Messages in this thread | | | Date | Sat, 22 Feb 2020 09:38:44 +0100 | From | Boris Brezillon <> | Subject | Re: [PATCH v3 3/5] i3c: master: add i3c_for_each_dev helper |
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On Fri, 21 Feb 2020 17:44:28 +0100 Boris Brezillon <boris.brezillon@collabora.com> wrote:
> On Fri, 21 Feb 2020 13:59:11 +0100 > Boris Brezillon <boris.brezillon@collabora.com> wrote: > > > On Fri, 21 Feb 2020 12:52:29 +0100 > > Greg KH <gregkh@linuxfoundation.org> wrote: > > > > > On Fri, Feb 21, 2020 at 11:47:22AM +0000, Vitor Soares wrote: > > > > Hi Greg, > > > > > > > > From: Greg KH <gregkh@linuxfoundation.org> > > > > Date: Wed, Feb 19, 2020 at 07:35:48 > > > > > > > > > On Wed, Feb 19, 2020 at 01:20:41AM +0100, Vitor Soares wrote: > > > > > > Introduce i3c_for_each_dev(), an i3c device iterator for use by i3cdev. > > > > > > > > > > > > Signed-off-by: Vitor Soares <vitor.soares@synopsys.com> > > > > > > --- > > > > > > drivers/i3c/internals.h | 1 + > > > > > > drivers/i3c/master.c | 12 ++++++++++++ > > > > > > 2 files changed, 13 insertions(+) > > > > > > > > > > > > diff --git a/drivers/i3c/internals.h b/drivers/i3c/internals.h > > > > > > index bc062e8..a6deedf 100644 > > > > > > --- a/drivers/i3c/internals.h > > > > > > +++ b/drivers/i3c/internals.h > > > > > > @@ -24,4 +24,5 @@ int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev); > > > > > > int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev, > > > > > > const struct i3c_ibi_setup *req); > > > > > > void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev); > > > > > > +int i3c_for_each_dev(void *data, int (*fn)(struct device *, void *)); > > > > > > #endif /* I3C_INTERNAL_H */ > > > > > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c > > > > > > index 21c4372..8e22da2 100644 > > > > > > --- a/drivers/i3c/master.c > > > > > > +++ b/drivers/i3c/master.c > > > > > > @@ -2640,6 +2640,18 @@ void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev) > > > > > > dev->ibi = NULL; > > > > > > } > > > > > > > > > > > > +int i3c_for_each_dev(void *data, int (*fn)(struct device *, void *)) > > > > > > +{ > > > > > > + int res; > > > > > > + > > > > > > + mutex_lock(&i3c_core_lock); > > > > > > + res = bus_for_each_dev(&i3c_bus_type, NULL, data, fn); > > > > > > + mutex_unlock(&i3c_core_lock); > > > > > > > > > > Ick, why the lock? Are you _sure_ you need that? The core should > > > > > handle any list locking issues here, right? > > > > > > > > I want to make sure that no new devices (eg: Hot-Join capable device) are > > > > added during this iteration and after this call, each new device will > > > > release a bus notification. > > > > > > > > > > > > > > I don't see bus-specific-locks around other subsystem functions that do > > > > > this (like usb_for_each_dev). > > > > > > > > I based in I2C use case. > > > > > > Check to see if this is really needed, for some reason I doubt it... > > > > Can we please try the spidev approach before fixing those problems. None > > of that would be needed if we declare the i3cdev driver as a regular > > i3c_device_driver and let user space bind devices it wants to expose > > through the sysfs interface. As I said earlier, we even have all the > > pieces we need to automate that using a udev rule, and the resulting > > patchset would be 'less invasive'/simpler for pretty much the same > > result. > > So, I went ahead and implemented it the way I suggest. The diffstat is > not representative here (though it's still in favor of this new version) > since I also changed the way we expose/handle SDR transfers. What's > most important IMO is the fact that > > * we no longer need to access the internal I3C API > * we no longer need to care about transitions between i3cdev and > other drivers (the core guarantees that a device is always bound to at > most one driver) > * the registration/unregistration procedure is simplified
Looks like I was wrong, there's no way to disable auto-binding and keep manual binding possible (they both use the bus->match() hook to know if a dev can be attached to a driver, and the type of binding is not specified here). There are of course other options to do this:
* add a i3c_driver->match() hook and expose driver-specific sysfs knobs to explicitly add devices to attach to this driver * make the i3cdev module register one driver per-device, each time with its own i3c_device_id table and add sysfs knobs to trigger this registration
but none of these option sounds reasonable to me, so let's pursue with your approach.
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