[PATCH V7 03/12] drm/bridge: Add helper functions for drm_bridge

[Ajay kumar]

On Tue, Oct 28, 2014 at 3:31 PM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Tue, Oct 28, 2014 at 10:21 AM, Ajay kumar <ajaynumb at gmail.com> wrote:
>> Hi Daniel and Sean,
>>
>> Thanks for the comments!
>>
>> On Tue, Oct 28, 2014 at 1:28 AM, Sean Paul <seanpaul at chromium.org> wrote:
>>> On Mon, Oct 27, 2014 at 3:01 PM, Daniel Vetter <daniel at ffwll.ch> wrote:
>>>> So don't ask why but I accidentally ended up in a branch looking at this
>>>> patch and didn't like it. So very quick&grumpy review.
>>>>
>>>> First, please make the patch subject more descriptive: I'd expect a helper
>>>> function scaffolding like the various crtc/probe/dp ... helpers we already
>>>> have. You instead add code to untangle the probe ordering. Please say so.
>> Sure. I will reword it properly.
>>
>>>> More comments below.
>>>>
>>>> On Wed, Aug 27, 2014 at 07:59:37PM +0530, Ajay Kumar wrote:
>>>>> A set of helper functions are defined in this patch to make
>>>>> bridge driver probe independent of the drm flow.
>>>>>
>>>>> The bridge devices register themselves on a lookup table
>>>>> when they get probed by calling "drm_bridge_add".
>>>>>
>>>>> The parent encoder driver waits till the bridge is available
>>>>> in the lookup table(by calling "of_drm_find_bridge") and then
>>>>> continues with its initialization.
>>>>>
>>>>> The encoder driver should also call "drm_bridge_attach" to pass
>>>>> on the drm_device, encoder pointers to the bridge object.
>>>>>
>>>>> drm_bridge_attach inturn calls drm_bridge_init to register itself
>>>>> with the drm core. Later, it calls "bridge->funcs->attach" so that
>>>>> bridge can continue with other initializations.
>>>>>
>>>>> Signed-off-by: Ajay Kumar <ajaykumar.rs at samsung.com>
>>>>
>>>> [snip]
>>>>
>>>>> @@ -660,8 +662,11 @@ struct drm_bridge_funcs {
>>>>>   * @driver_private: pointer to the bridge driver's internal context
>>>>>   */
>>>>>  struct drm_bridge {
>>>>> -     struct drm_device *dev;
>>>>> +     struct device *dev;
>>>>
>>>> Please don't rename the ->dev pointer into drm. Because _all_ the other
>>>> drm structures still call it ->dev. Also, can't we use struct device_node
>>>> here like we do in the of helpers Russell added? See 7e435aad38083
>>>>
>>>
>>> I think this is modeled after the naming in drm_panel,
>> Right, The entire rework is based on how drm_panel framework is structured.
>>
>>> FWIW. However,
>>> seems reasonable to keep the device_node instead.
>> Yes, its visible that just device_node would be sufficient.
>> This will save us from renaming drm_device as well.
>>
>>>>> +     struct drm_device *drm;
>>>>> +     struct drm_encoder *encoder;
>>>>
>>>> This breaks bridge->bridge chaining (if we ever get there). It seems
>>>> pretty much unused anyway except for an EBUSY check. Can't you use
>>>> bridge->dev for that?
>>>>
>>>
>>> Yeah, I'd prefer to pass drm_device directly into drm_bridge_attach
>>> and leave it up to the caller to establish the proper chain.
>> Ok. I will use drm_device pointer directly instead of passing encoder pointer.
>
> Hm, if you do this can you pls also update drm_panel accordingly? It
> shouldn't be a lot of fuzz and would make things around drm+dt more
> consistent.
Are you talking about using struct device_node instead of struct device?
I guess you have misplaced the comment under the wrong section!

>>
>>>>>       struct list_head head;
>>>>> +     struct list_head list;
>>>>
>>>> These lists need better names. I know that the "head" is really awful,
>>>> especially since it's actually not the head of the list but just an
>>>> element.
>>>
>>> I think we can just rip bridge_list out of mode_config if we're going
>>> to keep track of bridges elsewhere. So we can nuke "head" and keep
>>> "list". This also means that bridge->destroy() goes away, but that's
>>> probably Ok if everything converts to the standalone driver model
>>> where we have driver->remove()
>>>
>>> Sean
>> Great! Thierry actually mentioned about this once, and we have the
>> confirmation now.
>>
>>>>>
>>>>>       struct drm_mode_object base;
>>>>
>>>>
>>>> Aside: I've noticed all this trying to update the kerneldoc for struct
>>>> drm_bridge, which just showed that this patch makes inconsistent changes.
>>>> Trying to write kerneldoc is a really great way to come up with better
>>>> interfaces imo.
>>>>
>>>> Cheers, Daniel
>> I din't get this actually. You want me to create Doc../drm_bridge.txt
>> or something similar?
>
> If you want to document drm_bridge then I recomment to sprinkle proper
> kerneldoc over drm_bridge.c and pull it all into the drm DocBook
> template. That way all the drm documentation is in one place. I've
> done that for drm_crtc.h in an unrelated patch series (but based upon
> a branch with your patch here included) and there's struct drm_bridge*
> in there. Hence why I've noticed.
Can you send a link for that?
And, is there any problem if the doc comes later?

Ajay