linux-kernel - Re: [PATCH 3/3] HID: usbhid: defer LED setting to a workqueue

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Message-ID: <CAGS+omAzL+RspmQ=GCAN+NSEyDddm=zXvJR99PPT8R=4OVGn4g@mail.gmail.com>
Date:	Wed, 14 Dec 2011 16:19:31 +0800
From:	Daniel Kurtz <djkurtz@...omium.org>
To:	Oliver Neukum <oneukum@...e.de>
Cc:	jkosina@...e.cz, bleung@...omium.org, stern@...land.harvard.edu,
	olofj@...omium.org, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH 3/3] HID: usbhid: defer LED setting to a workqueue

On Wed, Dec 14, 2011 at 4:01 PM, Oliver Neukum <oneukum@...e.de> wrote:
> Am Donnerstag, 17. November 2011, 12:23:50 schrieb Daniel Kurtz:
>> Defer LED setting action to a workqueue.
>> This is more likely to send all LED change events in a single URB.
>
> Hi,
>
> I hope I am looking at the correct version of this patch.

Yes, that is the correct version.  It looks like I forgot to bump r in
the [PATCH] of the subject.

> But as far as I can see the work for handling LEDs is not delayed
> while a reset is going on. That is wrong.

Good catch, I think.  Your comment is a bit terse, so it is difficult to
tell exactly what you are recommending.  Perhaps something like the following?

+/* Workqueue routine to send requests to change LEDs */
+static void hid_led(struct work_struct *work)
+{
+       struct usbhid_device *usbhid =
+               container_of(work, struct usbhid_device, led_work);
+       struct hid_device *hid = usbhid->hid;
+       struct hid_field *field;
+       unsigned long flags;
+
+       field = hidinput_get_led_field(hid);
+       if (!field) {
+               hid_warn(hid, "LED event field not found\n");
+               return;
+       }
+
+       spin_lock_irqsave(&usbhid->lock, flags);
+       if (!test_bit(HID_DISCONNECTED, &usbhid->iofl) &&
+           !test_bit(HID_RESET_PENDING, &usbhid->iofl)) {
+               usbhid->ledcount = hidinput_count_leds(hid);
+               hid_dbg(usbhid->hid, "New ledcount = %u\n", usbhid->ledcount);
+               __usbhid_submit_report(hid, field->report, USB_DIR_OUT);
+       }
+       spin_unlock_irqrestore(&usbhid->lock, flags);
+}


-Dan

>
>        Regards
>                Oliver
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