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Date: Tue, 6 Mar 2018 15:21:00 +0100
From: Benjamin Tissoires <benjamin.tissoires@...hat.com>
To: Jiri Kosina <jikos@...nel.org>
Cc: "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>,
Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: Re: [PATCH 1/1] HID: core: rewrite the hid-generic automatic unbind
Hi Jiri,
On Fri, Dec 8, 2017 at 3:29 PM, Benjamin Tissoires
<benjamin.tissoires@...hat.com> wrote:
> We actually can have the unbind/rebind logic in hid-core.c, leaving
> only the match function in hid-generic.
> This makes hid-generic simpler and the whole logic simpler too.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
>
> Hi Jiri,
>
> while trying to find out a local bug, I figured out we don't really
> need the bus_add_driver and bus_removed_driver callbacks.
>
> This makes the code simpler and also allows other drivers to remove
> themself if other conditions are met. They just need to implement a smart
> enough .matchcallback and they are done.
>
Looks like you are reviewing HID patches right now :)
I just wanted to dig this one out from your mailbox. I still think
it's valuable.
IIRC it should still apply on your tree, but if not, I can quickly
update the patch.
Cheers,
Benjamin
> drivers/hid/hid-core.c | 35 ++++++++++++++++++++++++-----------
> drivers/hid/hid-generic.c | 33 ---------------------------------
> include/linux/hid.h | 4 ----
> 3 files changed, 24 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index c2560aae5542..c058bb911ca1 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2197,31 +2197,40 @@ void hid_destroy_device(struct hid_device *hdev)
> EXPORT_SYMBOL_GPL(hid_destroy_device);
>
>
> -static int __bus_add_driver(struct device_driver *drv, void *data)
> +static int __hid_bus_reprobe_drivers(struct device *dev, void *data)
> {
> - struct hid_driver *added_hdrv = data;
> - struct hid_driver *hdrv = to_hid_driver(drv);
> + struct hid_driver *hdrv = data;
> + struct hid_device *hdev = to_hid_device(dev);
>
> - if (hdrv->bus_add_driver)
> - hdrv->bus_add_driver(added_hdrv);
> + if (hdev->driver == hdrv &&
> + !hdrv->match(hdev, hid_ignore_special_drivers))
> + return device_reprobe(dev);
>
> return 0;
> }
>
> -static int __bus_removed_driver(struct device_driver *drv, void *data)
> +static int __hid_bus_driver_added(struct device_driver *drv, void *data)
> {
> - struct hid_driver *removed_hdrv = data;
> struct hid_driver *hdrv = to_hid_driver(drv);
>
> - if (hdrv->bus_removed_driver)
> - hdrv->bus_removed_driver(removed_hdrv);
> + if (hdrv->match) {
> + bus_for_each_dev(&hid_bus_type, NULL, hdrv,
> + __hid_bus_reprobe_drivers);
> + }
>
> return 0;
> }
>
> +static int __bus_removed_driver(struct device_driver *drv, void *data)
> +{
> + return bus_rescan_devices(&hid_bus_type);
> +}
> +
> int __hid_register_driver(struct hid_driver *hdrv, struct module *owner,
> const char *mod_name)
> {
> + int ret;
> +
> hdrv->driver.name = hdrv->name;
> hdrv->driver.bus = &hid_bus_type;
> hdrv->driver.owner = owner;
> @@ -2230,9 +2239,13 @@ int __hid_register_driver(struct hid_driver *hdrv, struct module *owner,
> INIT_LIST_HEAD(&hdrv->dyn_list);
> spin_lock_init(&hdrv->dyn_lock);
>
> - bus_for_each_drv(&hid_bus_type, NULL, hdrv, __bus_add_driver);
> + ret = driver_register(&hdrv->driver);
> +
> + if (ret == 0)
> + bus_for_each_drv(&hid_bus_type, NULL, NULL,
> + __hid_bus_driver_added);
>
> - return driver_register(&hdrv->driver);
> + return ret;
> }
> EXPORT_SYMBOL_GPL(__hid_register_driver);
>
> diff --git a/drivers/hid/hid-generic.c b/drivers/hid/hid-generic.c
> index 3c0a1bf433d7..c25b4718de44 100644
> --- a/drivers/hid/hid-generic.c
> +++ b/drivers/hid/hid-generic.c
> @@ -26,37 +26,6 @@
>
> static struct hid_driver hid_generic;
>
> -static int __unmap_hid_generic(struct device *dev, void *data)
> -{
> - struct hid_driver *hdrv = data;
> - struct hid_device *hdev = to_hid_device(dev);
> -
> - /* only unbind matching devices already bound to hid-generic */
> - if (hdev->driver != &hid_generic ||
> - hid_match_device(hdev, hdrv) == NULL)
> - return 0;
> -
> - if (dev->parent) /* Needed for USB */
> - device_lock(dev->parent);
> - device_release_driver(dev);
> - if (dev->parent)
> - device_unlock(dev->parent);
> -
> - return 0;
> -}
> -
> -static void hid_generic_add_driver(struct hid_driver *hdrv)
> -{
> - bus_for_each_dev(&hid_bus_type, NULL, hdrv, __unmap_hid_generic);
> -}
> -
> -static void hid_generic_removed_driver(struct hid_driver *hdrv)
> -{
> - int ret;
> -
> - ret = driver_attach(&hid_generic.driver);
> -}
> -
> static int __check_hid_generic(struct device_driver *drv, void *data)
> {
> struct hid_driver *hdrv = to_hid_driver(drv);
> @@ -97,8 +66,6 @@ static struct hid_driver hid_generic = {
> .name = "hid-generic",
> .id_table = hid_table,
> .match = hid_generic_match,
> - .bus_add_driver = hid_generic_add_driver,
> - .bus_removed_driver = hid_generic_removed_driver,
> };
> module_hid_driver(hid_generic);
>
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index 091a81cf330f..a62ee4a609ac 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -686,8 +686,6 @@ struct hid_usage_id {
> * @input_mapped: invoked on input registering after mapping an usage
> * @input_configured: invoked just before the device is registered
> * @feature_mapping: invoked on feature registering
> - * @bus_add_driver: invoked when a HID driver is about to be added
> - * @bus_removed_driver: invoked when a HID driver has been removed
> * @suspend: invoked on suspend (NULL means nop)
> * @resume: invoked on resume if device was not reset (NULL means nop)
> * @reset_resume: invoked on resume if device was reset (NULL means nop)
> @@ -742,8 +740,6 @@ struct hid_driver {
> void (*feature_mapping)(struct hid_device *hdev,
> struct hid_field *field,
> struct hid_usage *usage);
> - void (*bus_add_driver)(struct hid_driver *driver);
> - void (*bus_removed_driver)(struct hid_driver *driver);
> #ifdef CONFIG_PM
> int (*suspend)(struct hid_device *hdev, pm_message_t message);
> int (*resume)(struct hid_device *hdev);
> --
> 2.14.3
>
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