Hi Heikki, > -----Original Message----- > From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > Sent: Monday, May 20, 2019 9:04 AM > To: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; > Matthias Brugger <matthias.bgg@xxxxxxxxx>; Adam Thomson > <Adam.Thomson.Opensource@xxxxxxxxxxx>; Li Jun <jun.li@xxxxxxx>; > Badhri Jagan Sridharan <badhri@xxxxxxxxxx>; Hans de Goede > <hdegoede@xxxxxxxxxx>; Andy Shevchenko > <andy.shevchenko@xxxxxxxxx>; Min Guo <min.guo@xxxxxxxxxxxx>; > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux- > usb@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > mediatek@xxxxxxxxxxxxxxxxxxx; Biju Das <biju.das@xxxxxxxxxxxxxx>; Linus > Walleij <linus.walleij@xxxxxxxxxx> > 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@xxxxxxxxxxxx> > > > > > Tested-by: Biju Das <biju.das@xxxxxxxxxxxxxx> > > > > > > > > Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > > > > > > 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/ regards, Biju > > > > > --- > > > > > v5 changes: > > > > > 1. remove linux/of.h suggested by Biju 2. add tested by Biju > > > > > > > > > > Note: still depends on [1] > > > > > [1]: [v6,08/13] usb: roles: Introduce stubs for the exiting functions in > role.h > > > > > https://patchwork.kernel.org/patch/10909971/ > > > > > > > > > > v4 changes: > > > > > 1. use switch_fwnode_match() to find fwnode suggested by Heikki > > > > > 2. this patch now depends on [1] > > > > > > > > > > [1] [v6,08/13] usb: roles: Introduce stubs for the exiting functions in > role.h > > > > > https://patchwork.kernel.org/patch/10909971/ > > > > > > > > > > v3 changes: > > > > > 1. use fwnodes instead of node suggested by Andy > > > > > 2. rebuild the API suggested by Heikki > > > > > > > > > > v2 no changes > > > > > --- > > > > > drivers/usb/roles/class.c | 24 ++++++++++++++++++++++++ > > > > > include/linux/usb/role.h | 8 ++++++++ > > > > > 2 files changed, 32 insertions(+) > > > > > > > > > > diff --git a/drivers/usb/roles/class.c > > > > > b/drivers/usb/roles/class.c index f45d8df5cfb8..4a1f09a41ec0 > > > > > 100644 > > > > > --- a/drivers/usb/roles/class.c > > > > > +++ b/drivers/usb/roles/class.c > > > > > @@ -135,6 +135,30 @@ struct usb_role_switch > > > > > *usb_role_switch_get(struct device *dev) } > > > > > EXPORT_SYMBOL_GPL(usb_role_switch_get); > > > > > > > > > > +/** > > > > > + * fwnode_usb_role_switch_get - Find USB role switch by it's > > > > > +parent fwnode > > > > > + * @fwnode: The fwnode that register USB role switch > > > > > + * > > > > > + * Finds and returns role switch registered by @fwnode. The > > > > > +reference count > > > > > + * for the found switch is incremented. > > > > > + */ > > > > > +struct usb_role_switch * > > > > > +fwnode_usb_role_switch_get(struct fwnode_handle *fwnode) { > > > > > + struct usb_role_switch *sw; > > > > > + struct device *dev; > > > > > + > > > > > + dev = class_find_device(role_class, NULL, fwnode, > switch_fwnode_match); > > > > > + if (!dev) > > > > > + return ERR_PTR(-EPROBE_DEFER); > > > > > + > > > > > + sw = to_role_switch(dev); > > > > > + WARN_ON(!try_module_get(sw->dev.parent->driver- > >owner)); > > > > > + > > > > > + return sw; > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(fwnode_usb_role_switch_get); > > > > > > This function only basically converts the fwnode to usb_role_switch, > > > but I would actually prefer that we walked through the device graph > > > here instead of expecting the caller to do that. > > > > > > So this function should probable be called > > > fwnode_to_usb_role_switch() and not fwnode_usb_role_switch_get(), > > > but I guess you don't need it at all, right? > > > > > > > > > thanks, > > > > > > > -- > heikki
