qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[PATCH-for 5.2?] hw/core/ressetable: fix reset count decrement


From: Damien Hedde
Subject: [PATCH-for 5.2?] hw/core/ressetable: fix reset count decrement
Date: Wed, 2 Dec 2020 17:40:55 +0100

The reset count was only decremented if the device was in a single
reset.

Also move the decrement before calling the exit phase method to fix
problem of reset state evaluation during that call. Update the doc
accordingly.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Fixes: 1905297 ("Zynq7000 UART clock reset initialization", 2020-11-23)
Reported-by: Michael Peter <michael.peter@hensoldt-cyber.com>
--

Hi all,

While looking at the bug reported by Michael and his patch. I found another
bug. Apparently I forgot to decrement the reset count if there was several
reset at the same time.

This patch fixes that.

I also moved the place of the decrement: before calling the exit phase method.
it globally fixes Michael's reported bug, as I think it will avoid some boiler
plate code in every exit phase method we do.

Only other place where the reset state is checked is in the
hw/char/cadence-uart.c so it does not have high impact.

I'm not sure if this meets the condition for 5.2 as it changes a documented
feature. In that case we can just accept Michael solution and I'll fix the
rest later.

Here's the pointer for the bug and michael's patch.
https://lists.nongnu.org/archive/html/qemu-devel/2020-11/msg05786.html
https://lists.nongnu.org/archive/html/qemu-devel/2020-11/msg06105.html

Damien
---
 docs/devel/reset.rst | 6 +++---
 hw/core/resettable.c | 3 +--
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/docs/devel/reset.rst b/docs/devel/reset.rst
index abea1102dc..021a7277a2 100644
--- a/docs/devel/reset.rst
+++ b/docs/devel/reset.rst
@@ -210,9 +210,9 @@ Polling the reset state
 Resettable interface provides the ``resettable_is_in_reset()`` function.
 This function returns true if the object parameter is currently under reset.
 
-An object is under reset from the beginning of the *init* phase to the end of
-the *exit* phase. During all three phases, the function will return that the
-object is in reset.
+An object is under reset from the beginning of the *init* phase to the *exit*
+phase. During *init* and *hold* phase only, the function will return that the
+object is in reset. The state is changed just before calling the *exit* method.
 
 This function may be used if the object behavior has to be adapted
 while in reset state. For example if a device has an irq input,
diff --git a/hw/core/resettable.c b/hw/core/resettable.c
index 96a99ce39e..c3df75c6ba 100644
--- a/hw/core/resettable.c
+++ b/hw/core/resettable.c
@@ -201,12 +201,11 @@ static void resettable_phase_exit(Object *obj, void 
*opaque, ResetType type)
     resettable_child_foreach(rc, obj, resettable_phase_exit, NULL, type);
 
     assert(s->count > 0);
-    if (s->count == 1) {
+    if (--s->count == 0) {
         trace_resettable_phase_exit_exec(obj, obj_typename, !!rc->phases.exit);
         if (rc->phases.exit && !resettable_get_tr_func(rc, obj)) {
             rc->phases.exit(obj);
         }
-        s->count = 0;
     }
     s->exit_phase_in_progress = false;
     trace_resettable_phase_exit_end(obj, obj_typename, s->count);
-- 
2.29.2




reply via email to

[Prev in Thread] Current Thread [Next in Thread]