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Check usb_busy up front in usb background function. #679

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Merged
merged 1 commit into from
Mar 14, 2018
Merged

Check usb_busy up front in usb background function. #679

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11 changes: 9 additions & 2 deletions ports/atmel-samd/usb_mass_storage.c
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Original file line number Diff line number Diff line change
Expand Up @@ -280,15 +280,22 @@ int32_t usb_msc_xfer_done(uint8_t lun) {
// drive into our cache and trigger the USB DMA to output the
// sector. Once the sector is transmitted, xfer_done will be called.
void usb_msc_background(void) {
if (active_read && !usb_busy) {
// Check USB busy first because we never want to queue another transfer if it is. Checking
// active_read or active_write first leaves the possibility that they are true, an xfer done
// interrupt occurs (setting them false), turning off usb_busy and causing us to queue a
// spurious transfer.
if (usb_busy) {
return;
}
if (active_read) {
fs_user_mount_t * vfs = get_vfs(active_lun);
disk_read(vfs, sector_buffer, active_addr, 1);
CRITICAL_SECTION_ENTER();
int32_t result = mscdf_xfer_blocks(true, sector_buffer, 1);
usb_busy = result == ERR_NONE;
CRITICAL_SECTION_LEAVE();
}
if (active_write && !usb_busy) {
if (active_write) {
if (sector_loaded) {
fs_user_mount_t * vfs = get_vfs(active_lun);
disk_write(vfs, sector_buffer, active_addr, 1);
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