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chip/stm32/usb_hid_keyboard: Simpler buffer handling

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As suggested in CL:411741, makes the follow-up CL that buffers
key strokes much simpler.

We can revisit later if we can still sneak it that change, but,
all in all, we can guarantee the same key latency by halving the
USB endpoint interval.

BRANCH=none
BUG=b:35775048
TEST=Connect hammer, keyboard works.

Change-Id: I6624fde9bd5561ddceb7ce195470d7af7cca7140
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/471187
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
This commit is contained in:
Nicolas Boichat
2017-08-10 14:36:06 +08:00
committed by chrome-bot
parent 9e33d6ce3c
commit 5adaee4156
1 changed files with 17 additions and 31 deletions
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48
chip/stm32/usb_hid_keyboard.c
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@@ -54,7 +54,7 @@ struct usb_hid_keyboard_report {
#define HID_KEYBOARD_REPORT_SIZE sizeof(struct usb_hid_keyboard_report)
#define HID_KEYBOARD_EP_INTERVAL_MS 32 /* ms */
#define HID_KEYBOARD_EP_INTERVAL_MS 16 /* ms */
/* Modifiers keycode range */
#define HID_KEYBOARD_MODIFIER_LOW 0xe0
@@ -172,41 +172,28 @@ const struct usb_hid_descriptor USB_CUSTOM_DESC_VAR(USB_IFACE_HID_KEYBOARD,
#define EP_BUF_SIZE DIV_ROUND_UP(HID_KEYBOARD_REPORT_SIZE, 2)
static usb_uint hid_ep_buf[2][EP_BUF_SIZE] __usb_ram;
static volatile int hid_current_buf;
static usb_uint hid_ep_buf[EP_BUF_SIZE] __usb_ram;
static volatile int hid_ep_data_ready;
static struct usb_hid_keyboard_report report;
static void write_keyboard_report(void)
{
/* Prevent the interrupt handler from sending the data (which would use
* an incomplete buffer).
*/
hid_ep_data_ready = 0;
hid_current_buf = hid_current_buf ? 0 : 1;
memcpy_to_usbram((void *) usb_sram_addr(hid_ep_buf[hid_current_buf]),
&report, sizeof(report));
/* Tell the interrupt handler to send the next buffer. */
hid_ep_data_ready = 1;
if ((STM32_USB_EP(USB_EP_HID_KEYBOARD) & EP_TX_MASK) == EP_TX_VALID) {
/* Endpoint is busy: we sneak in an address change to give us a
* chance to send the most updated report. However, there is no
* guarantee that this buffer is the one actually sent, so we
* keep hid_ep_data_ready = 1, which will send a duplicated
* report.
/* Endpoint is busy */
return;
}
if (atomic_read_clear(&hid_ep_data_ready)) {
/*
* Endpoint is not busy, and interrupt handler did not just
* send the buffer: enable TX.
*/
btable_ep[USB_EP_HID_KEYBOARD].tx_addr =
usb_sram_addr(hid_ep_buf[hid_current_buf]);
hid_ep_data_ready = 1;
} else if (atomic_read_clear(&hid_ep_data_ready)) {
/* Endpoint is not busy, and interrupt handler did not just
* send our last buffer: swap buffer, enable TX.
*/
btable_ep[USB_EP_HID_KEYBOARD].tx_addr =
usb_sram_addr(hid_ep_buf[hid_current_buf]);
memcpy_to_usbram((void *) usb_sram_addr(hid_ep_buf),
&report, sizeof(report));
STM32_TOGGLE_EP(USB_EP_HID_KEYBOARD, EP_TX_MASK,
EP_TX_VALID, 0);
}
@@ -219,19 +206,18 @@ static void hid_keyboard_tx(void)
{
hid_tx(USB_EP_HID_KEYBOARD);
if (hid_ep_data_ready) {
/* swap buffer, enable TX */
btable_ep[USB_EP_HID_KEYBOARD].tx_addr =
usb_sram_addr(hid_ep_buf[hid_current_buf]);
memcpy_to_usbram((void *) usb_sram_addr(hid_ep_buf),
&report, sizeof(report));
STM32_TOGGLE_EP(USB_EP_HID_KEYBOARD, EP_TX_MASK,
EP_TX_VALID, 0);
hid_ep_data_ready = 0;
}
hid_ep_data_ready = 0;
}
static void hid_keyboard_event(enum usb_ep_event evt)
{
if (evt == USB_EVENT_RESET)
hid_reset(USB_EP_HID_KEYBOARD, hid_ep_buf[hid_current_buf],
hid_reset(USB_EP_HID_KEYBOARD, hid_ep_buf,
HID_KEYBOARD_REPORT_SIZE);
}