Re: [PATCH v2 5/7] drm/ltdc: Use the panel-bridge helper.

[Archit Taneja <architt@codeaurora.org>]

Hi Boris,

On 05/31/2017 11:56 AM, Boris Brezillon wrote:
> Hi Philippe,
>
> Le Tue, 30 May 2017 16:55:42 +0000,
> Philippe CORNU <philippe.cornu@st.com> a écrit :
>
>> Hi Eric,
>>
>> I took your patch for the panel-bridge and it works perfectly in both
>> DPI mode (panel RGB //) and DSI mode (bridge dw mipi dsi), bravo :-)
>
> I still don't understand how it can work without a call to
> drm_bridge_attach() (which is used to link the RGB encoder to the DPI
> connector). I'm probably missing something obvious. Maybe someone can
> point it out :-).

I think the expectation is that there will be a follow-up patch that
would add bridge support. Philippe had posted a patch for adding bridges
to ltdc before:

https://patchwork.kernel.org/patch/9724835/

He can now redo his patch over Eric's panel-bridge patch-set.

Thanks,
Archit

>
> Thanks,
>
> Boris
>
>>
>> ~160 lines have been removed from ltdc.c thanks to your panel-bridge code!
>>
>> Many thanks
>> Philippe
>>
>> On 05/11/2017 08:31 PM, Eric Anholt wrote:
>>> Another 100 lines of boilerplate gone.  Bridges aren't supported yet,
>>> but will be trivial to add later.
>>>
>>> Signed-off-by: Eric Anholt <eric@anholt.net>
>>> ---
>>>
>>> Also untested.
>>>
>>>   drivers/gpu/drm/stm/ltdc.c | 128 +++++----------------------------------------
>>>   drivers/gpu/drm/stm/ltdc.h |   2 +-
>>>   2 files changed, 13 insertions(+), 117 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
>>> index a40418cda74a..41a1c5d68f5b 100644
>>> --- a/drivers/gpu/drm/stm/ltdc.c
>>> +++ b/drivers/gpu/drm/stm/ltdc.c
>>> @@ -269,11 +269,6 @@ static inline struct ltdc_device *encoder_to_ltdc(struct drm_encoder *enc)
>>>   	return (struct ltdc_device *)enc->dev->dev_private;
>>>   }
>>>
>>> -static inline struct ltdc_device *connector_to_ltdc(struct drm_connector *con)
>>> -{
>>> -	return (struct ltdc_device *)con->dev->dev_private;
>>> -}
>>> -
>>>   static inline enum ltdc_pix_fmt to_ltdc_pixelformat(u32 drm_fmt)
>>>   {
>>>   	enum ltdc_pix_fmt pf;
>>> @@ -815,22 +810,12 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
>>>
>>>   static void ltdc_rgb_encoder_enable(struct drm_encoder *encoder)
>>>   {
>>> -	struct ltdc_device *ldev = encoder_to_ltdc(encoder);
>>> -
>>>   	DRM_DEBUG_DRIVER("\n");
>>> -
>>> -	drm_panel_prepare(ldev->panel);
>>> -	drm_panel_enable(ldev->panel);
>>>   }
>>>
>>>   static void ltdc_rgb_encoder_disable(struct drm_encoder *encoder)
>>>   {
>>> -	struct ltdc_device *ldev = encoder_to_ltdc(encoder);
>>> -
>>>   	DRM_DEBUG_DRIVER("\n");
>>> -
>>> -	drm_panel_disable(ldev->panel);
>>> -	drm_panel_unprepare(ldev->panel);
>>>   }
>>>
>>>   static const struct drm_encoder_helper_funcs ltdc_rgb_encoder_helper_funcs = {
>>> @@ -863,82 +848,6 @@ static struct drm_encoder *ltdc_rgb_encoder_create(struct drm_device *ddev)
