Re: [PATCH v3 4/6] drm: lcdif: Check consistent bus format and flags across first bridges

[Alexander Stein]

Hi Liu,

thanks for the update.

Am Montag, 13. Februar 2023, 09:56:10 CET schrieb Liu Ying:
> The single LCDIF embedded in i.MX93 SoC may drive multiple displays
> simultaneously.  Check bus format and flags across first bridges in
> ->atomic_check() to ensure they are consistent.  This is a preparation
> for adding i.MX93 LCDIF support.
> 
> Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> ---
> v2->v3:
> * No change.
> 
> v1->v2:
> * Split from patch 2/2 in v1. (Marek, Alexander)
> * Drop a comment about bridge input bus format from
> lcdif_crtc_atomic_check().
> 
>  drivers/gpu/drm/mxsfb/lcdif_drv.c |  2 -
>  drivers/gpu/drm/mxsfb/lcdif_drv.h |  1 -
>  drivers/gpu/drm/mxsfb/lcdif_kms.c | 76 ++++++++++++++++++++++---------
>  3 files changed, 55 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> b/drivers/gpu/drm/mxsfb/lcdif_drv.c index cc2ceb301b96..b5b9a8e273c6 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> @@ -52,8 +52,6 @@ static int lcdif_attach_bridge(struct lcdif_drm_private
> *lcdif) if (ret)
>  		return dev_err_probe(drm->dev, ret, "Failed to attach 
bridge\n");
> 
> -	lcdif->bridge = bridge;
> -
>  	return 0;
>  }
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.h
> b/drivers/gpu/drm/mxsfb/lcdif_drv.h index 6cdba6e20c02..aa6d099a1897 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_drv.h
> +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.h
> @@ -31,7 +31,6 @@ struct lcdif_drm_private {
>  	} planes;
>  	struct drm_crtc			crtc;
>  	struct drm_encoder		encoder;
> -	struct drm_bridge		*bridge;
>  };
> 
>  static inline struct lcdif_drm_private *
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> b/drivers/gpu/drm/mxsfb/lcdif_kms.c index 294cecdf5439..4ea3d2b2cf61 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -17,6 +17,7 @@
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
>  #include <drm/drm_color_mgmt.h>
> +#include <drm/drm_connector.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_fb_dma_helper.h>
> @@ -424,15 +425,19 @@ static int lcdif_crtc_atomic_check(struct drm_crtc
> *crtc, struct drm_atomic_state *state)
>  {
>  	struct drm_device *drm = crtc->dev;
> -	struct lcdif_drm_private *lcdif = to_lcdif_drm_private(drm);
>  	struct drm_crtc_state *crtc_state = 
drm_atomic_get_new_crtc_state(state,
>  								
	  crtc);
>  	struct lcdif_crtc_state *lcdif_crtc_state =
> to_lcdif_crtc_state(crtc_state); bool has_primary = crtc_state->plane_mask
> &
>  			   drm_plane_mask(crtc->primary);
> +	struct drm_connector_state *connector_state;
> +	struct drm_connector *connector;
> +	struct drm_encoder *encoder;
>  	struct drm_bridge_state *bridge_state;
> -	struct drm_bridge *bridge = lcdif->bridge;
> -	int ret;
> +	struct drm_bridge *bridge;
> +	u32 bus_format, bus_flags;
> +	bool format_set = false, flags_set = false;
> +	int ret, i;
> 
>  	/* The primary plane has to be enabled when the CRTC is active. */
>  	if (crtc_state->active && !has_primary)
> @@ -442,26 +447,55 @@ static int lcdif_crtc_atomic_check(struct drm_crtc
> *crtc, if (ret)
>  		return ret;
> 
> -	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
> -	if (!bridge_state)
> -		lcdif_crtc_state->bus_format = MEDIA_BUS_FMT_FIXED;
> -	else
> -		lcdif_crtc_state->bus_format = bridge_state-
>input_bus_cfg.format;
> -
> -	if (lcdif_crtc_state->bus_format == MEDIA_BUS_FMT_FIXED) {
> -		dev_warn_once(drm->dev,
> -			      "Bridge does not provide bus format, 
assuming
> MEDIA_BUS_FMT_RGB888_1X24.\n" -			      "Please fix 
bridge driver by
> handling atomic_get_input_bus_fmts.\n"); -		lcdif_crtc_state-
>bus_format =
> MEDIA_BUS_FMT_RGB888_1X24;
> +	/* Try to find consistent bus format and flags across first bridges. 
*/
> +	for_each_new_connector_in_state(state, connector, connector_state, 
i) {
> +		if (!connector_state->crtc)
> +			continue;
> +
> +		encoder = connector_state->best_encoder;
> +
> +		bridge = drm_bridge_chain_get_first_bridge(encoder);
> +		if (!bridge)
> +			continue;
> +
> +		bridge_state = drm_atomic_get_new_bridge_state(state, 
bridge);
> +		if (!bridge_state)
> +			bus_format = MEDIA_BUS_FMT_FIXED;
> +		else
> +			bus_format = bridge_state->input_bus_cfg.format;
> +
> +		if (bus_format == MEDIA_BUS_FMT_FIXED) {
> +			dev_warn(drm->dev,
> +				 "[ENCODER:%d:%s]'s bridge does not 
provide bus format, assuming
> MEDIA_BUS_FMT_RGB888_1X24.\n" +				 
"Please fix bridge driver by handling
> atomic_get_input_bus_fmts.\n", +				 
encoder->base.id, encoder->name);
> +			bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> +		}
> +
> +		if (!format_set) {
> +			lcdif_crtc_state->bus_format = bus_format;
> +			format_set = true;
> +		} else if (lcdif_crtc_state->bus_format != bus_format) {
> +			DRM_DEV_DEBUG_DRIVER(drm->dev, "inconsistent bus 
format\n");

Is there another way to know the actual reason the atomic_check fails? Maybe 
this is worthy to be an error message instead.

Best regards,
Alexander

> +			return -EINVAL;
> +		}
> +
> +		if (bridge->timings)
> +			bus_flags = bridge->timings->input_bus_flags;
> +		else if (bridge_state)
> +			bus_flags = bridge_state->input_bus_cfg.flags;
> +		else
> +			bus_flags = 0;
> +
> +		if (!flags_set) {
> +			lcdif_crtc_state->bus_flags = bus_flags;
> +			flags_set = true;
> +		} else if (lcdif_crtc_state->bus_flags != bus_flags) {
> +			DRM_DEV_DEBUG_DRIVER(drm->dev, "inconsistent bus 
flags\n");
> +			return -EINVAL;
> +		}
>  	}
> 
> -	if (bridge->timings)
> -		lcdif_crtc_state->bus_flags = bridge->timings-
>input_bus_flags;
> -	else if (bridge_state)
> -		lcdif_crtc_state->bus_flags = bridge_state-
>input_bus_cfg.flags;
> -	else
> -		lcdif_crtc_state->bus_flags = 0;
> -
>  	return 0;
>  }


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