Re: [PATCH v5 4/6] usb: roles: add API to get usb_role_switch by node

[Chunfeng Yun <chunfeng.yun@mediatek.com>]

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Hi Heikki,
On Wed, 2019-05-22 at 17:26 +0300, Heikki Krogerus wrote:
> On Wed, May 22, 2019 at 10:55:17AM +0000, Biju Das wrote:
> > Hi Chunfeng Yun,
> > 
> > Thanks for the feedback.
> > 
> > > Subject: RE: [PATCH v5 4/6] usb: roles: add API to get usb_role_switch by
> > > node
> > > 
> > > Hi Biju,
> > > On Wed, 2019-05-22 at 08:05 +0000, Biju Das wrote:
> > > > Hi Heikki,
> > > >
> > > > Thanks for the feedback.
> > > >
> > > > > Subject: Re: [PATCH v5 4/6] usb: roles: add API to get
> > > > > usb_role_switch by node
> > > > >
> > > > > On Mon, May 20, 2019 at 09:45:46AM +0000, Biju Das wrote:
> > > > > >
> > > > > >
> > > > > > Hi Heikki,
> > > > > >
> > > > > > Thanks for the feedback.
> > > > > >
> > > > > > > Subject: Re: [PATCH v5 4/6] usb: roles: add API to get
> > > > > > > usb_role_switch by node
> > > > > > >
> > > > > > > On Mon, May 20, 2019 at 08:06:41AM +0000, Biju Das wrote:
> > > > > > > > Hi Heikki,
> > > > > > > >
> > > > > > > > > Subject: Re: [PATCH v5 4/6] usb: roles: add API to get
> > > > > > > > > usb_role_switch by node
> > > > > > > > >
> > > > > > > > > On Mon, May 20, 2019 at 10:39:11AM +0800, Chunfeng Yun wrote:
> > > > > > > > > > Hi,
> > > > > > > > > > On Fri, 2019-05-17 at 16:05 +0300, Heikki Krogerus wrote:
> > > > > > > > > > > Hi,
> > > > > > > > > > >
> > > > > > > > > > > On Fri, May 17, 2019 at 01:37:36PM +0300, Heikki Krogerus
> > > wrote:
> > > > > > > > > > > > On Tue, May 14, 2019 at 04:47:21PM +0800, Chunfeng Yun
> > > > > wrote:
> > > > > > > > > > > > > Add fwnode_usb_role_switch_get() to make easier to
> > > > > > > > > > > > > get usb_role_switch by fwnode which register it.
> > > > > > > > > > > > > It's useful when there is not device_connection
> > > > > > > > > > > > > registered between two drivers and only knows the
> > > > > > > > > > > > > fwnode which register usb_role_switch.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Signed-off-by: Chunfeng Yun
> > > > > > > > > > > > > <chunfeng.yun@mediatek.com>
> > > > > > > > > > > > > Tested-by: Biju Das <biju.das@bp.renesas.com>
> > > > > > > > > > > >
> > > > > > > > > > > > Acked-by: Heikki Krogerus
> > > > > > > > > > > > <heikki.krogerus@linux.intel.com>
> > > > > > > > > > >
> > > > > > > > > > > Hold on. I just noticed Rob's comment on patch 2/6,
> > > > > > > > > > > where he points out that you don't need to use device
> > > > > > > > > > > graph since the controller is the parent of the
> > > > > > > > > > > connector. Doesn't that mean you don't really need this API?
> > > > > > > > > > No, I still need it.
> > > > > > > > > > The change is about the way how to get fwnode; when use
> > > > > > > > > > device graph, get fwnode by of_graph_get_remote_node();
> > > > > > > > > > but now will get fwnode by of_get_parent();
> > > > > > > > >
> > > > > > > > > OK, I get that, but I'm still not convinced about if
> > > > > > > > > something like this function is needed at all. I also have
> > > > > > > > > concerns regarding how you are using the function. I'll
> > > > > > > > > explain in comment to the patch 5/6 in this
> > > > > > > series...
> > > > > > > >
> > > > > > > > FYI, Currently  I am also using this api in my patch series.
> > > > > > > > https://patchwork.kernel.org/patch/10944637/
> > > > > > >
> > > > > > > Yes, and I have the same question for you I jusb asked in
> > > > > > > comment I added to the patch 5/6 of this series. Why isn't
> > > > > > > usb_role_switch_get()
> > > > > enough?
> > > > > >
> > > > > > Currently no issue. It will work with this api as well, since the
> > > > > > port node is
> > > > > part of controller node.
> > > > > > For eg:-
> > > > > > https://patchwork.kernel.org/patch/10944627/
> > > > > >
