From: Keith Packard <keithp@keithp.com>
Date: Wed, 27 Jun 2012 21:35:56 +0000 (-0700)
Subject: altos: reorder stm USB state stores to avoid races
X-Git-Tag: 1.0.9.6~13
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=e63d624f9670b5e2e002fcd5f24b80cf7f1effdf

altos: reorder stm USB state stores to avoid races

Must set ao_usb_in_pending before telling USB about new data or an
interrupt could arrive at the wrong time to clear it.

Same for ao_usb_in_flushed.

Without these changes, I've seen the USB bus lock up on occasion,
waiting for an IN packet to consume data, but with no IN data pending
in the hardware.

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/stm/ao_usb_stm.c b/src/stm/ao_usb_stm.c
index c093f526..4f37a7d9 100644
--- a/src/stm/ao_usb_stm.c
+++ b/src/stm/ao_usb_stm.c
@@ -792,10 +792,10 @@ static void
 ao_usb_in_send(void)
 {
 	debug ("send %d\n", ao_usb_tx_count);
+	ao_usb_in_pending = 1;
 	ao_usb_write(ao_usb_tx_buffer, ao_usb_in_tx_buffer, 0, ao_usb_tx_count);
 	ao_usb_bdt[AO_USB_IN_EPR].single.count_tx = ao_usb_tx_count;
 	ao_usb_set_stat_tx(AO_USB_IN_EPR, STM_USB_EPR_STAT_TX_VALID);
-	ao_usb_in_pending = 1;
 	ao_usb_tx_count = 0;
 }
 
@@ -848,12 +848,12 @@ ao_usb_putchar(char c) __critical __reentrant
 
 	ao_usb_in_wait();
 
+	ao_usb_in_flushed = 0;
 	ao_usb_tx_buffer[ao_usb_tx_count++] = (uint8_t) c;
 
 	/* Send the packet when full */
 	if (ao_usb_tx_count == AO_USB_IN_SIZE)
 		ao_usb_in_send();
-	ao_usb_in_flushed = 0;
 }
 
 static void