accel/ivpu/40xx: Fix buttress interrupt handling

Buttress spec requires that the interrupt status is cleared at
the source first (before clearing MTL_BUTTRESS_INTERRUPT_STAT),
that implies that we have to mask out the global interrupt while
handling buttress interrupts.

Fixes: 79cdc56c ("accel/ivpu: Add initial support for VPU 4")
Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230822095238.3722815-1-stanislaw.gruszka@linux.intel.com

drivers/accel/ivpu/ivpu_hw_40xx.c

@@ -1046,7 +1046,8 @@ static irqreturn_t ivpu_hw_40xx_irqb_handler(struct ivpu_device *vdev, int irq)
 	if (status == 0)
 		return IRQ_NONE;
 
-	REGB_WR32(VPU_40XX_BUTTRESS_INTERRUPT_STAT, status);
+	/* Disable global interrupt before handling local buttress interrupts */
+	REGB_WR32(VPU_40XX_BUTTRESS_GLOBAL_INT_MASK, 0x1);
 
 	if (REG_TEST_FLD(VPU_40XX_BUTTRESS_INTERRUPT_STAT, FREQ_CHANGE, status))
 		ivpu_dbg(vdev, IRQ, "FREQ_CHANGE");
@@ -1092,6 +1093,12 @@ static irqreturn_t ivpu_hw_40xx_irqb_handler(struct ivpu_device *vdev, int irq)
 		schedule_recovery = true;
 	}
 
+	/* This must be done after interrupts are cleared at the source. */
+	REGB_WR32(VPU_40XX_BUTTRESS_INTERRUPT_STAT, status);
+
+	/* Re-enable global interrupt */
+	REGB_WR32(VPU_40XX_BUTTRESS_GLOBAL_INT_MASK, 0x0);
+
 	if (schedule_recovery)
 		ivpu_pm_schedule_recovery(vdev);