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Message-ID: <24282420-b4dd-45b3-bb1c-fc37fe4a8205@siemens.com>
Date:   Mon, 30 Oct 2023 10:25:11 +0100
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v7 7/8] drm/tidss: Update encoder/bridge chain connect
 model
Content-Language: en-US
To:     Aradhya Bhatia <a-bhatia1@ti.com>,
        Tomi Valkeinen <tomba@kernel.org>,
        Jyri Sarha <jyri.sarha@iki.fi>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Robert Foss <rfoss@kernel.org>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Swapnil Jakhade <sjakhade@cadence.com>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        Francesco Dolcini <francesco@dolcini.it>
Cc:     DRI Development List <dri-devel@lists.freedesktop.org>,
        Linux Kernel List <linux-kernel@vger.kernel.org>,
        Nishanth Menon <nm@ti.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Rahul T R <r-ravikumar@ti.com>,
        Devarsh Thakkar <devarsht@ti.com>,
        Jayesh Choudhary <j-choudhary@ti.com>,
        "Su, Bao Cheng (RC-CN DF FA R&D)" <baocheng.su@siemens.com>
References: <20230606082142.23760-1-a-bhatia1@ti.com>
 <20230606082142.23760-8-a-bhatia1@ti.com>
From:   Jan Kiszka <jan.kiszka@siemens.com>
In-Reply-To: <20230606082142.23760-8-a-bhatia1@ti.com>
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On 06.06.23 10:21, Aradhya Bhatia wrote:
> With the new encoder/bridge chain model, the display controller driver
> is required to create a drm_connector entity instead of asking the
> bridge to do so during drm_bridge_attach. Moreover, the controller
> driver should create a drm_bridge entity to negotiate bus formats and a
> 'simple' drm_encoder entity to expose it to userspace.
> 
> Update the encoder/bridge initialization sequence in tidss as per the
> new model.
> 
> Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
> ---
> 
> Notes:
> 
>     changes from v5:
>     * Drop patches 5 and 6 from the original series.
>     * Instead add this patch that addresses Boris Brezillon's comments
>       of creating bridge, simple encoder and connector.
> 
>  drivers/gpu/drm/tidss/tidss_encoder.c | 140 ++++++++++++++++----------
>  drivers/gpu/drm/tidss/tidss_encoder.h |   5 +-
>  drivers/gpu/drm/tidss/tidss_kms.c     |  12 +--
>  3 files changed, 94 insertions(+), 63 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tidss/tidss_encoder.c b/drivers/gpu/drm/tidss/tidss_encoder.c
> index 0d4865e9c03d..17a86bed8054 100644
> --- a/drivers/gpu/drm/tidss/tidss_encoder.c
> +++ b/drivers/gpu/drm/tidss/tidss_encoder.c
> @@ -6,91 +6,125 @@
>  
>  #include <linux/export.h>
>  
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_bridge_connector.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_modeset_helper_vtables.h>
>  #include <drm/drm_panel.h>
>  #include <drm/drm_of.h>
> +#include <drm/drm_simple_kms_helper.h>
>  
>  #include "tidss_crtc.h"
>  #include "tidss_drv.h"
>  #include "tidss_encoder.h"
>  
> -static int tidss_encoder_atomic_check(struct drm_encoder *encoder,
> -				      struct drm_crtc_state *crtc_state,
> -				      struct drm_connector_state *conn_state)
> +struct tidss_encoder {
> +	struct drm_bridge bridge;
> +	struct drm_encoder encoder;
> +	struct drm_connector *connector;
> +	struct drm_bridge *next_bridge;
> +	struct tidss_device *tidss;
> +};
> +
> +static inline struct tidss_encoder
> +*bridge_to_tidss_encoder(struct drm_bridge *b)
> +{
> +	return container_of(b, struct tidss_encoder, bridge);
> +}
> +
> +static int tidss_bridge_attach(struct drm_bridge *bridge,
