From 0aa5e7500047d869cc78e8914fc08b5d6a3f5994 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Sun, 7 Jun 2015 23:48:07 +0100
Subject: [PATCH] stmhal: Break immediately from USB CDC busy wait loop if IRQs
disabled.
If IRQs are disabled then the USB CDC buffer will never be
drained/filled and the sys-tick timer will never increase, so we should
not busy wait in this case.
---
stmhal/usbd_cdc_interface.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/stmhal/usbd_cdc_interface.c b/stmhal/usbd_cdc_interface.c
index 8b088660f..2bb8ddb95 100644
--- a/stmhal/usbd_cdc_interface.c
+++ b/stmhal/usbd_cdc_interface.c
@@ -42,6 +42,7 @@
#include "pendsv.h"
#include "py/obj.h"
+#include "irq.h"
#include "timer.h"
#include "usb.h"
@@ -417,6 +418,10 @@ int USBD_CDC_Tx(const uint8_t *buf, uint32_t len, uint32_t timeout) {
// timeout
return i;
}
+ if (query_irq() == IRQ_STATE_DISABLED) {
+ // IRQs disabled so buffer will never be drained; return immediately
+ return i;
+ }
__WFI(); // enter sleep mode, waiting for interrupt
}
@@ -444,6 +449,10 @@ void USBD_CDC_TxAlways(const uint8_t *buf, uint32_t len) {
// (wraparound of tick is taken care of by 2's complement arithmetic).
uint32_t start = HAL_GetTick();
while (((UserTxBufPtrIn + 1) & (APP_TX_DATA_SIZE - 1)) == UserTxBufPtrOut && HAL_GetTick() - start <= 500) {
+ if (query_irq() == IRQ_STATE_DISABLED) {
+ // IRQs disabled so buffer will never be drained; exit loop
+ break;
+ }
__WFI(); // enter sleep mode, waiting for interrupt
}
@@ -489,6 +498,10 @@ int USBD_CDC_Rx(uint8_t *buf, uint32_t len, uint32_t timeout) {
// timeout
return i;
}
+ if (query_irq() == IRQ_STATE_DISABLED) {
+ // IRQs disabled so buffer will never be filled; return immediately
+ return i;
+ }
__WFI(); // enter sleep mode, waiting for interrupt
}
--
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