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Subject[PATCH 3/3] drm/rockchip: Don't use spin_lock_irqsave in interrupt context
Date
The rockchip DRM driver is quite careful to disable interrupts
when taking a lock that is also taken in interrupt context,
which is a good thing.

What is a bit over the top is to use spin_lock_irqsave when
already in interrupt context, as you cannot take another
interrupt again, and disabling interrupt is just pure
overhead.

Switching to the non _irqsave version in interrupt context is
more logical, and less heavy handed.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index f2bde1c76bbe..48d27f6fb16d 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1160,15 +1160,14 @@ static void vop_handle_vblank(struct vop *vop)
{
struct drm_device *drm = vop->drm_dev;
struct drm_crtc *crtc = &vop->crtc;
- unsigned long flags;

- spin_lock_irqsave(&drm->event_lock, flags);
+ spin_lock(&drm->event_lock);
if (vop->event) {
drm_crtc_send_vblank_event(crtc, vop->event);
drm_crtc_vblank_put(crtc);
vop->event = NULL;
}
- spin_unlock_irqrestore(&drm->event_lock, flags);
+ spin_unlock(&drm->event_lock);

if (test_and_clear_bit(VOP_PENDING_FB_UNREF, &vop->pending))
drm_flip_work_commit(&vop->fb_unref_work, system_unbound_wq);
@@ -1179,21 +1178,20 @@ static irqreturn_t vop_isr(int irq, void *data)
struct vop *vop = data;
struct drm_crtc *crtc = &vop->crtc;
uint32_t active_irqs;
- unsigned long flags;
int ret = IRQ_NONE;

/*
* interrupt register has interrupt status, enable and clear bits, we
* must hold irq_lock to avoid a race with enable/disable_vblank().
*/
- spin_lock_irqsave(&vop->irq_lock, flags);
+ spin_lock(&vop->irq_lock);

active_irqs = VOP_INTR_GET_TYPE(vop, status, INTR_MASK);
/* Clear all active interrupt sources */
if (active_irqs)
VOP_INTR_SET_TYPE(vop, clear, active_irqs, 1);

- spin_unlock_irqrestore(&vop->irq_lock, flags);
+ spin_unlock(&vop->irq_lock);

/* This is expected for vop iommu irqs, since the irq is shared */
if (!active_irqs)
--
2.14.2
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