[PATCH 2/2] drm/bridge: ti-sn65dsi83: add h/vsync-disable support

[Dmitry Baryshkov]

On Thu, Mar 06, 2025 at 10:11:33AM +0100, A. Zini wrote:
> From: Alessandro Zini <alessandro.zini at siemens.com>
> 
> The h/vsync-disable properties are used to control whether to use or
> not h/vsync signals, by configuring their pulse width to zero.
> 
> This is required on some panels which are driven in DE-only mode but do
> not ignore sync packets, and instead require them to be low-voltage level
> or ground.

If this is required by 'some panels', then it should be a property of
the panel, not by the bridge itself. Can the panel return the mode with
hsync_end = hsync_start and vsync_enc = vsync_start?

> 
> Signed-off-by: Alessandro Zini <alessandro.zini at siemens.com>
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi83.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index 95563aa1b450d..c94ea92159402 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -164,6 +164,8 @@ struct sn65dsi83 {
>  	int				irq;
>  	struct delayed_work		monitor_work;
>  	struct work_struct		reset_work;
> +	bool				hsync_disable;
> +	bool				vsync_disable;
>  };
>  
>  static const struct regmap_range sn65dsi83_readable_ranges[] = {
> @@ -604,10 +606,12 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
>  	/* 32 + 1 pixel clock to ensure proper operation */
>  	le16val = cpu_to_le16(32 + 1);
>  	regmap_bulk_write(ctx->regmap, REG_VID_CHA_SYNC_DELAY_LOW, &le16val, 2);
> -	le16val = cpu_to_le16(mode->hsync_end - mode->hsync_start);
> +	le16val = cpu_to_le16(ctx->hsync_disable ?
> +		0 : mode->hsync_end - mode->hsync_start);
>  	regmap_bulk_write(ctx->regmap, REG_VID_CHA_HSYNC_PULSE_WIDTH_LOW,
>  			  &le16val, 2);
> -	le16val = cpu_to_le16(mode->vsync_end - mode->vsync_start);
> +	le16val = cpu_to_le16(ctx->vsync_disable ?
> +		0 : mode->vsync_end - mode->vsync_start);
>  	regmap_bulk_write(ctx->regmap, REG_VID_CHA_VSYNC_PULSE_WIDTH_LOW,
>  			  &le16val, 2);
>  	regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_BACK_PORCH,
> @@ -867,6 +871,14 @@ static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
>  		}
>  	}
>  
> +	ctx->hsync_disable = false;
> +	if (of_property_present(dev->of_node, "hsync-disable"))
> +		ctx->hsync_disable = true;
> +
> +	ctx->vsync_disable = false;
> +	if (of_property_present(dev->of_node, "vsync-disable"))
> +		ctx->vsync_disable = true;
> +
>  	panel_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 2, 0);
>  	if (IS_ERR(panel_bridge))
>  		return dev_err_probe(dev, PTR_ERR(panel_bridge), "Failed to get panel bridge\n");
> -- 
> 2.48.1
> 

-- 
With best wishes
Dmitry