Re: [U-Boot] [PATCH V2 09/14] video: mxsfb: introduce lcdif_power_down

[Stefano Babic]

Hi Peng,

On 20/10/2015 13:39, Peng Fan wrote:
> Introudce a new function lcdif_power_down.
> 
> 1. Waits for a VSYNC interrupt to guarantee the reset is done at the
>    VSYNC edge, which somehow makes the LCDIF consume the display FIFO(?)
>    and helps the LCDIF work normally at the kernel stage.
> 2. Add power down function to stop lcdif.
> 
> The reason to introduce lcdif_power_down is that we want lcdif to be in
> initial state when doing uboot reset or before kernel boot to make
> system stable, otherwise system may hang.
> 

The explanation is independent from the processor type. But checking in
the next patch, this code runs only for 6UL. Why not for the 6sx ?


> Signed-off-by: Peng Fan <peng....@freescale.com>
> Cc: Stefano Babic <sba...@denx.de>
> Cc: Anatolij Gustschin <ag...@denx.de>
> ---
> 
> V2:
>  none
> 
>  arch/arm/include/asm/imx-common/sys_proto.h |  2 ++
>  drivers/video/mxsfb.c                       | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/arch/arm/include/asm/imx-common/sys_proto.h 
> b/arch/arm/include/asm/imx-common/sys_proto.h
> index 5673fb4..386c2dc 100644
> --- a/arch/arm/include/asm/imx-common/sys_proto.h
> +++ b/arch/arm/include/asm/imx-common/sys_proto.h
> @@ -47,6 +47,8 @@ int fecmxc_initialize(bd_t *bis);
>  u32 get_ahb_clk(void);
>  u32 get_periph_clk(void);
>  
> +void lcdif_power_down(void);
> +
>  int mxs_reset_block(struct mxs_register_32 *reg);
>  int mxs_wait_mask_set(struct mxs_register_32 *reg, u32 mask, u32 timeout);
>  int mxs_wait_mask_clr(struct mxs_register_32 *reg, u32 mask, u32 timeout);
> diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
> index eed57d5..ddbb118 100644
> --- a/drivers/video/mxsfb.c
> +++ b/drivers/video/mxsfb.c
> @@ -131,6 +131,23 @@ static void mxs_lcd_init(GraphicDevice *panel,
>       writel(LCDIF_CTRL_RUN, &regs->hw_lcdif_ctrl_set);
>  }
>  
> +void lcdif_power_down(void)
> +{
> +     struct mxs_lcdif_regs *regs = (struct mxs_lcdif_regs *)MXS_LCDIF_BASE;
> +     int timeout = 1000000;
> +
> +     writel(panel.frameAdrs, &regs->hw_lcdif_cur_buf_reg);
> +     writel(panel.frameAdrs, &regs->hw_lcdif_next_buf_reg);
> +     writel(LCDIF_CTRL1_VSYNC_EDGE_IRQ, &regs->hw_lcdif_ctrl1_clr);
> +     while (--timeout) {
> +             if (readl(&regs->hw_lcdif_ctrl1_reg) &
> +                 LCDIF_CTRL1_VSYNC_EDGE_IRQ)
> +                     break;
> +             udelay(1);
> +     }
> +     mxs_reset_block((struct mxs_register_32 *)&regs->hw_lcdif_ctrl_reg);
> +}
> +
>  void *video_hw_init(void)
>  {
>       int bpp = -1;
> 

Best regards,
Stefano Babic

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