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atmel-samd: Improve MSC reliability.

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* Be more liberal with critical sections to ensure ordering.
* Correct usb_busy so that it is busy when no errors occur on
  transfer. I believe it worked before because it would be false
  momentarily until a second transfer was attempted and a busy
  error was returned, therefore setting usb_busy to true. That
  risks the first "failed" transfer completing before a second one
  is attempted.
This commit is contained in:
Scott Shawcroft 2017-11-08 12:42:50 -08:00
parent 7a901cfccd
commit 971bd7e9a6
1 changed files with 13 additions and 4 deletions
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17
ports/atmel-samd/usb_mass_storage.c
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@ -256,6 +256,7 @@ int32_t usb_msc_xfer_done(uint8_t lun) {
return ERR_DENIED;
}
CRITICAL_SECTION_ENTER();
if (active_read) {
active_addr += 1;
active_nblocks--;
@ -268,6 +269,7 @@ int32_t usb_msc_xfer_done(uint8_t lun) {
sector_loaded = true;
}
usb_busy = false;
CRITICAL_SECTION_LEAVE();
return ERR_NONE;
}
@ -277,9 +279,10 @@ void usb_msc_background(void) {
if (active_read && !usb_busy) {
fs_user_mount_t * vfs = get_vfs(active_lun);
disk_read(vfs, sector_buffer, active_addr, 1);
// TODO(tannewt): Check the read result.
mscdf_xfer_blocks(true, sector_buffer, 1);
usb_busy = true;
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 (sector_loaded) {
@ -306,8 +309,14 @@ void usb_msc_background(void) {
}
// Load more blocks from USB if they are needed.
if (active_nblocks > 0) {
// Turn off interrupts because with them on,
// usb_msc_xfer_done could be called before we update
// usb_busy. If that happened, we'd overwrite the fact that
// the transfer actually already finished.
CRITICAL_SECTION_ENTER();
int32_t result = mscdf_xfer_blocks(false, sector_buffer, 1);
usb_busy = result != ERR_NONE;
usb_busy = result == ERR_NONE;
CRITICAL_SECTION_LEAVE();
} else {
mscdf_xfer_blocks(false, NULL, 0);
active_write = false;