[U-Boot] [PATCH] video: ipuv3_fb: skip IPU shutdown if IPU was not enabled before

[Stefano Babic]

Hi Anatolji,

On 25/08/2017 15:10, Anatolij Gustschin wrote:
> Boards can skip display interface init using board_video_skip().
> If display interface was not initialized (e.g. no ipuv3 framebuffer
> registered or IPU clock disabled), booting Linux stops due to the
> crash in IPU shutdown function, when accessing IPU registers.
> Check IPU clock and skip shutdown if clock is not enabled.
> 
> Signed-off-by: Anatolij Gustschin <agust at denx.de>
> ---
>  drivers/video/mxc_ipuv3_fb.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/video/mxc_ipuv3_fb.c b/drivers/video/mxc_ipuv3_fb.c
> index 0d0a0a9..8836229 100644
> --- a/drivers/video/mxc_ipuv3_fb.c
> +++ b/drivers/video/mxc_ipuv3_fb.c
> @@ -13,6 +13,7 @@
>  
>  #include <common.h>
>  #include <linux/errno.h>
> +#include <asm/arch/crm_regs.h>
>  #include <asm/global_data.h>
>  #include <linux/string.h>
>  #include <linux/list.h>
> @@ -568,8 +569,18 @@ err0:
>  
>  void ipuv3_fb_shutdown(void)
>  {
> -	int i;
> +	struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;
>  	struct ipu_stat *stat = (struct ipu_stat *)IPU_STAT;
> +	u32 reg;
> +	int i;
> +
> +	/*
> +	 * Check if IPU clock was enabled before. Won't access
> +	 * IPU registers if clock is not enabled.
> +	 */
> +	reg = readl(&mxc_ccm->CCGR3);
> +	if ((reg & MXC_CCM_CCGR3_IPU1_IPU_MASK) == 0)
> +		return;
>  

It looks to me quite weak to simply check if clock is gated. On some
board clock is gated even if IPU is not active. Do you have a way
reading inside IPU itself ? Then we can better decide if it was really
acrive. For example, checking if ipu_enable_channel() was called (and
DMA registers are set).

Best regards,
Stefano


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