> > > > > > However if any one adds port node inside the connector node, then
> > > > > > this
> > > > > api may won't work as expected.
> > > > > > Currently I get below error
> > > > > >
> > > > > > [    2.299703] OF: graph: no port node found in
> > > > > /soc/i2c@e6500000/hd3ss3220@47
> > > > >
> > > > > We need to understand why is that happening?
> > > > >
> > > >
> > > > Form the stack trace  the parent node is "parent_node=hd3ss3220@47" ,
> > > instead of the "connector" node.
> > > > That is the reason for the above error.
> > > >
> > > > [    2.442429]  of_graph_get_next_endpoint.part.0+0x28/0x168
> > > > [    2.447889]  of_fwnode_graph_get_next_endpoint+0x5c/0xb0
> > > > [    2.453267]  fwnode_graph_get_next_endpoint+0x20/0x30
> > > > [    2.458374]  device_connection_find_match+0x74/0x1a0
> > > > [    2.463399]  usb_role_switch_get+0x20/0x28
> > > > [    2.467542]  hd3ss3220_probe+0xc4/0x218
> > > >
> > > > The use case is
> > > >
> > > > &i2c0 {
> > > > 	hd3ss3220@47 {
> > > >                  	compatible = "ti,hd3ss3220";
> > > >
> > > >                  	usb_con: connector {
> > > >                           		compatible = "usb-c-connector";
> > > >                          		port {
> > > >                                 		 hd3ss3220_ep: endpoint {
> > > >                                         			remote-endpoint =
> > > <&usb3_role_switch>;
> > > >                                 		};
> > > >                          		};
> > > >                 	 };
> > > > 	 };
> > > > };
> > > >
> > > > &usb3_peri0 {
> > > >          companion = <&xhci0>;
> > > >          usb-role-switch;
> > > >
> > > >          port {
> > > >                 usb3_role_switch: endpoint {
> > > >                         remote-endpoint = <&hd3ss3220_ep>;
> > > >                  };
> > > >          };
> > > > };
> > > >
> > > > Q1) How do we modify the usb_role_switch_get() function to search
> > > > Child(connector) and child's endpoint?
> > > How about firstly finding connector node in fwnode_graph_devcon_match(),
> > > then search each endpoint?
> > 
> >  I have done a quick prototyping with the changes you suggested and it works.
> > 
> > -       struct fwnode_handle *ep;
> > +       struct fwnode_handle *ep,*child,*tmp = fwnode; 
> >  
> > -       fwnode_graph_for_each_endpoint(fwnode, ep) {
> > +       child = fwnode_get_named_child_node(fwnode, "connector");
> > +       if (child)
> > +               tmp = child;
> > +
> > +       fwnode_graph_for_each_endpoint(tmp, ep) {
> > 
> > Form the stack trace  the parent node is "parent_node= connector" .
> > 
> > [    2.440922]  of_graph_get_next_endpoint.part.0+0x28/0x168
> > [    2.446381]  of_fwnode_graph_get_next_endpoint+0x5c/0xb0
> > [    2.451758]  fwnode_graph_get_next_endpoint+0x20/0x30
> > [    2.456866]  device_connection_find_match+0x84/0x1c0
> > [    2.461888]  usb_role_switch_get+0x20/0x28
> > 
> > Heikki, 
> > Are you ok  with the above changes?
> 
> Doesn't that mean that if we made fwnode_usb_role_switch_get() the way
> I proposed, there is no problem? You just find the "connector" child
> node in your driver, and pass that to fwnode_usb_role_switch_get():
> 
>         struct fwnode_handle *connector;
>         ...
>         connector = device_get_named_child_node(&client->dev, "connector");
>         if (IS_ERR(connector))
>                 <do something>
> 
>         hd3ss3220->role_sw = fwnode_usb_role_switch_get(connector);
>         ...
> 
> The difference is that instead of just converting a device node of an
> usb role switch to the usb role switch, it works just like
> usb_role_switch_get(), just taking fwnode instead of device entry as
> parameter.
> 
> I prepared the patches implementing fwnode_usb_role_switch_get() the
> way I though it needs to work for my own tests. Please find the
> patches attached.
I tested these patches, it didn't work for case as following:

