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

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Message-ID: <20200918073433.GR834@valkosipuli.retiisi.org.uk>
Date:   Fri, 18 Sep 2020 10:34:33 +0300
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Dan Scally <djrscally@...il.com>
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 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?

-- 
Regards,

Sakari Ailus