>>>   	return encoder;
>>>   }
>>>
>>> -/*
>>> - * DRM_CONNECTOR
>>> - */
>>> -
>>> -static int ltdc_rgb_connector_get_modes(struct drm_connector *connector)
>>> -{
>>> -	struct drm_device *ddev = connector->dev;
>>> -	struct ltdc_device *ldev = ddev->dev_private;
>>> -	int ret = 0;
>>> -
>>> -	DRM_DEBUG_DRIVER("\n");
>>> -
>>> -	if (ldev->panel)
>>> -		ret = drm_panel_get_modes(ldev->panel);
>>> -
>>> -	return ret < 0 ? 0 : ret;
>>> -}
>>> -
>>> -static struct drm_connector_helper_funcs ltdc_rgb_connector_helper_funcs = {
>>> -	.get_modes = ltdc_rgb_connector_get_modes,
>>> -};
>>> -
>>> -static enum drm_connector_status
>>> -ltdc_rgb_connector_detect(struct drm_connector *connector, bool force)
>>> -{
>>> -	struct ltdc_device *ldev = connector_to_ltdc(connector);
>>> -
>>> -	return ldev->panel ? connector_status_connected :
>>> -	       connector_status_disconnected;
>>> -}
>>> -
>>> -static void ltdc_rgb_connector_destroy(struct drm_connector *connector)
>>> -{
>>> -	DRM_DEBUG_DRIVER("\n");
>>> -
>>> -	drm_connector_unregister(connector);
>>> -	drm_connector_cleanup(connector);
>>> -}
>>> -
>>> -static const struct drm_connector_funcs ltdc_rgb_connector_funcs = {
>>> -	.dpms = drm_atomic_helper_connector_dpms,
>>> -	.fill_modes = drm_helper_probe_single_connector_modes,
>>> -	.detect = ltdc_rgb_connector_detect,
>>> -	.destroy = ltdc_rgb_connector_destroy,
>>> -	.reset = drm_atomic_helper_connector_reset,
>>> -	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>>> -	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>>> -};
>>> -
>>> -struct drm_connector *ltdc_rgb_connector_create(struct drm_device *ddev)
>>> -{
>>> -	struct drm_connector *connector;
>>> -	int err;
>>> -
>>> -	connector = devm_kzalloc(ddev->dev, sizeof(*connector), GFP_KERNEL);
>>> -	if (!connector) {
>>> -		DRM_ERROR("Failed to allocate connector\n");
>>> -		return NULL;
>>> -	}
>>> -
>>> -	connector->polled = DRM_CONNECTOR_POLL_HPD;
>>> -
>>> -	err = drm_connector_init(ddev, connector, &ltdc_rgb_connector_funcs,
>>> -				 DRM_MODE_CONNECTOR_DPI);
>>> -	if (err) {
>>> -		DRM_ERROR("Failed to initialize connector\n");
>>> -		return NULL;
>>> -	}
>>> -
>>> -	drm_connector_helper_add(connector, &ltdc_rgb_connector_helper_funcs);
>>> -
>>> -	DRM_DEBUG_DRIVER("RGB connector:%d created\n", connector->base.id);
>>> -
>>> -	return connector;
>>> -}
>>> -
>>>   static int ltdc_get_caps(struct drm_device *ddev)
>>>   {
>>>   	struct ltdc_device *ldev = ddev->dev_private;
>>> @@ -972,7 +881,7 @@ static int ltdc_get_caps(struct drm_device *ddev)
>>>   	return 0;
>>>   }
>>>
>>> -static struct drm_panel *ltdc_get_panel(struct drm_device *ddev)
>>> +static struct drm_bridge *ltdc_get_bridge(struct drm_device *ddev)
>>>   {
>>>   	struct device *dev = ddev->dev;
>>>   	struct device_node *np = dev->of_node;
>>> @@ -1004,7 +913,10 @@ static struct drm_panel *ltdc_get_panel(struct drm_device *ddev)
>>>   		}
