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

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Message-ID: <294db5cf-4c95-d56c-0a42-60ca95393c06@gmail.com>
Date:   Fri, 18 Sep 2020 07:49:31 +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

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.