Re: [PATCH v2 05/13] drm/bridge: lt9611: fix clock calculation

[Neil Armstrong <neil.armstrong@xxxxxxxxxx>]

On 08/01/2023 17:56, Dmitry Baryshkov wrote:
> Instead of having several fixed values for the pcr register, calculate
> it before programming. This allows the bridge to support most of the
> display modes.
>
> Fixes: 23278bf54afe ("drm/bridge: Introduce LT9611 DSI to HDMI bridge")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/bridge/lontium-lt9611.c | 32 +++++++++++--------------
>   1 file changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
> index f377052a45a4..e2799a0df8f8 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt9611.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
> @@ -192,8 +192,9 @@ static void lt9611_mipi_video_setup(struct lt9611 *lt9611,
>   	regmap_write(lt9611->regmap, 0x831b, (u8)(hsync_porch % 256));
>   }
>   
> -static void lt9611_pcr_setup(struct lt9611 *lt9611, const struct drm_display_mode *mode)
> +static void lt9611_pcr_setup(struct lt9611 *lt9611, const struct drm_display_mode *mode, unsigned int postdiv)
>   {
> +	unsigned int pcr_m = mode->clock * 5 * postdiv / 27000;
>   	const struct reg_sequence reg_cfg[] = {
>   		{ 0x830b, 0x01 },
>   		{ 0x830c, 0x10 },
> @@ -236,24 +237,14 @@ static void lt9611_pcr_setup(struct lt9611 *lt9611, const struct drm_display_mod
>   	else
>   		regmap_multi_reg_write(lt9611->regmap, reg_cfg, ARRAY_SIZE(reg_cfg));
>   
> -	switch (mode->hdisplay) {
> -	case 640:
> -		regmap_write(lt9611->regmap, 0x8326, 0x14);
> -		break;
> -	case 1920:
> -		regmap_write(lt9611->regmap, 0x8326, 0x37);
> -		break;
> -	case 3840:
> -		regmap_write(lt9611->regmap, 0x8326, 0x37);
> -		break;
> -	}
> +	regmap_write(lt9611->regmap, 0x8326, pcr_m);
>   
>   	/* pcr rst */
>   	regmap_write(lt9611->regmap, 0x8011, 0x5a);
>   	regmap_write(lt9611->regmap, 0x8011, 0xfa);
>   }
>   
> -static int lt9611_pll_setup(struct lt9611 *lt9611, const struct drm_display_mode *mode)
> +static int lt9611_pll_setup(struct lt9611 *lt9611, const struct drm_display_mode *mode, unsigned int *postdiv)
>   {
>   	unsigned int pclk = mode->clock;
>   	const struct reg_sequence reg_cfg[] = {
> @@ -271,12 +262,16 @@ static int lt9611_pll_setup(struct lt9611 *lt9611, const struct drm_display_mode
>   
>   	regmap_multi_reg_write(lt9611->regmap, reg_cfg, ARRAY_SIZE(reg_cfg));
>   
> -	if (pclk > 150000)
> +	if (pclk > 150000) {
>   		regmap_write(lt9611->regmap, 0x812d, 0x88);
> -	else if (pclk > 70000)
> +		*postdiv = 1;
> +	} else if (pclk > 70000) {
>   		regmap_write(lt9611->regmap, 0x812d, 0x99);
> -	else
> +		*postdiv = 2;
> +	} else {
>   		regmap_write(lt9611->regmap, 0x812d, 0xaa);
> +		*postdiv = 4;
> +	}
>   
>   	/*
>   	 * first divide pclk by 2 first
> @@ -895,14 +890,15 @@ static void lt9611_bridge_mode_set(struct drm_bridge *bridge,
>   {
>   	struct lt9611 *lt9611 = bridge_to_lt9611(bridge);
>   	struct hdmi_avi_infoframe avi_frame;
> +	unsigned int postdiv;
>   	int ret;
>   
>   	lt9611_bridge_pre_enable(bridge);
>   
>   	lt9611_mipi_input_digital(lt9611, mode);
> -	lt9611_pll_setup(lt9611, mode);
> +	lt9611_pll_setup(lt9611, mode, &postdiv);
>   	lt9611_mipi_video_setup(lt9611, mode);
> -	lt9611_pcr_setup(lt9611, mode);
> +	lt9611_pcr_setup(lt9611, mode, postdiv);
>   
>   	ret = drm_hdmi_avi_infoframe_from_display_mode(&avi_frame,
>   						       &lt9611->connector,


Reviewed-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>