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stm32/usbd_cdc_interface: Don't retransmit chars if USB is reconnected.

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Before this change, if the USB was reconnected it was possible that some
characters in the TX buffer were retransmitted because tx_buf_ptr_out and
tx_buf_ptr_out_shadow were reset while tx_buf_ptr_in wasn't.  That
behaviour is fixed here by retaining the TX buffer state across reconnects.

Fixes issue #4761.
This commit is contained in:
Damien George 2019-05-08 12:45:24 +10:00
parent 97753a1bbc
commit b8c74014e4
2 changed files with 6 additions and 6 deletions
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2
ports/stm32/usb.c
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@ -69,7 +69,7 @@ typedef struct _usb_device_t {
usbd_hid_itf_t usbd_hid_itf;
} usb_device_t;
usb_device_t usb_device;
usb_device_t usb_device = {0};
pyb_usb_storage_medium_t pyb_usb_storage_medium = PYB_USB_STORAGE_MEDIUM_NONE;
// predefined hid mouse data

10
ports/stm32/usbd_cdc_interface.c
View File

@ -64,14 +64,14 @@ static uint8_t usbd_cdc_connect_tx_timer;
uint8_t *usbd_cdc_init(usbd_cdc_state_t *cdc_in) {
usbd_cdc_itf_t *cdc = (usbd_cdc_itf_t*)cdc_in;
// Reset all the CDC state
// Note: we don't reset tx_buf_ptr_in in order to allow the output buffer to
// be filled (by usbd_cdc_tx_always) before the USB device is connected.
// Reset the CDC state due to a new USB host connection
// Note: we don't reset tx_buf_ptr_* in order to allow the output buffer to
// be filled (by usbd_cdc_tx_always) before the USB device is connected, and
// to retain transmit buffer state across multiple USB connections (they will
// be 0 at MCU reset since the variables live in the BSS).
cdc->rx_buf_put = 0;
cdc->rx_buf_get = 0;
cdc->rx_buf_full = false;
cdc->tx_buf_ptr_out = 0;
cdc->tx_buf_ptr_out_shadow = 0;
cdc->tx_need_empty_packet = 0;
cdc->connect_state = USBD_CDC_CONNECT_STATE_DISCONNECTED;