Messages in this thread | | | Date | Thu, 25 Jul 2019 15:44:11 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 01/12 v2] Platform: add a dev_groups pointer to struct platform_driver |
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On Sat, Jul 20, 2019 at 07:38:57AM +0300, Dmitry Torokhov wrote: > On Fri, Jul 19, 2019 at 08:52:20PM +0900, Greg Kroah-Hartman wrote: > > On Sat, Jul 06, 2019 at 10:39:38AM -0700, Dmitry Torokhov wrote: > > > On Sat, Jul 6, 2019 at 10:19 AM Greg Kroah-Hartman > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > On Sat, Jul 06, 2019 at 10:04:39AM -0700, Dmitry Torokhov wrote: > > > > > Hi Greg, > > > > > > > > > > On Sat, Jul 6, 2019 at 1:32 AM Greg Kroah-Hartman > > > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > > > > > On Thu, Jul 04, 2019 at 02:17:22PM -0700, Dmitry Torokhov wrote: > > > > > > > Hi Greg, > > > > > > > > > > > > > > On Thu, Jul 4, 2019 at 5:15 AM Greg Kroah-Hartman > > > > > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > > > > > > > > > Platform drivers like to add sysfs groups to their device, but right now > > > > > > > > they have to do it "by hand". The driver core should handle this for > > > > > > > > them, but there is no way to get to the bus-default attribute groups as > > > > > > > > all platform devices are "special and unique" one-off drivers/devices. > > > > > > > > > > > > > > > > To combat this, add a dev_groups pointer to platform_driver which allows > > > > > > > > a platform driver to set up a list of default attributes that will be > > > > > > > > properly created and removed by the platform driver core when a probe() > > > > > > > > function is successful and removed right before the device is unbound. > > > > > > > > > > > > > > Why is this limited to platform bus? Drivers for other buses also > > > > > > > often want to augment list of their attributes during probe(). I'd > > > > > > > move it to generic probe handling. > > > > > > > > > > > > This is not limited to the platform at all, the driver core supports > > > > > > this for any bus type today, but it's then up to the bus-specific code > > > > > > to pass that on to the driver core. That's usually set for the > > > > > > bus-specific attributes that they want exposed for all devices of that > > > > > > bus type (see the bus_groups, dev_groups, and drv_groups pointers in > > > > > > struct bus_type). > > > > > > > > > > > > For the platform devices, the problem is that this is something that the > > > > > > individual drivers want after they bind to the device. And as all > > > > > > platform devices are "different" they can't be a "common" set of > > > > > > attributes, so they need to be created after the device is bound to the > > > > > > driver. > > > > > > > > > > I believe that your assertion that only platform devices want to > > > > > install custom attributes is incorrect. > > > > > > > > Sorry, I didn't mean to imply that only platform drivers want to do > > > > this, as you say, many other drivers do as well. > > > > > > > > > Drivers for devices attached > > > > > to serio, i2c, USB, spi, etc, etc, all have additional attributes: > > > > > > > > > > dtor@dtor-ws:~/kernel/work (master *)$ grep -l '\(i2c\|usb\|spi\)' > > > > > `git grep -l '\(device_add_group\|sysfs_create_group\)' -- drivers` | > > > > > wc -l > > > > > 170 > > > > > > > > > > I am pretty sure some of this count is false positives, but majority > > > > > is actually proper hits. > > > > > > > > Yeah, I know, we need to add this type of functionality to those busses > > > > as well. I don't see a way of doing it other than this bus-by-bus > > > > conversion, do you? > > > > > > Can't you push the **dev_groups from platform driver down to the > > > generic driver structure and handle them in driver_sysfs_add()? > > > > Sorry for the delay, got busy with the merge window... > > > > Anyway, no, we can't call this then, because driver_sysfs_add() is > > called before probe() is called. So if probe() fails, we don't bind the > > device to the driver. We also should not be creating sysfs files for a > > driver that has not had probe() called yet, as internal structures will > > not be set up at that time. > > Ah, yes, I got confused by the fact that driver_sysfs_remove is called > early. Anyway, I think you want something like this:
Ah, nice, this looks good. Let me try this and see how it goes...
> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 0df9b4461766..61d9d650d890 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -515,9 +515,17 @@ static int really_probe(struct device *dev, struct device_driver *drv) > goto probe_failed; > } > > + if (device_add_groups(dev, drv->dev_groups)) { > + printk(KERN_ERR "%s: device_add_groups(%s) failed\n", > + __func__, dev_name(dev));
dev_err() of course :)
thanks for the review, much appreciated.
greg k-h
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