From 8ef6249e01f44e9a789e04b1d5baf1e77bfff6ae Mon Sep 17 00:00:00 2001
From: Epagris <wabe@t-email.hu>
Date: Fri, 19 Apr 2024 14:01:17 +0200
Subject: [PATCH] - driver: only poll FIFO free space if transmission size > 0
 - CDC: buffer size increased

---
 class/cdc.c  |  4 +++-
 usb_driver.c | 15 +++++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/class/cdc.c b/class/cdc.c
index a7fd1e3..e256520 100644
--- a/class/cdc.c
+++ b/class/cdc.c
@@ -12,11 +12,13 @@
 static USB_CdcState cdcs = { 0 };
 static uint8_t tx_buffer[USB_CDC_PCKT_BUFSIZE];
 
-#define USB_CDC_FIFO_MEM_SIZE (2048)
+#define USB_CDC_FIFO_MEM_SIZE (3072) // FIXME: ez vagy a blocking FIFO bugos
 
 static uint8_t fifo_mem[USB_CDC_FIFO_MEM_SIZE];
 static BFifo fifo;
 
+void usb_cdc_read_callback(const uint8_t * data, uint32_t size);
+
 void usb_cdc_init(const USB_CdcAssignments *as) {
     // clear the structure
     memset(&cdcs, 0, sizeof(USB_CdcState));
diff --git a/usb_driver.c b/usb_driver.c
index ff3f808..4317650 100644
--- a/usb_driver.c
+++ b/usb_driver.c
@@ -267,7 +267,7 @@ void usbdrv_build_fifo() {
         if (cfg->is_configured) {
             cfg->fifo_size = CEIL4(MAX(USB_MIN_GROSS_TX_FIFO_SIZE, cfg->max_packet_size)); // correct FIFO size if necessary
             cfg->fifo_address = next_fifo_addr;                                            // store FIFO address
-            cfg->zlp_next = false;                                                         // clear ZLP next 
+            cfg->zlp_next = false;                                                         // clear ZLP next
             next_fifo_addr += cfg->fifo_size;                                              // advance next address
         }
     }
@@ -476,8 +476,11 @@ uint32_t usbdrv_arm_IN_endpoint(uint8_t ep, const uint8_t *data, uint16_t len) {
     }
 
     // determine final write size
-    uint32_t freeSize = USBINEP[ep].DTXFSTS * sizeof(uint32_t); // get free transmit buffer size
-    uint16_t writeSize = MIN(freeSize, len);                    // limit transmit size to free size
+    uint32_t freeSize = 0;
+    if (len > 0) { // only poll DTXFSTS if (len > 0) (see datasheet)
+        freeSize = USBINEP[ep].DTXFSTS * sizeof(uint32_t); // get free transmit buffer size
+    }
+    uint16_t writeSize = MIN(freeSize, len); // limit transmit size to free size
 
     // calculate packet count based on max packet size
     uint16_t mps = gs.ep_IN[ep].max_packet_size;
@@ -486,10 +489,10 @@ uint32_t usbdrv_arm_IN_endpoint(uint8_t ep, const uint8_t *data, uint16_t len) {
         packet_count = writeSize / mps + (((writeSize % mps) > 0) ? 1 : 0);
     }
 
-    // set zlp_next if transmission size is integer multiple of max packet size
+    // set zlp_next if transmission size is integer multiple of max packet size6
     gs.ep_IN[ep].zlp_next = (writeSize > 0) && ((writeSize % mps) == 0);
 
-    // program DIEPTSIZ with transfer length (TODO: currently only a single transfer!)
+    // program DIEPTSIZ with transfer length
     USBINEP[ep].DIEPTSIZ = (packet_count << USB_OTG_DIEPTSIZ_PKTCNT_Pos) | writeSize;
 
     // enable endpoint and cancel responding NAK
@@ -690,7 +693,7 @@ void usbdrv_process_event(uint8_t evt_code, USBDRV_EventData *evt_data) {
                         // see if a ZLP transmission was queued
                         if (gs.ep_IN[ep].zlp_next) {
                             usbdrv_arm_IN_endpoint(ep, NULL, 0); // send ZLP
-                        } else { // no ZLP
+                        } else {                                 // no ZLP
                             USBMSG("IN [%d]\n", ep);
 
                             cbcpd.code = USB_CBC_IN_DONE;