> +			       enum drm_bridge_attach_flags flags)
> +{
> +	struct tidss_encoder *t_enc = bridge_to_tidss_encoder(bridge);
> +
> +	return drm_bridge_attach(bridge->encoder, t_enc->next_bridge,
> +				 bridge, flags);
> +}
> +
> +static int tidss_bridge_atomic_check(struct drm_bridge *bridge,
> +				     struct drm_bridge_state *bridge_state,
> +				     struct drm_crtc_state *crtc_state,
> +				     struct drm_connector_state *conn_state)
>  {
> -	struct drm_device *ddev = encoder->dev;
> +	struct tidss_encoder *t_enc = bridge_to_tidss_encoder(bridge);
> +	struct tidss_device *tidss = t_enc->tidss;
>  	struct tidss_crtc_state *tcrtc_state = to_tidss_crtc_state(crtc_state);
>  	struct drm_display_info *di = &conn_state->connector->display_info;
> -	struct drm_bridge *bridge;
> -	bool bus_flags_set = false;
> -
> -	dev_dbg(ddev->dev, "%s\n", __func__);
> -
> -	/*
> -	 * Take the bus_flags from the first bridge that defines
> -	 * bridge timings, or from the connector's display_info if no
> -	 * bridge defines the timings.
> -	 */
> -	drm_for_each_bridge_in_chain(encoder, bridge) {
> -		if (!bridge->timings)
> -			continue;
> -
> -		tcrtc_state->bus_flags = bridge->timings->input_bus_flags;
> -		bus_flags_set = true;
> -		break;
> -	}
> +	struct drm_bridge_state *next_bridge_state = NULL;
> +
> +	if (t_enc->next_bridge)
> +		next_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
> +								    t_enc->next_bridge);
>  
> -	if (!di->bus_formats || di->num_bus_formats == 0)  {
> -		dev_err(ddev->dev, "%s: No bus_formats in connected display\n",
> +	if (next_bridge_state) {
> +		tcrtc_state->bus_flags = next_bridge_state->input_bus_cfg.flags;
> +		tcrtc_state->bus_format = next_bridge_state->input_bus_cfg.format;
> +	} else if (di->num_bus_formats) {
> +		tcrtc_state->bus_format = di->bus_formats[0];
> +		tcrtc_state->bus_flags = di->bus_flags;
> +	} else {
> +		dev_err(tidss->dev, "%s: No bus_formats in connected display\n",
>  			__func__);
>  		return -EINVAL;
>  	}
>  
> -	// XXX any cleaner way to set bus format and flags?
> -	tcrtc_state->bus_format = di->bus_formats[0];
> -	if (!bus_flags_set)
> -		tcrtc_state->bus_flags = di->bus_flags;
> -
>  	return 0;
>  }
>  
> -static void tidss_encoder_destroy(struct drm_encoder *encoder)
> -{
> -	drm_encoder_cleanup(encoder);
> -	kfree(encoder);
> -}
> -
> -static const struct drm_encoder_helper_funcs encoder_helper_funcs = {
> -	.atomic_check = tidss_encoder_atomic_check,
> -};
> -
> -static const struct drm_encoder_funcs encoder_funcs = {
> -	.destroy = tidss_encoder_destroy,
> +static const struct drm_bridge_funcs tidss_bridge_funcs = {
> +	.attach				= tidss_bridge_attach,
> +	.atomic_check			= tidss_bridge_atomic_check,
> +	.atomic_reset			= drm_atomic_helper_bridge_reset,
> +	.atomic_duplicate_state		= drm_atomic_helper_bridge_duplicate_state,
> +	.atomic_destroy_state		= drm_atomic_helper_bridge_destroy_state,
>  };
>  
> -struct drm_encoder *tidss_encoder_create(struct tidss_device *tidss,
> -					 u32 encoder_type, u32 possible_crtcs)
> +int tidss_encoder_create(struct tidss_device *tidss,
> +			 struct drm_bridge *next_bridge,
> +			 u32 encoder_type, u32 possible_crtcs)
>  {
> +	struct tidss_encoder *t_enc;
>  	struct drm_encoder *enc;
> +	struct drm_connector *connector;
>  	int ret;
>  
> -	enc = kzalloc(sizeof(*enc), GFP_KERNEL);
> -	if (!enc)
> -		return ERR_PTR(-ENOMEM);
> +	t_enc = drmm_simple_encoder_alloc(&tidss->ddev, struct tidss_encoder,
> +					  encoder, encoder_type);
> +	if (IS_ERR(t_enc))
