linux-kernel - Re: [PATCH v2] software_node: Add support for fwnode

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Date:   Fri, 18 Sep 2020 08:46:52 +0100
From:   Dan Scally <djrscally@...il.com>
To:     Sakari Ailus <sakari.ailus@....fi>
Cc:     gregkh@...uxfoundation.org, rafael@...nel.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        heikki.krogerus@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
        kieran.bingham@...asonboard.com, jorhand@...ux.microsoft.com,
        kitakar@...il.com
Subject: Re: [PATCH v2] software_node: Add support for fwnode_graph*() family
 of functions

On 18/09/2020 08:34, Sakari Ailus wrote:
> On Fri, Sep 18, 2020 at 07:49:31AM +0100, Dan Scally wrote:
>> Good morning
>>
>> On 18/09/2020 07:22, Sakari Ailus wrote:
>>> Hi Dan,
>>>
>>> On Wed, Sep 16, 2020 at 02:22:10PM +0100, Dan Scally wrote:
>>>> Hi Sakari - thanks for the comments
>>>>
>>>> On 16/09/2020 10:17, Sakari Ailus wrote:
>>>>> Moi Daniel and Heikki,
>>>>>
>>>>> On Wed, Sep 16, 2020 at 12:28:27AM +0100, Daniel Scally wrote:
>>>>>> From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
>>>>>>
>>>>>> This implements the remaining .graph_* callbacks in the
>>>>>> fwnode operations vector for the software nodes. That makes
>>>>>> the fwnode_graph*() functions available in the drivers also
>>>>>> when software nodes are used.
>>>>>>
>>>>>> The implementation tries to mimic the "OF graph" as much as
>>>>>> possible, but there is no support for the "reg" device
>>>>>> property. The ports will need to have the index in their
>>>>>> name which starts with "port" (for example "port0", "port1",
>>>>>> ...) and endpoints will use the index of the software node
>>>>>> that is given to them during creation. The port nodes can
>>>>>> also be grouped under a specially named "ports" subnode,
>>>>>> just like in DT, if necessary.
>>>>>>
>>>>>> The remote-endpoints are reference properties under the
>>>>>> endpoint nodes that are named "remote-endpoint". 
>>>>>>
>>>>>> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
>>>>>> Co-developed-by: Daniel Scally <djrscally@...il.com>
>>>>>> Signed-off-by: Daniel Scally <djrscally@...il.com>
>>>>>> ---
>>>>>> changes in v2:
>>>>>> 	- added software_node_device_is_available
>>>>>> 	- altered software_node_get_next_child to get references
>>>>>> 	- altered software_node_get_next_endpoint to release references
>>>>>> 	to ports and avoid passing invalid combinations of swnodes to
>>>>>> 	software_node_get_next_child
>>>>>> 	- altered swnode_graph_find_next_port to release port rather than
>>>>>> 	old
>>>>>> 	
>>>>>>  drivers/base/swnode.c | 129 +++++++++++++++++++++++++++++++++++++++++-
>>>>>>  1 file changed, 127 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
>>>>>> index 010828fc785b..d69034b807e3 100644
>>>>>> --- a/drivers/base/swnode.c
>>>>>> +++ b/drivers/base/swnode.c
>>>>>> @@ -363,6 +363,11 @@ static void software_node_put(struct fwnode_handle *fwnode)
>>>>>>  	kobject_put(&swnode->kobj);
>>>>>>  }
>>>>>>  
>>>>>> +static bool software_node_device_is_available(const struct fwnode_handle *fwnode)
>>>>>> +{
>>>>>> +	return is_software_node(fwnode);
>>>>> This basically tells whether the device is there. Are there software node
>>>>> based devices, i.e. do you need this?
>>>>>
>>>>> If you do really need this, then I guess this could just return true for
>>>>> now as if you somehow get here, the node is a software node anyway.
>>>> I do think its better to include it; I'm targeting using this with
>>>> ipu3-cio2; the cio2_parse_firmware() call there doesn't pass
>>>> FWNODE_GRAPH_DEVICE_DISABLED to fwnode_graph_get_endpoint_by_id() so
>>> I wonder if this has something to do with replacing the device's fwnode
>>> in the cio2-bridge patch.
>>>
>>> It's the device that needs to be enabled, and it's not a software node.
>>>
>> I think it is because of that yes, but I don't see a way around it at
>> the moment - unless there's a way to attach the software_node port and
>> endpoints that cio2-bridge creates to the device's existing firmware
>> instead.
> I thought this was how it was meant to be used?
>
> The secondary field is there for this purpose. But it may be not all fwnode
> interface functions operate on fwnode->secondary?
Let me test it; it might just require some changes to
software_node_graph_get_port_parent() to check if the parent fwnode is a
secondary, and if it is to return the primary instead.