Re: [PATCH 1/2] drm: exynos: dsi: Convert to bridge driver

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 22.11.2021 08:06, Jagan Teki wrote:
> Some display panels would come up with a non-DSI output, those
> can have an option to connect the DSI host by means of interface
> bridge converter.
>
> This DSI to non-DSI interface bridge converter would requires
> DSI Host to handle drm bridge functionalities in order to DSI
> Host to Interface bridge.
>
> This patch convert the existing to a drm bridge driver with a
> built-in encoder support for compatibility with existing
> component drivers.
>
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> Note:
> Hi Marek Szyprowski,
>
> Please test this on Panel and Bridge hardware.

I don't have good news, t crashes:

[drm] Exynos DRM: using 13800000.decon device for DMA mapping operations
exynos-drm exynos-drm: bound 13800000.decon (ops decon_component_ops)
exynos-drm exynos-drm: bound 13880000.decon (ops decon_component_ops)
exynos-drm exynos-drm: bound 13930000.mic (ops exynos_mic_component_ops)
[drm:drm_bridge_attach] *ERROR* failed to attach bridge 
/soc@0/dsi@13900000 to encoder TMDS-67: -22
exynos-drm exynos-drm: failed to bind 13900000.dsi (ops 
exynos_dsi_component_ops): -22
Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP
Modules linked in:
CPU: 2 PID: 74 Comm: kworker/u16:1 Not tainted 5.16.0-rc1+ #4141
Hardware name: Samsung TM2E board (DT)
Workqueue: events_unbound deferred_probe_work_func
pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : decon_atomic_disable+0x58/0xd4
lr : decon_atomic_disable+0x28/0xd4
sp : ffff80001390b940
x29: ffff80001390b940 x28: ffff80001259a000 x27: ffff000027f39e80
input: stmfts as 
/devices/platform/soc@0/14ed0000.hsi2c/i2c-3/3-0049/input/input0
x26: 00000000ffffffea x25: ffff000025a40280 x24: 0000000000000001
x23: ffff800011b55f98 x22: ffff0000315dc000 x21: ffff00002695d100
x20: ffff000027e7a080 x19: ffff0000315e6000 x18: 0000000000000000
x17: 645f736f6e797865 x16: 2073706f28206973 x15: 0000000000028ee0
x14: 0000000000000028 x13: 0000000000000001 x12: 0000000000000040
x11: ffff000023c18920 x10: ffff000023c18922 x9 : ffff8000126352f0
x8 : ffff000023c00270 x7 : 0000000000000000 x6 : ffff000023c00268
x5 : ffff000027e7a3a0 x4 : 0000000000000001 x3 : ffff000027e7a080
x2 : 0000000000000024 x1 : ffff800013bc8024 x0 : ffff0000246117c0
Call trace:
  decon_atomic_disable+0x58/0xd4
  decon_unbind+0x1c/0x3c
  component_unbind+0x38/0x60
  component_bind_all+0x16c/0x25c
  exynos_drm_bind+0x104/0x1bc
  try_to_bring_up_master+0x164/0x1d0
  __component_add+0xa8/0x174
  component_add+0x14/0x20
  hdmi_probe+0x438/0x710
  platform_probe+0x68/0xe0
  really_probe.part.0+0x9c/0x31c
  __driver_probe_device+0x98/0x144
  driver_probe_device+0xc8/0x160
  __device_attach_driver+0xb8/0x120
  bus_for_each_drv+0x78/0xd0
  __device_attach+0xd8/0x180
  device_initial_probe+0x14/0x20
  bus_probe_device+0x9c/0xa4
  deferred_probe_work_func+0x88/0xc4
  process_one_work+0x288/0x6f0
  worker_thread+0x74/0x470
  kthread+0x188/0x194
  ret_from_fork+0x10/0x20
Code: 11002042 f9481c61 531e7442 8b020021 (88dffc21)
---[ end trace d73aff585b108954 ]---
Kernel panic - not syncing: synchronous external abort: Fatal exception
SMP: stopping secondary CPUs
Kernel Offset: disabled
CPU features: 0x2,300071c2,00000846
Memory Limit: none
---[ end Kernel panic - not syncing: synchronous external abort: Fatal 
exception ]---

I will try to debug it a bit more once I find some spare time. I've 
applied only the first patch.

