From 7a3f292c8316239182f30fa8f3a5e5a14cca587c Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Wed, 17 Aug 2022 23:41:30 +0200
Subject: amd64/rtl8139: don't trust the card to have packets available on irq

---
 src/kernel/arch/amd64/driver/rtl8139.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

(limited to 'src/kernel/arch/amd64/driver')

diff --git a/src/kernel/arch/amd64/driver/rtl8139.c b/src/kernel/arch/amd64/driver/rtl8139.c
index 2438002..e50fb63 100644
--- a/src/kernel/arch/amd64/driver/rtl8139.c
+++ b/src/kernel/arch/amd64/driver/rtl8139.c
@@ -91,7 +91,9 @@ void rtl8139_irq(void) {
 	}
 	status &= 1;
 
-	do {
+	/* bit 0 of cmd - Rx Buffer Empty
+	 * not a do while() because sometimes the bit is empty on IRQ. no clue why. */
+	while (!(port_in8(iobase + CMD) & 1)) {
 		if (blocked_on) {
 			accept(blocked_on);
 			blocked_on = blocked_on->postqueue_next;
@@ -99,7 +101,7 @@ void rtl8139_irq(void) {
 			rx_irq_enable(false);
 			break;
 		}
-	} while (!(port_in8(iobase + CMD) & 1)); /* bit 0 - Rx Buffer Empty */
+	}
 
 	//kprintf("rxpos %x cbr %x\n", rxpos, port_in16(iobase + CBR));
 	port_out16(iobase + INTRSTATUS, status);
@@ -170,7 +172,7 @@ static void accept(struct vfs_request *req) {
 			ret = try_rx(req->caller->pages, req->output.buf, req->output.len);
 			if (ret == WAIT) {
 				// TODO this is a pretty common pattern in drivers, try to make it unneeded
-				// TODO invalid assert, fails on nmap
+				// TODO those asserts should actually be regular panic checks
 				assert(!req->postqueue_next);
 				struct vfs_request **slot = &blocked_on;
 				while (*slot) slot = &(*slot)->postqueue_next;
-- 
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