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

[Peng Fan]

Hi Stefano,

On Tue, Oct 20, 2015 at 03:59:18PM +0200, Stefano Babic wrote:
>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 ?

We met the issue on i.MX6UL EVK, but did not met issue on i.MX6SX SDB.
So I add the check. After a thought, it should be open to CONFIG_VIDEO_MXS.

To those which use LPDDR2 or LPDDR3, if LCDIF is enabled, lcdif_power_down
is a must, since there is no reset pin as DDR3. No reset pin will make
ddr not stable. Anyway lcdif_power_down do not hurts to those use DDR3.


Will use
#ifdef CONFIG_VIDEO_MXS
lcdif_power_down();
#endif

Regards,
Peng.

>
>
>> Signed-off-by: Peng Fan <Peng.Fan at freescale.com>
>> Cc: Stefano Babic <sbabic at denx.de>
>> Cc: Anatolij Gustschin <agust at 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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