LOONGSON: drm/radeon: Workaround radeon driver bug for Loongson

Radeon driver can not handle the interrupt is faster than DMA data, so
irq handler must update an old ih.rptr value in IH_RB_RPTR register to
enable interrupt again when interrupt is faster than DMA data.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Zhijie Zhang <zhangzhijie@loongson.cn>

Link: chenhuacai/linux@6266d00
Signed-off-by: Kexy Biscuit <kexybiscuit@aosc.io>
Signed-off-by: Mingcong Bai <jeffbai@aosc.io>

Author: chenhuacai

drivers/gpu/drm/radeon/cik.c

@@ -8093,6 +8093,7 @@ int cik_irq_process(struct radeon_device *rdev)
 	if (queue_thermal)
 		schedule_work(&rdev->pm.dpm.thermal.work);
 	rdev->ih.rptr = rptr;
+	WREG32(IH_RB_RPTR, rptr);
 	atomic_set(&rdev->ih.lock, 0);
 
 	/* make sure wptr hasn't changed while processing */

drivers/gpu/drm/radeon/evergreen.c

@@ -4927,6 +4927,7 @@ int evergreen_irq_process(struct radeon_device *rdev)
 	if (queue_thermal && rdev->pm.dpm_enabled)
 		schedule_work(&rdev->pm.dpm.thermal.work);
 	rdev->ih.rptr = rptr;
+	WREG32(IH_RB_RPTR, rptr);
 	atomic_set(&rdev->ih.lock, 0);
 
 	/* make sure wptr hasn't changed while processing */

drivers/gpu/drm/radeon/r600.c

@@ -4328,6 +4328,7 @@ int r600_irq_process(struct radeon_device *rdev)
 	if (queue_thermal && rdev->pm.dpm_enabled)
 		schedule_work(&rdev->pm.dpm.thermal.work);
 	rdev->ih.rptr = rptr;
+	WREG32(IH_RB_RPTR, rptr);
 	atomic_set(&rdev->ih.lock, 0);
 
 	/* make sure wptr hasn't changed while processing */

drivers/gpu/drm/radeon/si.c

@@ -6423,6 +6423,7 @@ int si_irq_process(struct radeon_device *rdev)
 	if (queue_thermal && rdev->pm.dpm_enabled)
 		schedule_work(&rdev->pm.dpm.thermal.work);
 	rdev->ih.rptr = rptr;
+	WREG32(IH_RB_RPTR, rptr);
 	atomic_set(&rdev->ih.lock, 0);
 
 	/* make sure wptr hasn't changed while processing */