https://git.qemu.org/?p=qemu.git;a=commitdiff;h=6670b494fdb23f74ecd9b
** Changed in: qemu
Status: In Progress => Fix Committed
--
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https://bugs.launchpad.net/bugs/1760262
Title:
cmsdk-apb-uart doesn't appear to clear interrupt flags
Status in QEMU:
Fix Committed
Bug description:
I have been writing a small operating system and using QEMU emulating
the mps2-an385 board for some of my testing.
During development of the uart driver I observed some odd behaviour
with the TX interrupt -- writing a '1' to bit 0 of the INTCLEAR
register doesn't clear the TX interrupt flag, and the interrupt fires
continuously.
It's possible that I have an error somewhere in my code, but after
inspecting the QEMU source it does appear to be a QEMU bug. I applied
the following patch and it solved my issue:
From 9875839c144fa60a3772f16ae44d32685f9328aa Mon Sep 17 00:00:00 2001
From: Patrick Oppenlander <patrick.oppenlan...@gmail.com>
Date: Sat, 31 Mar 2018 15:10:28 +1100
Subject: [PATCH] hw/char/cmsdk-apb-uart: fix clearing of interrupt flags
---
hw/char/cmsdk-apb-uart.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/hw/char/cmsdk-apb-uart.c b/hw/char/cmsdk-apb-uart.c
index 1ad1e14295..64991bd9d7 100644
--- a/hw/char/cmsdk-apb-uart.c
+++ b/hw/char/cmsdk-apb-uart.c
@@ -274,6 +274,7 @@ static void uart_write(void *opaque, hwaddr offset,
uint64_t value,
* is then reflected into the intstatus value by the update
function).
*/
s->state &= ~(value & (R_INTSTATUS_TXO_MASK | R_INTSTATUS_RXO_MASK));
+ s->intstatus &= ~(value & ~(R_INTSTATUS_TXO_MASK |
R_INTSTATUS_RXO_MASK));
cmsdk_apb_uart_update(s);
break;
case A_BAUDDIV:
--
2.16.2
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