[PATCH v2] irqchip: gic-v3: Handle failure case of CPU enters low power state

[PATCH v2] irqchip: gic-v3: Handle failure case of CPU enters low power state

[Yogesh Lal]

Adding a new condition in gic_cpu_pm_notifier to address instances
where the CPU fails to enter low power mode (CPU_PM_ENTER_FAILED).
The CPU_PM framework signals CPU_PM_ENTER_FAILED upon such failures.

When the CPU attempts to enter low power mode, it disables the
redistributor and Group 1 interrupts and reinitializes the system
registers upon wakeup.

In case of failure while entering low power mode, it is necessary
to re-enable the redistributor and Group 1 interrupts to restore
normal operation.

Signed-off-by: Yogesh Lal <quic_ylal@quicinc.com>
---
 drivers/irqchip/irq-gic-v3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

---
Changes in V2:

* Updating the commit message
* Link to V1: https://lore.kernel.org/all/1671734140-15935-1-git-send-email-quic_ylal@quicinc.com/
---

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index c19083bfb943..2a99ca5c3f1d 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1495,7 +1495,7 @@ static int gic_retrigger(struct irq_data *data)
 static int gic_cpu_pm_notifier(struct notifier_block *self,
 			       unsigned long cmd, void *v)
 {
-	if (cmd == CPU_PM_EXIT) {
+	if (cmd == CPU_PM_EXIT || cmd == CPU_PM_ENTER_FAILED) {
 		if (gic_dist_security_disabled())
 			gic_enable_redist(true);
 		gic_cpu_sys_reg_init();
-- 
2.34.1

Re: [PATCH v2] irqchip: gic-v3: Handle failure case of CPU enters low power state

[Marc Zyngier]

On Fri, 20 Dec 2024 09:39:07 +0000,
Yogesh Lal <quic_ylal@quicinc.com> wrote:
> 
> Adding a new condition in gic_cpu_pm_notifier to address instances
> where the CPU fails to enter low power mode (CPU_PM_ENTER_FAILED).
> The CPU_PM framework signals CPU_PM_ENTER_FAILED upon such failures.
> 
> When the CPU attempts to enter low power mode, it disables the
> redistributor and Group 1 interrupts and reinitializes the system
> registers upon wakeup.
> 
> In case of failure while entering low power mode, it is necessary
> to re-enable the redistributor and Group 1 interrupts to restore
> normal operation.
> 
> Signed-off-by: Yogesh Lal <quic_ylal@quicinc.com>

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

[tip: irq/urgent] irqchip/gic-v3: Handle CPU_PM_ENTER_FAILED correctly

[tip-bot2 for Yogesh Lal]

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     0d62a49ab55c99e8deb4593b8d9f923de1ab5c18
Gitweb:        https://git.kernel.org/tip/0d62a49ab55c99e8deb4593b8d9f923de1ab5c18
Author:        Yogesh Lal <quic_ylal@quicinc.com>
AuthorDate:    Fri, 20 Dec 2024 15:09:07 +05:30
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 15 Jan 2025 09:42:44 +01:00

irqchip/gic-v3: Handle CPU_PM_ENTER_FAILED correctly

When a CPU attempts to enter low power mode, it disables the redistributor
and Group 1 interrupts and reinitializes the system registers upon wakeup.

If the transition into low power mode fails, then the CPU_PM framework
invokes the PM notifier callback with CPU_PM_ENTER_FAILED to allow the
drivers to undo the state changes.

The GIC V3 driver ignores CPU_PM_ENTER_FAILED, which leaves the GIC in
disabled state.

Handle CPU_PM_ENTER_FAILED in the same way as CPU_PM_EXIT to restore normal
operation.

[ tglx: Massage change log, add Fixes tag ]

Fixes: 3708d52fc6bb ("irqchip: gic-v3: Implement CPU PM notifier")
Signed-off-by: Yogesh Lal <quic_ylal@quicinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20241220093907.2747601-1-quic_ylal@quicinc.com
---
 drivers/irqchip/irq-gic-v3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 79d8cc8..76dce0a 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1522,7 +1522,7 @@ static int gic_retrigger(struct irq_data *data)
 static int gic_cpu_pm_notifier(struct notifier_block *self,
 			       unsigned long cmd, void *v)
 {
-	if (cmd == CPU_PM_EXIT) {
+	if (cmd == CPU_PM_EXIT || cmd == CPU_PM_ENTER_FAILED) {
 		if (gic_dist_security_disabled())
 			gic_enable_redist(true);
 		gic_cpu_sys_reg_enable();