, reg);
> +
> +	while (__raw_readl(reg)&  SW_IPU_RST) {
> +		udelay(1);
> +		if (!(timeout--)) {
> +			printf("ipu software reset timeout\n");
> +			break;
> +		}
> +	};
>   }
>
>   /*

Tested in the normal (successful) case on SABRE Lite.

Is there a situation under which this is known to fail or
is that a hypothetical?