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usb: kbd: Add (optional) support for using an interrupt queue for polling

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Waiting an interrupt packet to complete in usb_kbd_poll_for_event, causes
a 40 ms latency for each call to usb_kbd_testc, which is undesirable.

Using control messages leads to lower (but still not 0) latency, but some
devices do not work well with control messages (e.g. my kvm behaves funny
with them).

This commit adds support for using the int_queue mechanism which at least
the ehci-hcd driver supports. This allows polling with 0 latency, while
using interrupt packets.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Hans de Goede 2014-09-24 14:06:11 +02:00 committed by Marek Vasut
parent 8f8d7d2451
commit 8e55311983
1 changed files with 19 additions and 0 deletions
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19
common/usb_kbd.c
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@ -102,6 +102,7 @@ struct usb_kbd_pdata {
unsigned long intpipe;
int intpktsize;
int intinterval;
struct int_queue *intq;
uint32_t repeat_delay;
@ -324,6 +325,15 @@ static inline void usb_kbd_poll_for_event(struct usb_device *dev)
1, 0, data->new, USB_KBD_BOOT_REPORT_SIZE);
if (memcmp(data->old, data->new, USB_KBD_BOOT_REPORT_SIZE))
usb_kbd_irq_worker(dev);
#elif defined(CONFIG_SYS_USB_EVENT_POLL_VIA_INT_QUEUE)
struct usb_kbd_pdata *data = dev->privptr;
if (poll_int_queue(dev, data->intq)) {
usb_kbd_irq_worker(dev);
/* We've consumed all queued int packets, create new */
destroy_int_queue(dev, data->intq);
data->intq = create_int_queue(dev, data->intpipe, 1,
USB_KBD_BOOT_REPORT_SIZE, data->new);
}
#endif
}
@ -441,8 +451,14 @@ static int usb_kbd_probe(struct usb_device *dev, unsigned int ifnum)
usb_set_idle(dev, iface->desc.bInterfaceNumber, REPEAT_RATE, 0);
debug("USB KBD: enable interrupt pipe...\n");
#ifdef CONFIG_SYS_USB_EVENT_POLL_VIA_INT_QUEUE
data->intq = create_int_queue(dev, data->intpipe, 1,
USB_KBD_BOOT_REPORT_SIZE, data->new);
if (!data->intq) {
#else
if (usb_submit_int_msg(dev, data->intpipe, data->new, data->intpktsize,
data->intinterval) < 0) {
#endif
printf("Failed to get keyboard state from device %04x:%04x\n",
dev->descriptor.idVendor, dev->descriptor.idProduct);
/* Abort, we don't want to use that non-functional keyboard. */
@ -526,6 +542,9 @@ int usb_kbd_deregister(int force)
data = usb_kbd_dev->privptr;
if (stdio_deregister_dev(dev, force) != 0)
return 1;
#ifdef CONFIG_SYS_USB_EVENT_POLL_VIA_INT_QUEUE
destroy_int_queue(usb_kbd_dev, data->intq);
#endif
free(data->new);
free(data);
}