Hi Wen,

On Wed, Jul 17, 2019 at 05:23:53PM +0800, Wen He wrote:
> Configure the display Quality of service (QoS) levels to high priority
> if the level is defined as high as in DTS. The ARQOS for DP500 is driven
> from the "RQOS" register, needed to program the RQOS register value < 7
> for the 4k resolution flicker to disappear on the LS1028A platform.

Thanks for taking time to come up with a more generic patch for your issue!

I have a question: what happens if you program the MALIDP500_RQOS_QUALITY
register to 0xd000d000 for all pixelclocks?

Also, some suggestions further down:

> 
> Signed-off-by: Wen He <wen.h...@nxp.com>
> ---
> change in v2:
>         - add new implementation for 4k flicker issue on the LS1028A
> 
>  drivers/gpu/drm/arm/malidp_drv.c  |  5 +++++
>  drivers/gpu/drm/arm/malidp_hw.c   | 13 +++++++++++++
>  drivers/gpu/drm/arm/malidp_hw.h   |  3 +++
>  drivers/gpu/drm/arm/malidp_regs.h | 12 ++++++++++++
>  4 files changed, 33 insertions(+)
> 
> diff --git a/drivers/gpu/drm/arm/malidp_drv.c 
> b/drivers/gpu/drm/arm/malidp_drv.c
> index f25ec4382277..d2b2cf52ac87 100644
> --- a/drivers/gpu/drm/arm/malidp_drv.c
> +++ b/drivers/gpu/drm/arm/malidp_drv.c
> @@ -818,6 +818,11 @@ static int malidp_bind(struct device *dev)
>  
>       malidp->core_id = version;
>  
> +     hwdev->arqos_high_level = false;

This is not needed.

> +
> +     hwdev->arqos_high_level = of_property_read_bool(dev->of_node,
> +                                     "arm,malidp-arqos-high-level");

I think it would be better to have this property as a u32 value, rather than a
boolean, and put the value that we want to program MALIDP_RQOS_QUALITY with in
there.

Also, you need to add the documentation for this optional property in
Documentation/devicetree/bindings/display/arm,malidp.txt.

> +
>       /* set the number of lines used for output of RGB data */
>       ret = of_property_read_u8_array(dev->of_node,
>                                       "arm,malidp-output-port-lines",
> diff --git a/drivers/gpu/drm/arm/malidp_hw.c b/drivers/gpu/drm/arm/malidp_hw.c
> index 50af399d7f6f..eaa1658cd86b 100644
> --- a/drivers/gpu/drm/arm/malidp_hw.c
> +++ b/drivers/gpu/drm/arm/malidp_hw.c
> @@ -374,6 +374,19 @@ static void malidp500_modeset(struct malidp_hw_device 
> *hwdev, struct videomode *
>               malidp_hw_setbits(hwdev, MALIDP_DISP_FUNC_ILACED, 
> MALIDP_DE_DISPLAY_FUNC);
>       else
>               malidp_hw_clearbits(hwdev, MALIDP_DISP_FUNC_ILACED, 
> MALIDP_DE_DISPLAY_FUNC);
> +
> +     /*
> +      *  Program the RQoS register to increasing QoS levels for
> +      *  the 4k resolution flicker to disappear on the LS1028A.

Looks like two sentences got smashed into one, the result is a bit hard to read.

Best regards,
Liviu

> +      */
> +     if (hwdev->arqos_high_level) {
> +             val = RED_ARQOS_VALUE | GREEN_ARQOS_VALUE;
> +
> +             if (mode->pixelclock == 594000000)
> +                     malidp_hw_setbits(hwdev, val, MALIDP500_RQOS_QUALITY);
> +             else
> +                     malidp_hw_clearbits(hwdev, val, MALIDP500_RQOS_QUALITY);
> +     }
>  }
>  
>  int malidp_format_get_bpp(u32 fmt)
> diff --git a/drivers/gpu/drm/arm/malidp_hw.h b/drivers/gpu/drm/arm/malidp_hw.h
> index 968a65eed371..b8baba60508a 100644
> --- a/drivers/gpu/drm/arm/malidp_hw.h
> +++ b/drivers/gpu/drm/arm/malidp_hw.h
> @@ -251,6 +251,9 @@ struct malidp_hw_device {
>  
>       /* size of memory used for rotating layers, up to two banks available */
>       u32 rotation_memory[2];
> +
> +     /* priority level of RQOS register used for driven the ARQOS signal */
> +     bool arqos_high_level;
>  };
>  
>  static inline u32 malidp_hw_read(struct malidp_hw_device *hwdev, u32 reg)
> diff --git a/drivers/gpu/drm/arm/malidp_regs.h 
> b/drivers/gpu/drm/arm/malidp_regs.h
> index 993031542fa1..08842142b3b2 100644
> --- a/drivers/gpu/drm/arm/malidp_regs.h
> +++ b/drivers/gpu/drm/arm/malidp_regs.h
> @@ -210,6 +210,18 @@
>  #define MALIDP500_CONFIG_VALID               0x00f00
>  #define MALIDP500_CONFIG_ID          0x00fd4
>  
> +/*
> + * The quality of service (QoS) register on the DP500. RQOS register values
> + * are driven by the ARQOS signal, using AXI transacations, dependent on the
> + * FIFO input level.
> + * The RQOS register can also set QoS levels for:
> + *    - RED_ARQOS   @ A 4-bit signal value for close to underflow conditions
> + *    - GREEN_ARQOS @ A 4-bit signal value for normal conditions
> + */
> +#define MALIDP500_RQOS_QUALITY          0x00500
> +#define RED_ARQOS_VALUE                 (0xd << 12)
> +#define GREEN_ARQOS_VALUE               (0xd << 28)
> +
>  /* register offsets and bits specific to DP550/DP650 */
>  #define MALIDP550_ADDR_SPACE_SIZE    0x10000
>  #define MALIDP550_DE_CONTROL         0x00010
> -- 
> 2.17.1
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
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