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Message-ID: <e387cc1a-2cf6-ee0f-78fa-82d327b289b4@ti.com>
Date:   Tue, 31 Oct 2023 01:08:43 +0530
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Subject: Re: [PATCH v7 7/8] drm/tidss: Update encoder/bridge chain connect
 model
Content-Language: en-US
To:     Jan Kiszka <jan.kiszka@siemens.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>
 <24282420-b4dd-45b3-bb1c-fc37fe4a8205@siemens.com>
From:   Aradhya Bhatia <a-bhatia1@ti.com>
In-Reply-To: <24282420-b4dd-45b3-bb1c-fc37fe4a8205@siemens.com>
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Precedence: bulk


On 30-Oct-23 14:55, Jan Kiszka wrote:
> 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?
> 

Hey Jan,

This patch series added support for the DRM_BRIDGE_ATTACH_NO_CONNECTOR
flag, for tidss, and for a few of the bridges.

Upon a quick look at the devicetree files, I see that the IOT-2050
platform is using Toshiba's TC358767 DPI to DP bridge, and it appears
that the TC358767 driver does not support the get_input_bus_fmt hook.

I have sent a patch for it[0].

Since I do not have hardware with me, I would appreciate it if you could
test and review it. The patch has only been build tested.


Regards
Aradhya


[0]: Patch Link:
https://lore.kernel.org/all/20231030192846.27934-1-a-bhatia1@ti.com/