[PATCH 2/3] drm/dp_mst: Expose build_mst_prop_path()

[Li, Sun peng (Leo)]

On 2019-04-24 1:26 p.m., Lyude Paul wrote:
> Closer, but are we sure we want to use the MST prop path for this? Why not add
> a sysfs attribute with the corresponding DRM connector name instead since the
> connector itself will have a path property. That way we can associate aux
> devices for eDP and DP devices with their corresponding connectors as well

I thought about that as well, but I hit a wall when trying to get the
SST connector from the aux device. Perhaps there's a simpler way that
I'm overlooking?

It's easier for MST, since the mst_port can be obtained via container_of
dp_aux. port->connector would then give what we want.

For SST though, each driver calls drm_aux_register() with an aux struct
that they've initialized. I'm not sure how I can reliably get the
drm_connector from that.

Maybe drm_dp_aux should have a back reference to the connector? FWICT
all drivers using drm_aux_register() should be able to provide the
associated connector when calling it.

Leo


> 
> On Mon, 2019-04-22 at 19:56 -0400, sunpeng.li at amd.com wrote:
>> From: Leo Li <sunpeng.li at amd.com>
>>
>> To give identifiable attributes to MST DP aux devices, we can use the
>> MST relative address. Expose this function for later use.
>>
>> Signed-off-by: Leo Li <sunpeng.li at amd.com>
>> ---
>>   drivers/gpu/drm/drm_dp_mst_topology.c | 4 ++--
>>   include/drm/drm_dp_mst_helper.h       | 4 ++++
>>   2 files changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
>> b/drivers/gpu/drm/drm_dp_mst_topology.c
>> index 2ab16c9..86ff8e2 100644
>> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
>> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
>> @@ -1120,7 +1120,7 @@ static void drm_dp_check_mstb_guid(struct
>> drm_dp_mst_branch *mstb, u8 *guid)
>>   	}
>>   }
>>   
>> -static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
>> +void drm_dp_build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
>>   				int pnum,
>>   				char *proppath,
>>   				size_t proppath_size)
>> @@ -1202,7 +1202,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch
>> *mstb,
>>   	if (created && !port->input) {
>>   		char proppath[255];
>>   
>> -		build_mst_prop_path(mstb, port->port_num, proppath,
>> sizeof(proppath));
>> +		drm_dp_build_mst_prop_path(mstb, port->port_num, proppath,
>> sizeof(proppath));
>>   		port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr,
>> port, proppath);
>>   		if (!port->connector) {
>>   			/* remove it from the port list */
>> diff --git a/include/drm/drm_dp_mst_helper.h
>> b/include/drm/drm_dp_mst_helper.h
>> index 371cc28..81c8d79 100644
>> --- a/include/drm/drm_dp_mst_helper.h
>> +++ b/include/drm/drm_dp_mst_helper.h
>> @@ -602,6 +602,10 @@ void drm_dp_mst_deallocate_vcpi(struct
>> drm_dp_mst_topology_mgr *mgr,
>>   int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
>>   			   int pbn);
>>   
>> +void drm_dp_build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
>> +				   int pnum,
>> +				   char *proppath,
>> +				   size_t proppath_size);
>>   
>>   int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr);
>>