case 2:

&mtu3 {
    usb-role-switch;

    connector {
        compatible = "linux,typeb-conn-gpio", "usb-b-connector";
        label = "micro-USB";
        type = "micro";
        id-gpios = <&pio 12 GPIO_ACTIVE_HIGH>;
        vbus-supply = <&usb_p0_vbus>;
    };
};

so I consider this case in the function fwnode_graph_devcon_match()
(based on your patches)

diff --git a/drivers/base/devcon.c b/drivers/base/devcon.c
index 8311b70..1dae8b7 100644
--- a/drivers/base/devcon.c
+++ b/drivers/base/devcon.c
@@ -18,9 +18,11 @@
 {
        struct device_connection con = { .id = con_id };
        struct fwnode_handle *ep;
+       int ep_count = 0;
        void *ret;
 
        fwnode_graph_for_each_endpoint(fwnode, ep) {
+               ep_count++;
                con.fwnode = fwnode_graph_get_remote_port_parent(ep);
                if (!fwnode_device_is_available(con.fwnode))
                        continue;
@@ -32,6 +34,19 @@
                        return ret;
                }
        }
+
+       /* if the connector has no remote endpoint, check its parent */
+       if (!ep_count) {
+               con.fwnode = fwnode_get_parent(fwnode);
+               if (!con.fwnode)
+                       return NULL;
+
+               ret = match(&con, -1, data);
+               fwnode_handle_put(con.fwnode);
+               if (ret)
+                       return ret;
+       }
+
        return NULL;
 }

see attached patch.

then both usb_role_switch_get(dev) or fwnode_usb_role_switch_get(fwnode)
work well;

but I don't know which way is better when consider this specific case,
put into class.c as you suggested before or put into devcon.c like
above. 

Thanks a lot

> 
> thanks,
> 


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From bd291df4d0247fce5c11da746ae0761420054cf7 Mon Sep 17 00:00:00 2001
From: Chunfeng Yun <chunfeng.yun@mediatek.com>
Date: Thu, 23 May 2019 18:04:28 +0800
Subject: [PATCH] device connection: test only

Change-Id: Ie1b4b6304dfd7a89516fa3578aa5a5b1be924212
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
 drivers/base/devcon.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/base/devcon.c b/drivers/base/devcon.c
index 8311b70bbca2..1dae8b77562d 100644
--- a/drivers/base/devcon.c
+++ b/drivers/base/devcon.c
@@ -18,9 +18,11 @@ fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
 {
 	struct device_connection con = { .id = con_id };
 	struct fwnode_handle *ep;
+	int ep_count = 0;
 	void *ret;
 
 	fwnode_graph_for_each_endpoint(fwnode, ep) {
+		ep_count++;
 		con.fwnode = fwnode_graph_get_remote_port_parent(ep);
 		if (!fwnode_device_is_available(con.fwnode))
 			continue;
@@ -32,6 +34,19 @@ fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
 			return ret;
 		}
 	}
+
+	/* if the connector has no remote endpoint, check its parent */
+	if (!ep_count) {
+		con.fwnode = fwnode_get_parent(fwnode);
+		if (!con.fwnode)
+			return NULL;
+
+		ret = match(&con, -1, data);
+		fwnode_handle_put(con.fwnode);
+		if (ret)
+			return ret;
+	}
+
 	return NULL;
 }
 
-- 
2.21.0


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