Unverified Commit 4d79a126 authored by Ilia Levi's avatar Ilia Levi Committed by Rodrigo Vivi
Browse files

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: default avatarIlia Levi <ilia.levi@intel.com>
Reviewed-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210173506.202150-1-ilia.levi@intel.com


Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent 3fcf68d7

drivers/gpu/drm/xe/display/ext/i915_irq.c

+1 −12
Original line number Diff line number Diff line
@@ -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)

drivers/gpu/drm/xe/xe_device_types.h

+1 −1
Original line number Diff line number Diff line
@@ -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 */

drivers/gpu/drm/xe/xe_irq.c

+7 −22
Original line number Diff line number Diff line
@@ -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 */