Re: [PATCH] drm: atmel-hlcdc: bypass LCDC pixel clock divider when using LCDC Generic Clock

[Lee Jones <lee@kernel.org>]

On Thu, 10 Oct 2024, Manikandan Muralidharan wrote:

> In sam9x7 SoC where XLCDC IP is used,add support to bypass the LCDC pixel
> clock divider when LCDC Generic clock is enabled.Used to match
> and drive the panel requested Pixel clock.
> 
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
> ---
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 8 +++++++-
>  include/linux/mfd/atmel-hlcdc.h                | 1 +

Acked-by: Lee Jones <lee@kernel.org>

>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> index 0f7ffb3ced20..c54770cecaa8 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
> @@ -146,13 +146,19 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
>  
>  		if (div_low >= 2 &&
>  		    (10 * (prate / div_low - mode_rate) <
> -		     (mode_rate - prate / div)))
> +		     (mode_rate - prate / div))) {
>  			/*
>  			 * At least 10 times better when using a higher
>  			 * frequency than requested, instead of a lower.
>  			 * So, go with that.
>  			 */
>  			div = div_low;
> +		} else {
> +			if (crtc->dc->desc->is_xlcdc) {
> +				cfg |= ATMEL_XLCDC_CLKBYP;
> +				mask |= ATMEL_XLCDC_CLKBYP;
> +			}
> +		}
>  	}
>  
>  	cfg |= ATMEL_HLCDC_CLKDIV(div);
> diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
> index 80d675a03b39..982f494e6307 100644
> --- a/include/linux/mfd/atmel-hlcdc.h
> +++ b/include/linux/mfd/atmel-hlcdc.h
> @@ -44,6 +44,7 @@
>  #define ATMEL_XLCDC_HEO_UPDATE		BIT(3)
>  
>  #define ATMEL_HLCDC_CLKPOL		BIT(0)
> +#define ATMEL_XLCDC_CLKBYP		BIT(1)
>  #define ATMEL_HLCDC_CLKSEL		BIT(2)
>  #define ATMEL_HLCDC_CLKPWMSEL		BIT(3)
>  #define ATMEL_HLCDC_CGDIS(i)		BIT(8 + (i))
> -- 
> 2.25.1
> 

-- 
Lee Jones [李琼斯]