usb: kbd: Add (optional) support for using an interrupt queue for polling
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>
diff --git a/common/usb_kbd.c b/common/usb_kbd.c
index a303d95..bc7145e 100644
--- a/common/usb_kbd.c
+++ b/common/usb_kbd.c
@@ -102,6 +102,7 @@
unsigned long intpipe;
int intpktsize;
int intinterval;
+ struct int_queue *intq;
uint32_t repeat_delay;
@@ -324,6 +325,15 @@
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 @@
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 @@
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);
}