>   drivers/gpu/drm/exynos/exynos_drm_dsi.c | 73 +++++++++++++++++--------
>   1 file changed, 51 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 8d137857818c..174590f543c3 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -257,6 +257,7 @@ struct exynos_dsi {
>   	struct drm_connector connector;
>   	struct drm_panel *panel;
>   	struct list_head bridge_chain;
> +	struct drm_bridge bridge;
>   	struct drm_bridge *out_bridge;
>   	struct device *dev;
>   
> @@ -287,9 +288,9 @@ struct exynos_dsi {
>   #define host_to_dsi(host) container_of(host, struct exynos_dsi, dsi_host)
>   #define connector_to_dsi(c) container_of(c, struct exynos_dsi, connector)
>   
> -static inline struct exynos_dsi *encoder_to_dsi(struct drm_encoder *e)
> +static inline struct exynos_dsi *bridge_to_dsi(struct drm_bridge *b)
>   {
> -	return container_of(e, struct exynos_dsi, encoder);
> +	return container_of(b, struct exynos_dsi, bridge);
>   }
>   
>   enum reg_idx {
> @@ -1374,9 +1375,10 @@ static void exynos_dsi_unregister_te_irq(struct exynos_dsi *dsi)
>   	}
>   }
>   
> -static void exynos_dsi_enable(struct drm_encoder *encoder)
> +static void exynos_dsi_atomic_enable(struct drm_bridge *bridge,
> +				     struct drm_bridge_state *old_bridge_state)
>   {
> -	struct exynos_dsi *dsi = encoder_to_dsi(encoder);
> +	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
>   	struct drm_bridge *iter;
>   	int ret;
>   
> @@ -1399,7 +1401,8 @@ static void exynos_dsi_enable(struct drm_encoder *encoder)
>   		list_for_each_entry_reverse(iter, &dsi->bridge_chain,
>   					    chain_node) {
>   			if (iter->funcs->pre_enable)
> -				iter->funcs->pre_enable(iter);
> +				iter->funcs->atomic_pre_enable(iter,
> +							       old_bridge_state);
>   		}
>   	}
>   
> @@ -1413,7 +1416,7 @@ static void exynos_dsi_enable(struct drm_encoder *encoder)
>   	} else {
>   		list_for_each_entry(iter, &dsi->bridge_chain, chain_node) {
>   			if (iter->funcs->enable)
> -				iter->funcs->enable(iter);
> +				iter->funcs->atomic_enable(iter, old_bridge_state);
>   		}
>   	}
>   
> @@ -1429,9 +1432,10 @@ static void exynos_dsi_enable(struct drm_encoder *encoder)
>   	pm_runtime_put(dsi->dev);
>   }
>   
> -static void exynos_dsi_disable(struct drm_encoder *encoder)
> +static void exynos_dsi_atomic_disable(struct drm_bridge *bridge,
> +				      struct drm_bridge_state *old_bridge_state)
>   {
> -	struct exynos_dsi *dsi = encoder_to_dsi(encoder);
> +	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
>   	struct drm_bridge *iter;
>   
>   	if (!(dsi->state & DSIM_STATE_ENABLED))
> @@ -1443,7 +1447,7 @@ static void exynos_dsi_disable(struct drm_encoder *encoder)
>   
>   	list_for_each_entry_reverse(iter, &dsi->bridge_chain, chain_node) {
>   		if (iter->funcs->disable)
> -			iter->funcs->disable(iter);
> +			iter->funcs->atomic_disable(iter, old_bridge_state);
>   	}
>   
>   	exynos_dsi_set_display_enable(dsi, false);
> @@ -1451,7 +1455,7 @@ static void exynos_dsi_disable(struct drm_encoder *encoder)
>   
>   	list_for_each_entry(iter, &dsi->bridge_chain, chain_node) {
>   		if (iter->funcs->post_disable)
> -			iter->funcs->post_disable(iter);
> +			iter->funcs->atomic_post_disable(iter, old_bridge_state);
>   	}
>   
>   	dsi->state &= ~DSIM_STATE_ENABLED;
> @@ -1494,9 +1498,9 @@ static const struct drm_connector_helper_funcs exynos_dsi_connector_helper_funcs
>   	.get_modes = exynos_dsi_get_modes,
>   };
>   
> -static int exynos_dsi_create_connector(struct drm_encoder *encoder)
> +static int exynos_dsi_create_connector(struct exynos_dsi *dsi)
>   {
> -	struct exynos_dsi *dsi = encoder_to_dsi(encoder);
> +	struct drm_encoder *encoder = &dsi->encoder;