>>>   	}
>>>
>>> -	return panel;
>>> +	if (!panel)
>>> +		return ERR_PTR(-ENODEV);
>>> +
>>> +	return drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DPI);
>>>   }
>>>
>>>   int ltdc_load(struct drm_device *ddev)
>>> @@ -1014,7 +926,6 @@ int ltdc_load(struct drm_device *ddev)
>>>   	struct device *dev = ddev->dev;
>>>   	struct device_node *np = dev->of_node;
>>>   	struct drm_encoder *encoder;
>>> -	struct drm_connector *connector = NULL;
>>>   	struct drm_crtc *crtc;
>>>   	struct reset_control *rstc;
>>>   	struct resource res;
>>> @@ -1022,8 +933,8 @@ int ltdc_load(struct drm_device *ddev)
>>>
>>>   	DRM_DEBUG_DRIVER("\n");
>>>
>>> -	ldev->panel = ltdc_get_panel(ddev);
>>> -	if (!ldev->panel)
>>> +	ldev->bridge = ltdc_get_bridge(ddev);
>>> +	if (!ldev->bridge)
>>>   		return -EPROBE_DEFER;
>>>
>>>   	rstc = of_reset_control_get(np, NULL);
>>> @@ -1082,28 +993,13 @@ int ltdc_load(struct drm_device *ddev)
>>>
>>>   	DRM_INFO("ltdc hw version 0x%08x - ready\n", ldev->caps.hw_version);
>>>
>>> -	if (ldev->panel) {
>>> +	if (ldev->bridge) {
>>>   		encoder = ltdc_rgb_encoder_create(ddev);
>>>   		if (!encoder) {
>>>   			DRM_ERROR("Failed to create RGB encoder\n");
>>>   			ret = -EINVAL;
>>>   			goto err;
>>>   		}
>>> -
>>> -		connector = ltdc_rgb_connector_create(ddev);
>>> -		if (!connector) {
>>> -			DRM_ERROR("Failed to create RGB connector\n");
>>> -			ret = -EINVAL;
>>> -			goto err;
>>> -		}
>>> -
>>> -		ret = drm_mode_connector_attach_encoder(connector, encoder);
>>> -		if (ret) {
>>> -			DRM_ERROR("Failed to attach connector to encoder\n");
>>> -			goto err;
>>> -		}
>>> -
>>> -		drm_panel_attach(ldev->panel, connector);
>>>   	}
>>>
>>>   	crtc = devm_kzalloc(dev, sizeof(*crtc), GFP_KERNEL);
>>> @@ -1130,8 +1026,8 @@ int ltdc_load(struct drm_device *ddev)
>>>
>>>   	return 0;
>>>   err:
>>> -	if (ldev->panel)
>>> -		drm_panel_detach(ldev->panel);
>>> +	if (ldev->bridge)
>>> +		drm_panel_bridge_remove(ldev->bridge);
>>>
>>>   	clk_disable_unprepare(ldev->pixel_clk);
>>>
>>> @@ -1146,8 +1042,8 @@ void ltdc_unload(struct drm_device *ddev)
>>>
>>>   	drm_vblank_cleanup(ddev);
>>>
>>> -	if (ldev->panel)
>>> -		drm_panel_detach(ldev->panel);
>>> +	if (ldev->bridge)
>>> +		drm_panel_bridge_remove(ldev->bridge);
>>>
>>>   	clk_disable_unprepare(ldev->pixel_clk);
>>>   }
>>> diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
>>> index d7a9c736ac1e..d78cb0dd3200 100644
>>> --- a/drivers/gpu/drm/stm/ltdc.h
>>> +++ b/drivers/gpu/drm/stm/ltdc.h
>>> @@ -24,7 +24,7 @@ struct ltdc_device {
>>>   	struct drm_fbdev_cma *fbdev;
>>>   	void __iomem *regs;
>>>   	struct clk *pixel_clk;	/* lcd pixel clock */
>>> -	struct drm_panel *panel;
>>> +	struct drm_bridge *bridge;
>>>   	struct mutex err_lock;	/* protecting error_status */
>>>   	struct ltdc_caps caps;
>>>   	u32 clut[256];		/* color look up table */
>>>
>

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