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MIDI - Add flow control to incoming packet stream

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Larger SysEx transfers get corrupted by incoming packets.

This changes the FIFOs not to overwrite their data. MIDI should not be
a transport that drops packets. A potentially blocking device is easier
to detect and handle than a device that silently corrupts the packet
stream at random overflows, especially when SysEx messages are involved.
This commit is contained in:
Kay Sievers 2020-04-19 11:44:15 +02:00
parent f9262007ac
commit a0598ef369
1 changed files with 25 additions and 5 deletions
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30
src/class/midi/midi_device.c
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@ -85,6 +85,18 @@ bool tud_midi_n_mounted (uint8_t itf)
return midi->ep_in && midi->ep_out;
}
static void _prep_out_transaction (midid_interface_t* p_midi)
{
// skip if previous transfer not complete
if ( usbd_edpt_busy(TUD_OPT_RHPORT, p_midi->ep_out) )
return;
// Prepare for incoming data but only allow what we can store in the ring buffer.
uint16_t max_read = tu_fifo_remaining(&p_midi->rx_ff);
if ( max_read >= CFG_TUD_MIDI_EPSIZE )
usbd_edpt_xfer(TUD_OPT_RHPORT, p_midi->ep_out, p_midi->epout_buf, CFG_TUD_MIDI_EPSIZE);
}
//--------------------------------------------------------------------+
// READ API
//--------------------------------------------------------------------+
@ -138,11 +150,17 @@ void tud_midi_n_read_flush (uint8_t itf, uint8_t jack_id)
{
(void) jack_id;
tu_fifo_clear(&_midid_itf[itf].rx_ff);
if (tud_ready() && &_midid_itf[itf].ep_out != 0)
_prep_out_transaction(&_midid_itf[itf]);
}
bool tud_midi_n_receive (uint8_t itf, uint8_t packet[4])
{
return tu_fifo_read_n(&_midid_itf[itf].rx_ff, packet, 4);
if (tud_ready() && &_midid_itf[itf].ep_out != 0)
_prep_out_transaction(&_midid_itf[itf]);
return tu_fifo_read_n(&_midid_itf[itf].rx_ff, packet, 4) == 4;
}
void midi_rx_done_cb(midid_interface_t* midi, uint8_t const* buffer, uint32_t bufsize) {
@ -267,8 +285,8 @@ void midid_init(void)
midid_interface_t* midi = &_midid_itf[i];
// config fifo
tu_fifo_config(&midi->rx_ff, midi->rx_ff_buf, CFG_TUD_MIDI_RX_BUFSIZE, 1, true);
tu_fifo_config(&midi->tx_ff, midi->tx_ff_buf, CFG_TUD_MIDI_TX_BUFSIZE, 1, true);
tu_fifo_config(&midi->rx_ff, midi->rx_ff_buf, CFG_TUD_MIDI_RX_BUFSIZE, 1, false);
tu_fifo_config(&midi->tx_ff, midi->tx_ff_buf, CFG_TUD_MIDI_TX_BUFSIZE, 1, false);
#if CFG_FIFO_MUTEX
tu_fifo_config_mutex(&midi->rx_ff, osal_mutex_create(&midi->rx_ff_mutex));
@ -358,7 +376,7 @@ bool midid_open(uint8_t rhport, tusb_desc_interface_t const * desc_itf, uint16_t
*p_length = drv_len;
// Prepare for incoming data
TU_ASSERT( usbd_edpt_xfer(rhport, p_midi->ep_out, p_midi->epout_buf, CFG_TUD_MIDI_EPSIZE), false);
_prep_out_transaction(p_midi);
return true;
}
@ -381,6 +399,7 @@ bool midid_control_request(uint8_t rhport, tusb_control_request_t const * p_requ
bool midid_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
{
(void) rhport;
(void) result;
uint8_t itf = 0;
@ -399,7 +418,8 @@ bool midid_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32
midi_rx_done_cb(p_midi, p_midi->epout_buf, xferred_bytes);
// prepare for next
TU_ASSERT( usbd_edpt_xfer(rhport, p_midi->ep_out, p_midi->epout_buf, CFG_TUD_MIDI_EPSIZE), false );
_prep_out_transaction(p_midi);
} else if ( ep_addr == p_midi->ep_in ) {
maybe_transmit(p_midi, itf);
}