>   	struct drm_connector *connector = &dsi->connector;
>   	struct drm_device *drm = encoder->dev;
>   	int ret;
> @@ -1522,9 +1526,21 @@ static int exynos_dsi_create_connector(struct drm_encoder *encoder)
>   	return 0;
>   }
>   
> -static const struct drm_encoder_helper_funcs exynos_dsi_encoder_helper_funcs = {
> -	.enable = exynos_dsi_enable,
> -	.disable = exynos_dsi_disable,
> +static int exynos_dsi_attach(struct drm_bridge *bridge,
> +			     enum drm_bridge_attach_flags flags)
> +{
> +	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
> +
> +	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, NULL, 0);
> +}
> +
> +static const struct drm_bridge_funcs exynos_dsi_bridge_funcs = {
> +	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
> +	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
> +	.atomic_reset		= drm_atomic_helper_bridge_reset,
> +	.atomic_enable		= exynos_dsi_atomic_enable,
> +	.atomic_disable		= exynos_dsi_atomic_disable,
> +	.attach			= exynos_dsi_attach,
>   };
>   
>   MODULE_DEVICE_TABLE(of, exynos_dsi_of_match);
> @@ -1543,7 +1559,7 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>   		dsi->out_bridge = out_bridge;
>   		list_splice_init(&encoder->bridge_chain, &dsi->bridge_chain);
>   	} else {
> -		int ret = exynos_dsi_create_connector(encoder);
> +		int ret = exynos_dsi_create_connector(dsi);
>   
>   		if (ret) {
>   			DRM_DEV_ERROR(dsi->dev,
> @@ -1596,7 +1612,7 @@ static int exynos_dsi_host_detach(struct mipi_dsi_host *host,
>   
>   	if (dsi->panel) {
>   		mutex_lock(&drm->mode_config.mutex);
> -		exynos_dsi_disable(&dsi->encoder);
> +		exynos_dsi_atomic_disable(&dsi->bridge, NULL);
>   		dsi->panel = NULL;
>   		dsi->connector.status = connector_status_disconnected;
>   		mutex_unlock(&drm->mode_config.mutex);
> @@ -1702,12 +1718,16 @@ static int exynos_dsi_bind(struct device *dev, struct device *master,
>   
>   	drm_simple_encoder_init(drm_dev, encoder, DRM_MODE_ENCODER_TMDS);
>   
> -	drm_encoder_helper_add(encoder, &exynos_dsi_encoder_helper_funcs);
> -
>   	ret = exynos_drm_set_possible_crtcs(encoder, EXYNOS_DISPLAY_TYPE_LCD);
>   	if (ret < 0)
>   		return ret;
>   
> +	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, 0);
> +	if (ret) {
> +		drm_encoder_cleanup(&dsi->encoder);
> +		return ret;
> +	}
> +
>   	in_bridge_node = of_graph_get_remote_node(dev->of_node, DSI_PORT_IN, 0);
>   	if (in_bridge_node) {
>   		in_bridge = of_drm_find_bridge(in_bridge_node);
> @@ -1723,10 +1743,9 @@ static void exynos_dsi_unbind(struct device *dev, struct device *master,
>   				void *data)
>   {
>   	struct exynos_dsi *dsi = dev_get_drvdata(dev);
> -	struct drm_encoder *encoder = &dsi->encoder;
> -
> -	exynos_dsi_disable(encoder);
>   
> +	exynos_dsi_atomic_disable(&dsi->bridge, NULL);
> +	drm_encoder_cleanup(&dsi->encoder);
>   	mipi_dsi_host_unregister(&dsi->dsi_host);
>   }
>   
> @@ -1819,6 +1838,12 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>   
>   	pm_runtime_enable(dev);
>   
> +	dsi->bridge.funcs = &exynos_dsi_bridge_funcs;
> +	dsi->bridge.of_node = dev->of_node;
> +	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
> +
> +	drm_bridge_add(&dsi->bridge);
> +
>   	ret = component_add(dev, &exynos_dsi_component_ops);
>   	if (ret)
>   		goto err_disable_runtime;
> @@ -1833,6 +1858,10 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>   
>   static int exynos_dsi_remove(struct platform_device *pdev)
>   {
> +	struct exynos_dsi *dsi = platform_get_drvdata(pdev);
> +
> +	drm_bridge_remove(&dsi->bridge);
> +
>   	pm_runtime_disable(&pdev->dev);
>   
>   	component_del(&pdev->dev, &exynos_dsi_component_ops);

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland