[PATCH 4.14 158/217] drm/armada: fix irq handling

Greg Kroah-Hartman
2018-08-23T08:30:57Z

From: Russell King <rmk+kernel@armlinux.org.uk>

[ Upstream commit 92298c1cd8e8a6b56322b602ad72b54e6237631d ]

Add the missing locks to the IRQ enable/disable paths, and fix a comment
in the interrupt handler: reading the ISR clears down the status bits,
but does not reset the interrupt so it can signal again. That seems to
require a write.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/armada/armada_crtc.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/armada/armada_crtc.c
+++ b/drivers/gpu/drm/armada/armada_crtc.c
@@ -483,8 +483,9 @@ static irqreturn_t armada_drm_irq(int ir
u32 v, stat = readl_relaxed(dcrtc->base + LCD_SPU_IRQ_ISR);

/*
- * This is rediculous - rather than writing bits to clear, we
- * have to set the actual status register value. This is racy.
+ * Reading the ISR appears to clear bits provided CLEAN_SPU_IRQ_ISR
+ * is set. Writing has some other effect to acknowledge the IRQ -
+ * without this, we only get a single IRQ.
*/
writel_relaxed(0, dcrtc->base + LCD_SPU_IRQ_ISR);

@@ -1104,16 +1105,22 @@ armada_drm_crtc_set_property(struct drm_
static int armada_drm_crtc_enable_vblank(struct drm_crtc *crtc)
{
struct armada_crtc *dcrtc = drm_to_armada_crtc(crtc);
+ unsigned long flags;

+ spin_lock_irqsave(&dcrtc->irq_lock, flags);
armada_drm_crtc_enable_irq(dcrtc, VSYNC_IRQ_ENA);
+ spin_unlock_irqrestore(&dcrtc->irq_lock, flags);
return 0;
}

static void armada_drm_crtc_disable_vblank(struct drm_crtc *crtc)
{
struct armada_crtc *dcrtc = drm_to_armada_crtc(crtc);
+ unsigned long flags;

+ spin_lock_irqsave(&dcrtc->irq_lock, flags);
armada_drm_crtc_disable_irq(dcrtc, VSYNC_IRQ_ENA);
+ spin_unlock_irqrestore(&dcrtc->irq_lock, flags);
}

static const struct drm_crtc_funcs armada_crtc_funcs = {
@@ -1221,6 +1228,7 @@ static int armada_drm_crtc_create(struct
CFG_PDWN64x66, dcrtc->base + LCD_SPU_SRAM_PARA1);
writel_relaxed(0x2032ff81, dcrtc->base + LCD_SPU_DMA_CTRL1);
writel_relaxed(dcrtc->irq_ena, dcrtc->base + LCD_SPU_IRQ_ENA);
+ readl_relaxed(dcrtc->base + LCD_SPU_IRQ_ISR);
writel_relaxed(0, dcrtc->base + LCD_SPU_IRQ_ISR);

ret = devm_request_irq(dev, irq, armada_drm_irq, 0, "armada_drm_crtc",