[PATCH v4 2/3] drm/tegra: output: Support DRM bridges

[Dmitry Osipenko]

17.04.2020 23:31, Laurent Pinchart пишет:
> Hi Dmitry,
> 
> On Fri, Apr 17, 2020 at 10:41:59PM +0300, Dmitry Osipenko wrote:
>> 17.04.2020 22:30, Laurent Pinchart пишет:
>> ...
>>>>  #include <drm/drm_atomic.h>
>>>> +#include <drm/drm_bridge.h>
>>>
>>> You could add a forward declaration of struct drm_bridge instead, that
>>> can lower the compilation time a little bit.
>>
>> This include is not only for the struct, but also for the
>> drm_bridge_attach(). It looks to me that it should be nicer to keep the
>> include here.
> 
> drm_bridge_attach() is called from .c files. In the .h file you can use
> a forward declaration. It's entirely up to you, but as a general rule, I
> personally try to use forward structure declarations in .h files as much
> as possible.

The current Tegra DRM code is a bit inconsistent in regards to having
forward declarations, it doesn't have them more than have.

I'll add a forward declaration if there will be need to make a v5, ok?

>> ...
>>>> +	port = of_get_child_by_name(output->of_node, "port");
>>>
>>> Do you need to check for the presence of a port node first ? Can you
>>> just check the return value of drm_of_find_panel_or_bridge(), and fall
>>> back to "nvidia,panel" if it returns -ENODEV ?
>>
>> Without the check, the drm_of_find_panel_or_bridge() prints a very noisy
>> error message about missing port node for every output that doesn't have
>> a graph specified in a device-tree (HDMI, DSI and etc).
>>
>> https://elixir.bootlin.com/linux/v5.7-rc1/source/drivers/of/property.c#L621
> 
> Ah yes indeed. That's not very nice.
> 

Please let me know if you'll have a better idea about how this could be
handled.