Re: [RFC V2 1/3] drm: implement chaining of drm bridges

On Tue, May 6, 2014 at 12:45 PM, Ajay kumar ajaynumb@gmail.com wrote:

Sean,

On Tue, May 6, 2014 at 9:25 PM, Sean Paul seanpaul@chromium.org wrote:

...

On Mon, May 5, 2014 at 12:52 PM, Ajay Kumar ajaykumar.rs@samsung.com wrote:

...

As of now, we can have only one bridge hanging off the encoder. With this patch, we allow multiple bridges to hang onto the same encoder with the use of a simple next_bridge ptr.

The drm core calls bridge->funcs for the first bridge which is attached to it, and its upto the individual bridge drivers to call bridge->funcs for the next bridge in the chain.

Signed-off-by: Ajay Kumar ajaykumar.rs@samsung.com

drivers/gpu/drm/drm_crtc.c | 13 ++++++++++++- include/drm/drm_crtc.h | 2 ++ 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index d8b7099..fe9905f 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -918,8 +918,10 @@ EXPORT_SYMBOL(drm_connector_unplug_all);

• Zero on success, error code on failure.

*/ int drm_bridge_init(struct drm_device *dev, struct drm_bridge *bridge,

•           const struct drm_bridge_funcs *funcs)
  

•                   struct drm_encoder *encoder,
  

•                   const struct drm_bridge_funcs *funcs)
  

IMO, we should let whoever is spawning the bridges chain them together, instead of passing encoder in init().

For this, we have to modify drm_bridge_init to return a bridge pointer

Sorry, I don't follow this. You are passing in the bridge pointer, so presumably you already have it.

Sean

and then, as Rob is suggesting, we can have some helper functions to update next_bridge ptr to form a bridge chain, and these functions can be called from the corresponding encoder implementation.

Ajay

...

...

{

•   struct drm_bridge *temp;
    int ret;
  
    drm_modeset_lock_all(dev);
  

@@ -931,6 +933,15 @@ int drm_bridge_init(struct drm_device *dev, struct drm_bridge *bridge, bridge->dev = dev; bridge->funcs = funcs;

•   if (encoder->bridge) {
  

•           temp = encoder->bridge;
  

•           while (temp->next_bridge)
  

•                   temp = temp->next_bridge;
  

•           temp->next_bridge = bridge;
  

•   } else
  

•           encoder->bridge = bridge;
  

•   list_add_tail(&bridge->head, &dev->mode_config.bridge_list);
    dev->mode_config.num_bridge++;
  
  

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index e55fccb..bb6ed88 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -619,6 +619,7 @@ struct drm_bridge_funcs { struct drm_bridge { struct drm_device *dev; struct list_head head;

•   struct drm_bridge *next_bridge;
  
    struct drm_mode_object base;
  
  

@@ -862,6 +863,7 @@ extern void drm_connector_cleanup(struct drm_connector *connector); extern void drm_connector_unplug_all(struct drm_device *dev);

extern int drm_bridge_init(struct drm_device *dev, struct drm_bridge *bridge,

•                      struct drm_encoder *encoder,
                       const struct drm_bridge_funcs *funcs);
  

extern void drm_bridge_cleanup(struct drm_bridge *bridge);

-- 1.8.1.2