From 4d79a1266d4cc3c967bc8823502466cad1ac8514 Mon Sep 17 00:00:00 2001
From: Ilia Levi <ilia.levi@intel.com>
Date: Tue, 10 Dec 2024 19:35:06 +0200
Subject: [PATCH] drm/xe: Make irq enabled flag atomic
The irq.enabled flag was protected by a spin lock (irq.lock).
By making it atomic we no longer need to wait for the spin lock in
irq handlers. This will become especially useful for MSI-X irq
handlers to prevent lock contention between different interrupts.
Signed-off-by: Ilia Levi <ilia.levi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210173506.202150-1-ilia.levi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
drivers/gpu/drm/xe/display/ext/i915_irq.c | 13 +---------
drivers/gpu/drm/xe/xe_device_types.h | 2 +-
drivers/gpu/drm/xe/xe_irq.c | 29 ++++++-----------------
3 files changed, 9 insertions(+), 35 deletions(-)
diff --git a/drivers/gpu/drm/xe/display/ext/i915_irq.c b/drivers/gpu/drm/xe/display/ext/i915_irq.c
index a7dbc6554d69..ac4cda2d81c7 100644
--- a/drivers/gpu/drm/xe/display/ext/i915_irq.c
+++ b/drivers/gpu/drm/xe/display/ext/i915_irq.c
@@ -53,18 +53,7 @@ void gen2_irq_init(struct intel_uncore *uncore, struct i915_irq_regs regs,
bool intel_irqs_enabled(struct xe_device *xe)
{
- /*
- * XXX: i915 has a racy handling of the irq.enabled, since it doesn't
- * lock its transitions. Because of that, the irq.enabled sometimes
- * is not read with the irq.lock in place.
- * However, the most critical cases like vblank and page flips are
- * properly using the locks.
- * We cannot take the lock in here or run any kind of assert because
- * of i915 inconsistency.
- * But at this point the xe irq is better protected against races,
- * although the full solution would be protecting the i915 side.
- */
- return xe->irq.enabled;
+ return atomic_read(&xe->irq.enabled);
}
void intel_synchronize_irq(struct xe_device *xe)
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 1373a222f5a5..ace22e35e769 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -347,7 +347,7 @@ struct xe_device {
spinlock_t lock;
/** @irq.enabled: interrupts enabled on this device */
- bool enabled;
+ atomic_t enabled;
} irq;
/** @ttm: ttm device */
diff --git a/drivers/gpu/drm/xe/xe_irq.c b/drivers/gpu/drm/xe/xe_irq.c
index 7bf7201529ac..1c509e66694d 100644
--- a/drivers/gpu/drm/xe/xe_irq.c
+++ b/drivers/gpu/drm/xe/xe_irq.c
@@ -348,12 +348,8 @@ static irqreturn_t xelp_irq_handler(int irq, void *arg)
unsigned long intr_dw[2];
u32 identity[32];
- spin_lock(&xe->irq.lock);
- if (!xe->irq.enabled) {
- spin_unlock(&xe->irq.lock);
+ if (!atomic_read(&xe->irq.enabled))
return IRQ_NONE;
- }
- spin_unlock(&xe->irq.lock);
master_ctl = xelp_intr_disable(xe);
if (!master_ctl) {
@@ -417,12 +413,8 @@ static irqreturn_t dg1_irq_handler(int irq, void *arg)
/* TODO: This really shouldn't be copied+pasted */
- spin_lock(&xe->irq.lock);
- if (!xe->irq.enabled) {
- spin_unlock(&xe->irq.lock);
+ if (!atomic_read(&xe->irq.enabled))
return IRQ_NONE;
- }
- spin_unlock(&xe->irq.lock);
master_tile_ctl = dg1_intr_disable(xe);
if (!master_tile_ctl) {
@@ -644,12 +636,8 @@ static irqreturn_t vf_mem_irq_handler(int irq, void *arg)
struct xe_tile *tile;
unsigned int id;
- spin_lock(&xe->irq.lock);
- if (!xe->irq.enabled) {
- spin_unlock(&xe->irq.lock);
+ if (!atomic_read(&xe->irq.enabled))
return IRQ_NONE;
- }
- spin_unlock(&xe->irq.lock);
for_each_tile(tile, xe, id)
xe_memirq_handler(&tile->memirq);
@@ -674,10 +662,9 @@ static void irq_uninstall(void *arg)
struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
int irq;
- if (!xe->irq.enabled)
+ if (!atomic_xchg(&xe->irq.enabled, 0))
return;
- xe->irq.enabled = false;
xe_irq_reset(xe);
irq = pci_irq_vector(pdev, 0);
@@ -724,7 +711,7 @@ int xe_irq_install(struct xe_device *xe)
return err;
}
- xe->irq.enabled = true;
+ atomic_set(&xe->irq.enabled, 1);
xe_irq_postinstall(xe);
@@ -744,9 +731,7 @@ void xe_irq_suspend(struct xe_device *xe)
{
int irq = to_pci_dev(xe->drm.dev)->irq;
- spin_lock_irq(&xe->irq.lock);
- xe->irq.enabled = false; /* no new irqs */
- spin_unlock_irq(&xe->irq.lock);
+ atomic_set(&xe->irq.enabled, 0); /* no new irqs */
synchronize_irq(irq); /* flush irqs */
xe_irq_reset(xe); /* turn irqs off */
@@ -762,7 +747,7 @@ void xe_irq_resume(struct xe_device *xe)
* 1. no irq will arrive before the postinstall
* 2. display is not yet resumed
*/
- xe->irq.enabled = true;
+ atomic_set(&xe->irq.enabled, 1);
xe_irq_reset(xe);
xe_irq_postinstall(xe); /* turn irqs on */
--
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