[PATCH] drm/amdgpu: Clear doorbell interrupt status for Sienna Cichlid

[Chengzhe Liu]

On Sienna Cichlid, in pass-through mode, if we unload the driver in BACO
mode(RTPM), then the kernel would receive thousands of interrupts.
That's because there is doorbell monitor interrupt on BIF, so KVM keeps
injecting interrupts to the guest VM. So we should clear the doorbell
interrupt status after BACO exit.

v2: Modify coding style and commit message

Signed-off-by: Chengzhe Liu <ChengZhe.Liu at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  4 ++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h   |  1 +
 drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c     | 21 +++++++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 37fa199be8b3..92f73d2bbfc9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -5265,6 +5265,10 @@ int amdgpu_device_baco_exit(struct drm_device *dev)
 	    adev->nbio.funcs->enable_doorbell_interrupt)
 		adev->nbio.funcs->enable_doorbell_interrupt(adev, true);
 
+	if (amdgpu_passthrough(adev) &&
+	    adev->nbio.funcs->clear_doorbell_interrupt)
+		adev->nbio.funcs->clear_doorbell_interrupt(adev);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h
index 45295dce5c3e..843052205bd5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h
@@ -95,6 +95,7 @@ struct amdgpu_nbio_funcs {
 	void (*program_aspm)(struct amdgpu_device *adev);
 	void (*apply_lc_spc_mode_wa)(struct amdgpu_device *adev);
 	void (*apply_l1_link_width_reconfig_wa)(struct amdgpu_device *adev);
+	void (*clear_doorbell_interrupt)(struct amdgpu_device *adev);
 };
 
 struct amdgpu_nbio {
diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
index 7b79eeaa88aa..b184b656b9b6 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
@@ -508,6 +508,26 @@ static void nbio_v2_3_apply_l1_link_width_reconfig_wa(struct amdgpu_device *adev
 	WREG32_PCIE(smnPCIE_LC_LINK_WIDTH_CNTL, reg_data);
 }
 
+static void nbio_v2_3_clear_doorbell_interrupt(struct amdgpu_device *adev)
+{
+	uint32_t reg, reg_data;
+
+	if (adev->asic_type != CHIP_SIENNA_CICHLID)
+		return;
+
+	reg = RREG32_SOC15(NBIO, 0, mmBIF_RB_CNTL);
+
+	/* Clear Interrupt Status
+	 */
+	if ((reg & BIF_RB_CNTL__RB_ENABLE_MASK) == 0) {
+		reg = RREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL);
+		if (reg & BIF_DOORBELL_INT_CNTL__DOORBELL_INTERRUPT_STATUS_MASK) {
+			reg_data = 1 << BIF_DOORBELL_INT_CNTL__DOORBELL_INTERRUPT_CLEAR__SHIFT;
+			WREG32_SOC15(NBIO, 0, mmBIF_DOORBELL_INT_CNTL, reg_data);
+		}
+	}
+}
+
 const struct amdgpu_nbio_funcs nbio_v2_3_funcs = {
 	.get_hdp_flush_req_offset = nbio_v2_3_get_hdp_flush_req_offset,
 	.get_hdp_flush_done_offset = nbio_v2_3_get_hdp_flush_done_offset,
@@ -531,4 +551,5 @@ const struct amdgpu_nbio_funcs nbio_v2_3_funcs = {
 	.program_aspm =  nbio_v2_3_program_aspm,
 	.apply_lc_spc_mode_wa = nbio_v2_3_apply_lc_spc_mode_wa,
 	.apply_l1_link_width_reconfig_wa = nbio_v2_3_apply_l1_link_width_reconfig_wa,
+	.clear_doorbell_interrupt = nbio_v2_3_clear_doorbell_interrupt,
 };
-- 
2.25.1