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stm32: Fix usbfs spurious USB packet transmit on startup 

Commit cd8d57c2 added USB double buffering mode on transmits.
However, when enabling double buffering mode, the hardware seems to
always send at least two packets.  Spurious transmissions could cause
the Linux gs_usb driver to get confused, which could lead to the can0
device becoming unavailable on restarts.  Fix by waiting for two USB
packets to be available before enabling the endpoint.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2023-10-04 19:34:22 -04:00
parent 615db729e7
commit 043f18da26
1 changed files with 16 additions and 6 deletions
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20
src/stm32/usbfs.c
View File

@ -236,7 +236,8 @@ usb_read_bulk_out(void *data, uint_fast8_t max_len)
return count;
}
static uint32_t bulk_in_push_count, bulk_in_pop_flag;
static uint32_t bulk_in_push_pos, bulk_in_pop_flag;
#define BI_START 2
int_fast8_t
usb_send_bulk_in(void *data, uint_fast8_t len)
@ -245,8 +246,8 @@ usb_send_bulk_in(void *data, uint_fast8_t len)
// No buffer space available
return -1;
uint32_t ep = USB_CDC_EP_BULK_IN;
int bufnum = bulk_in_push_count & 1;
bulk_in_push_count++;
uint32_t bipp = bulk_in_push_pos, bufnum = bipp & 1;
bulk_in_push_pos = bipp ^ 1;
btable_write_packet(ep, bufnum, data, len);
writel(&bulk_in_pop_flag, USB_EP_DTOG_RX);
@ -254,8 +255,18 @@ usb_send_bulk_in(void *data, uint_fast8_t len)
uint32_t epr = USB_EPR[ep];
if (epr_is_dbuf_blocking(epr) && readl(&bulk_in_pop_flag)) {
writel(&bulk_in_pop_flag, 0);
if (bipp & BI_START) {
// Two packets are always sent when starting in double
// buffering mode, so wait for second packet before starting.
if (bipp == (BI_START | 1)) {
bulk_in_push_pos = 0;
USB_EPR[ep] = calc_epr_bits(epr, USB_EPTX_STAT
, USB_EP_TX_VALID);
}
} else {
USB_EPR[ep] = calc_epr_bits(epr, 0, 0) | USB_EP_DTOG_RX;
}
}
return len;
}
@ -319,9 +330,8 @@ usb_set_configure(void)
USB_EPR[ep] = calc_epr_bits(USB_EPR[ep], USB_EPRX_STAT, USB_EP_RX_VALID);
ep = USB_CDC_EP_BULK_IN;
bulk_in_push_count = 0;
bulk_in_push_pos = BI_START;
writel(&bulk_in_pop_flag, 0);
USB_EPR[ep] = calc_epr_bits(USB_EPR[ep], USB_EPTX_STAT, USB_EP_TX_VALID);
}