> +		return PTR_ERR(t_enc);
> +
> +	t_enc->tidss = tidss;
> +	t_enc->next_bridge = next_bridge;
> +	t_enc->bridge.funcs = &tidss_bridge_funcs;
>  
> +	enc = &t_enc->encoder;
>  	enc->possible_crtcs = possible_crtcs;
>  
> -	ret = drm_encoder_init(&tidss->ddev, enc, &encoder_funcs,
> -			       encoder_type, NULL);
> -	if (ret < 0) {
> -		kfree(enc);
> -		return ERR_PTR(ret);
> +	/* Attaching first bridge to the encoder */
> +	ret = drm_bridge_attach(enc, &t_enc->bridge, NULL,
> +				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +	if (ret) {
> +		dev_err(tidss->dev, "bridge attach failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Initializing the connector at the end of bridge-chain */
> +	connector = drm_bridge_connector_init(&tidss->ddev, enc);
> +	if (IS_ERR(connector)) {
> +		dev_err(tidss->dev, "bridge_connector create failed\n");
> +		return PTR_ERR(connector);
> +	}
> +
> +	ret = drm_connector_attach_encoder(connector, enc);
> +	if (ret) {
> +		dev_err(tidss->dev, "attaching encoder to connector failed\n");
> +		return ret;
>  	}
>  
> -	drm_encoder_helper_add(enc, &encoder_helper_funcs);
> +	t_enc->connector = connector;
>  
>  	dev_dbg(tidss->dev, "Encoder create done\n");
>  
> -	return enc;
> +	return ret;
>  }
> diff --git a/drivers/gpu/drm/tidss/tidss_encoder.h b/drivers/gpu/drm/tidss/tidss_encoder.h
> index ace877c0e0fd..3e561d6b1e83 100644
> --- a/drivers/gpu/drm/tidss/tidss_encoder.h
> +++ b/drivers/gpu/drm/tidss/tidss_encoder.h
> @@ -11,7 +11,8 @@
>  
>  struct tidss_device;
>  
> -struct drm_encoder *tidss_encoder_create(struct tidss_device *tidss,
> -					 u32 encoder_type, u32 possible_crtcs);
> +int tidss_encoder_create(struct tidss_device *tidss,
> +			 struct drm_bridge *next_bridge,
> +			 u32 encoder_type, u32 possible_crtcs);
>  
>  #endif
> diff --git a/drivers/gpu/drm/tidss/tidss_kms.c b/drivers/gpu/drm/tidss/tidss_kms.c
> index ad2fa3c3d4a7..c979ad1af236 100644
> --- a/drivers/gpu/drm/tidss/tidss_kms.c
> +++ b/drivers/gpu/drm/tidss/tidss_kms.c
> @@ -193,7 +193,6 @@ static int tidss_dispc_modeset_init(struct tidss_device *tidss)
>  	for (i = 0; i < num_pipes; ++i) {
>  		struct tidss_plane *tplane;
>  		struct tidss_crtc *tcrtc;
> -		struct drm_encoder *enc;
>  		u32 hw_plane_id = feat->vid_order[tidss->num_planes];
>  		int ret;
>  
> @@ -216,16 +215,13 @@ static int tidss_dispc_modeset_init(struct tidss_device *tidss)
>  
>  		tidss->crtcs[tidss->num_crtcs++] = &tcrtc->crtc;
>  
> -		enc = tidss_encoder_create(tidss, pipes[i].enc_type,
> +		ret = tidss_encoder_create(tidss, pipes[i].bridge,
> +					   pipes[i].enc_type,
>  					   1 << tcrtc->crtc.index);
> -		if (IS_ERR(enc)) {
> +		if (ret) {
>  			dev_err(tidss->dev, "encoder create failed\n");
> -			return PTR_ERR(enc);
> -		}
> -
> -		ret = drm_bridge_attach(enc, pipes[i].bridge, NULL, 0);
> -		if (ret)
>  			return ret;
> +		}
>  	}
>  
>  	/* create overlay planes of the leftover planes */

This breaks the IOT2050 devices over 6.6, just bisected to it:

[    3.435153] [drm] Initialized tidss 1.0.0 20180215 for 4a00000.dss on minor 0
[    3.491246] tidss 4a00000.dss: [drm] Cannot find any crtc or sizes

vs.

[    3.436116] [drm] Initialized tidss 1.0.0 20180215 for 4a00000.dss on minor 0
[    3.910574] Console: switching to colour frame buffer device 80x30
[    3.937614] tidss 4a00000.dss: [drm] fb0: tidssdrmfb frame buffer device

Do we need to adjust its device tree to anything, or what may be the 
reason?

Jan

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