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Date: Wed, 24 Jun 2020 12:04:55 +0200
From: David Rheinsberg <david.rheinsberg@...il.com>
To: David Korth <gerbilsoft@...bilsoft.com>
Cc: Jiri Kosina <jikos@...nel.org>,
Benjamin Tissoires <benjamin.tissoires@...hat.com>,
"open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] HID: wiimote: Initialize the controller LEDs with a
device ID value
Hi
On Tue, Jun 23, 2020 at 12:57 AM David Korth <gerbilsoft@...bilsoft.com> wrote:
>
> Based on a similar commit for Sony Sixaxis and DualShock 4 controllers:
> HID: sony: Initialize the controller LEDs with a device ID value
>
> Wii remotes have the same player LED layout as Sixaxis controllers,
> so the wiimote setup is based on the Sixaxis code.
Please include a description of the patch in the commit-message. It
took me quite a while to understand what the intention of this patch
is.
> Signed-off-by: David Korth <gerbilsoft@...bilsoft.com>
> ---
> drivers/hid/hid-wiimote-core.c | 57 ++++++++++++++++++++++++++++++-
> drivers/hid/hid-wiimote-modules.c | 7 ----
> drivers/hid/hid-wiimote.h | 1 +
> 3 files changed, 57 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/hid/hid-wiimote-core.c b/drivers/hid/hid-wiimote-core.c
> index 92874dbe4d4a..9662c2ce5e99 100644
> --- a/drivers/hid/hid-wiimote-core.c
> +++ b/drivers/hid/hid-wiimote-core.c
> @@ -14,9 +14,12 @@
> #include <linux/module.h>
> #include <linux/mutex.h>
> #include <linux/spinlock.h>
> +#include <linux/idr.h>
> #include "hid-ids.h"
> #include "hid-wiimote.h"
>
> +static DEFINE_IDA(wiimote_device_id_allocator);
> +
> /* output queue handling */
>
> static int wiimote_hid_send(struct hid_device *hdev, __u8 *buffer,
> @@ -694,6 +697,10 @@ static void wiimote_modules_unload(struct wiimote_data *wdata)
> wdata->state.devtype = WIIMOTE_DEV_UNKNOWN;
> spin_unlock_irqrestore(&wdata->state.lock, flags);
>
> + if (wdata->device_id >= 0)
> + ida_simple_remove(&wiimote_device_id_allocator,
> + wdata->device_id);
> +
> /* find end of list */
> for (iter = mods; *iter != WIIMOD_NULL; ++iter)
> /* empty */ ;
> @@ -802,6 +809,20 @@ static const char *wiimote_devtype_names[WIIMOTE_DEV_NUM] = {
> [WIIMOTE_DEV_PRO_CONTROLLER] = "Nintendo Wii U Pro Controller",
> };
>
> +static __u8 wiimote_set_leds_from_id(int id)
> +{
> + static const __u8 wiimote_leds[10] = {
> + 0x01, 0x02, 0x04, 0x08,
> + 0x09, 0x0A, 0x0C, 0x0D,
> + 0x0E, 0x0F
> + };
> +
> + if (id < 0)
> + return wiimote_leds[0];
> +
> + return wiimote_leds[id % 10];
> +}
> +
> /* Try to guess the device type based on all collected information. We
> * first try to detect by static extension types, then VID/PID and the
> * device name. If we cannot detect the device, we use
> @@ -810,8 +831,10 @@ static void wiimote_init_set_type(struct wiimote_data *wdata,
> __u8 exttype)
> {
> __u8 devtype = WIIMOTE_DEV_GENERIC;
> + __u8 leds;
> __u16 vendor, product;
> const char *name;
> + int device_id;
>
> vendor = wdata->hdev->vendor;
> product = wdata->hdev->product;
> @@ -858,6 +881,24 @@ static void wiimote_init_set_type(struct wiimote_data *wdata,
> wiimote_devtype_names[devtype]);
>
> wiimote_modules_load(wdata, devtype);
> +
> + /* set player number to stop initial LED-blinking */
> + device_id = ida_simple_get(&wiimote_device_id_allocator, 0, 0,
> + GFP_KERNEL);
> + if (device_id < 0) {
> + /* Unable to get a device ID. */
> + /* Set LED1 anyway to stop the blinking. */
> + leds = WIIPROTO_FLAG_LED1;
> + wdata->device_id = -1;
> + } else {
> + /* Device ID obtained. */
> + leds = wiimote_set_leds_from_id(device_id);
> + wdata->device_id = device_id;
> + }
> +
> + spin_lock_irq(&wdata->state.lock);
> + wiiproto_req_leds(wdata, leds);
> + spin_unlock_irq(&wdata->state.lock);
So what you are trying is to allocate a unique ID to each connected
wiimote, so they automatically display unique IDs, right?
