Merge pull request #12402 from ant9000/pr/usbus_cdc_acm_stdio_fix

Fix to avoid lost characters on USBUS CDC ACM STDIO

sys/usb/usbus/cdc/acm/cdc_acm.c

@@ -145,15 +145,35 @@ static size_t _gen_full_acm_descriptor(usbus_t *usbus, void *arg)
 /* Submit (ACM interface in) */
 size_t usbus_cdc_acm_submit(usbus_cdcacm_device_t *cdcacm, const uint8_t *buf, size_t len)
 {
-    return tsrb_add(&cdcacm->tsrb, buf, len);
+    size_t n;
+    unsigned old;
+    if (cdcacm->state != USBUS_CDC_ACM_LINE_STATE_DISCONNECTED) {
+        old = irq_disable();
+        n = tsrb_add(&cdcacm->tsrb, buf, len);
+        irq_restore(old);
+        return n;
+    }
+    /* stuff as much data as possible into tsrb, discarding the oldest */
+    old = irq_disable();
+    n = tsrb_free(&cdcacm->tsrb);
+    if (len > n) {
+        n += tsrb_drop(&cdcacm->tsrb, len - n);
+        buf += len - n;
+    } else {
+        n = len;
+    }
+    tsrb_add(&cdcacm->tsrb, buf, n);
+    /* behave as if everything has been written correctly */
+    irq_restore(old);
+    return len;
 }
 
 void usbus_cdc_acm_set_coding_cb(usbus_cdcacm_device_t *cdcacm,
                                  usbus_cdcacm_coding_cb_t coding_cb)
 {
-    irq_disable();
+    unsigned old = irq_disable();
     cdcacm->coding_cb = coding_cb;
-    irq_enable();
+    irq_restore(old);
 }
 
 /* flush event */
@@ -297,6 +317,8 @@ static void _handle_in(usbus_cdcacm_device_t *cdcacm,
         (cdcacm->state != USBUS_CDC_ACM_LINE_STATE_DTE)) {
         return;
     }
+    /* copy at most USBUS_CDC_ACM_BULK_EP_SIZE chars from input into ep->buf */
+    unsigned old = irq_disable();
     while (!tsrb_empty(&cdcacm->tsrb)) {
         int c = tsrb_get_one(&cdcacm->tsrb);
         ep->buf[cdcacm->occupied++] = (uint8_t)c;
@@ -304,6 +326,7 @@ static void _handle_in(usbus_cdcacm_device_t *cdcacm,
             break;
         }
     }
+    irq_restore(old);
     usbdev_ep_ready(ep, cdcacm->occupied);
 }
 

sys/usb/usbus/cdc/acm/cdc_acm_stdio.c

@@ -52,10 +52,15 @@ ssize_t stdio_read(void* buffer, size_t len)
 
 ssize_t stdio_write(const void* buffer, size_t len)
 {
-    usbus_cdc_acm_submit(&cdcacm, buffer, len);
-    usbus_cdc_acm_flush(&cdcacm);
-    /* Use tsrb and flush */
-    return len;
+    const char *start = buffer;
+    do {
+        size_t n = usbus_cdc_acm_submit(&cdcacm, buffer, len);
+        usbus_cdc_acm_flush(&cdcacm);
+        /* Use tsrb and flush */
+        buffer = (char *)buffer + n;
+        len -= n;
+    } while (len);
+    return start - (char *)buffer;
 }
 
 static void _cdc_acm_rx_pipe(usbus_cdcacm_device_t *cdcacm,

tests/usbus_cdc_acm_stdio/main.c

@@ -18,16 +18,46 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "shell.h"
 #include "shell_commands.h"
 
+static int cmd_text(int argc, char **argv)
+{
+    char *usage = "text [length]\n";
+    if (argc != 2) {
+        puts(usage);
+        return -1;
+    }
+    int n = atoi(argv[1]);
+    if (n <= 0) {
+        puts(usage);
+        return -1;
+    }
+    for (int i=0; i < n; i++) {
+        if (i && (i % 80 == 0)) {
+            puts("");
+        }
+        putc('0' + (i % 10), stdout);
+    }
+    puts("");
+    return 0;
+}
+
+
+static const shell_command_t shell_commands[] = {
+    { "text",  "Generates long text for testing stdio buffer",  cmd_text },
+    { NULL, NULL, NULL }
+};
+
+
 int main(void)
 {
     (void) puts("RIOT USB CDC ACM shell test");
 
     char line_buf[SHELL_DEFAULT_BUFSIZE];
-    shell_run(NULL, line_buf, SHELL_DEFAULT_BUFSIZE);
+    shell_run(shell_commands, line_buf, SHELL_DEFAULT_BUFSIZE);
 
     return 0;
 }