[PATCH] drm: panel: simple: Drop drive/sample bus flags for LVDS panels

[Sam Ravnborg]

On Sun, Jun 28, 2020 at 10:54:01AM +0300, Laurent Pinchart wrote:
> The DRM bus flags reporting on which clock edge the pixel data and sync
> signals are sampled or driven don't make sense for LVDS panels, as the
> bus then uses sub-clock timings to send data. Drop those flags and add a
> warning in the probe function to make sure the mistake won't be
> repeated.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
> ---
>  drivers/gpu/drm/panel/panel-simple.c | 30 +++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index bff1cab529d2..537d75ef7fc2 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -549,6 +549,14 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>  			panel_simple_parse_panel_timing_node(dev, panel, &dt);
>  	}
>  
> +	if (desc->connector_type == DRM_MODE_CONNECTOR_LVDS)
> +		/* Catch common mistakes for LVDS panels. */
> +		WARN_ON(desc->bus_flags &
> +			(DRM_BUS_FLAG_PIXDATA_POSEDGE |
> +			 DRM_BUS_FLAG_PIXDATA_NEGEDGE |
> +			 DRM_BUS_FLAG_SYNC_POSEDGE |
> +			 DRM_BUS_FLAG_SYNC_NEGEDGE));
The above are only the legacy flags.
For LVDS panels I think we could check if either
DRM_BUS_FLAG_DE_LOW or DRM_BUS_FLAG_DE_HIGH is set and nothing else.
And then as an additional check that the .bus_format is relevant.

Then we have managed to catch most of the mistakes for LVDS panels.

We could add checks for DPI panels too, but that would be later.

	Sam

> +
>  	drm_panel_init(&panel->base, dev, &panel_simple_funcs,
>  		       desc->connector_type);
>  
> @@ -688,7 +696,7 @@ static const struct panel_desc auo_b101aw03 = {
>  		.height = 125,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -1398,7 +1406,7 @@ static const struct panel_desc chunghwa_claa070wp03xg = {
>  		.height = 150,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -1423,7 +1431,7 @@ static const struct panel_desc chunghwa_claa101wa01a = {
>  		.height = 120,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -1448,7 +1456,7 @@ static const struct panel_desc chunghwa_claa101wb01 = {
>  		.height = 125,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -2123,7 +2131,7 @@ static const struct panel_desc innolux_n156bge_l21 = {
>  		.height = 193,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -2256,7 +2264,7 @@ static const struct panel_desc koe_tx26d202vm0bwa = {
>  		.disable = 1000,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -2497,9 +2505,7 @@ static const struct panel_desc logictechno_lt170410_2whc = {
>  		.height = 136,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH |
> -		     DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE |
> -		     DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -3072,7 +3078,7 @@ static const struct panel_desc samsung_ltn101nt05 = {
>  		.height = 125,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -3319,7 +3325,7 @@ static const struct panel_desc starry_kr070pe2t = {
>  		.height = 86,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> @@ -3512,7 +3518,7 @@ static const struct panel_desc toshiba_lt089ac29000 = {
>  		.height = 116,
>  	},
>  	.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,
> -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> -- 
> Regards,
> 
> Laurent Pinchart