Can you explain why this has to be done in the kernel driver? Why
isn't user-space assigning the right ID? User-space needs to attach
controllers to their respective engine anyway, in which case the IDs
the kernel assigns would be wrong, right? How does user-space display
the matching ID in their UI (e.g., for configuration use-cases)? The
way you set them does not allow user-space to query the ID, does it?
Lastly, wouldn't a device-reconnect want the same ID to be assigned
again? With the logic you apply, user-space would have to override
every ID for that to work.
Is there an actual use-case for this? Or is this just to align the
driver with the other gamepads?
Thanks
David
> }
>
> static void wiimote_init_detect(struct wiimote_data *wdata)
> @@ -1750,6 +1791,8 @@ static struct wiimote_data *wiimote_create(struct hid_device *hdev)
> wdata->state.drm = WIIPROTO_REQ_DRM_K;
> wdata->state.cmd_battery = 0xff;
>
> + wdata->device_id = -1;
> +
> INIT_WORK(&wdata->init_worker, wiimote_init_worker);
> timer_setup(&wdata->timer, wiimote_init_timeout, 0);
>
> @@ -1879,7 +1922,19 @@ static struct hid_driver wiimote_hid_driver = {
> .remove = wiimote_hid_remove,
> .raw_event = wiimote_hid_event,
> };
> -module_hid_driver(wiimote_hid_driver);
> +
> +static int __init wiimote_init(void)
> +{
> + return hid_register_driver(&wiimote_hid_driver);
> +}
> +
> +static void __exit wiimote_exit(void)
> +{
> + ida_destroy(&wiimote_device_id_allocator);
> + hid_unregister_driver(&wiimote_hid_driver);
> +}
> +module_init(wiimote_init);
> +module_exit(wiimote_exit);
>
> MODULE_LICENSE("GPL");
> MODULE_AUTHOR("David Herrmann <dh.herrmann@...il.com>");
> diff --git a/drivers/hid/hid-wiimote-modules.c b/drivers/hid/hid-wiimote-modules.c
> index 2c3925357857..0cdd6c219b5d 100644
> --- a/drivers/hid/hid-wiimote-modules.c
> +++ b/drivers/hid/hid-wiimote-modules.c
> @@ -362,13 +362,6 @@ static int wiimod_led_probe(const struct wiimod_ops *ops,
> if (ret)
> goto err_free;
>
> - /* enable LED1 to stop initial LED-blinking */
> - if (ops->arg == 0) {
> - spin_lock_irqsave(&wdata->state.lock, flags);
> - wiiproto_req_leds(wdata, WIIPROTO_FLAG_LED1);
> - spin_unlock_irqrestore(&wdata->state.lock, flags);
> - }
> -
> return 0;
>
> err_free:
> diff --git a/drivers/hid/hid-wiimote.h b/drivers/hid/hid-wiimote.h
> index b2a26a0a8f12..800849427947 100644
> --- a/drivers/hid/hid-wiimote.h
> +++ b/drivers/hid/hid-wiimote.h
> @@ -160,6 +160,7 @@ struct wiimote_data {
> struct wiimote_queue queue;
> struct wiimote_state state;
> struct work_struct init_worker;
> + int device_id;
> };
>
> /* wiimote modules */
> --
> 2.27.0
>
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