[PATCH] drm/amdgpu: fix NULL pointer crash on navi10 headless SKU

[Tianci Yin]

From: "Tianci.Yin" <tianci.yin at amd.com>

The crash caused by the NULL pointer of
adev->ddev.mode_config.funcs in drm_kms_helper_hotplug_event(),
but this function should not be called on headless SKU.

Fix the mismatch between the return value of
amdgpu_device_has_dc_support() and the real DCN supporting
state to avoid calling to drm_kms_helper_hotplug_event()
in amdgpu_device_resume().

Change-Id: I3a3d387e6ab5b774abb3911ea1bf6de60797759d
Signed-off-by: Tianci.Yin <tianci.yin at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c  | 10 ++++++++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_display.c |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c     |  2 +-
 drivers/gpu/drm/amd/amdgpu/nv.c             |  2 +-
 drivers/gpu/drm/amd/amdgpu/nv.h             |  1 +
 6 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index ba65d4f2ab67..f0183271456f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1090,7 +1090,7 @@ void amdgpu_device_indirect_wreg64(struct amdgpu_device *adev,
 				   u32 pcie_index, u32 pcie_data,
 				   u32 reg_addr, u64 reg_data);
 
-bool amdgpu_device_asic_has_dc_support(enum amd_asic_type asic_type);
+bool amdgpu_device_asic_has_dc_support(enum amd_asic_type asic_type, struct pci_dev *pdev);
 bool amdgpu_device_has_dc_support(struct amdgpu_device *adev);
 
 int emu_soc_asic_init(struct amdgpu_device *adev);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 1fe850e0a94d..323ed69032a7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -2960,11 +2960,12 @@ static void amdgpu_device_detect_sriov_bios(struct amdgpu_device *adev)
  * amdgpu_device_asic_has_dc_support - determine if DC supports the asic
  *
  * @asic_type: AMD asic type
+ * @pdev: pointer to pci_dev instance
  *
  * Check if there is DC (new modesetting infrastructre) support for an asic.
  * returns true if DC has support, false if not.
  */
-bool amdgpu_device_asic_has_dc_support(enum amd_asic_type asic_type)
+bool amdgpu_device_asic_has_dc_support(enum amd_asic_type asic_type, struct pci_dev *pdev)
 {
 	switch (asic_type) {
 #if defined(CONFIG_DRM_AMD_DC)
@@ -3000,9 +3001,14 @@ bool amdgpu_device_asic_has_dc_support(enum amd_asic_type asic_type)
 	case CHIP_VEGA20:
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 	case CHIP_RAVEN:
+		return amdgpu_dc != 0;
 	case CHIP_NAVI10:
 	case CHIP_NAVI14:
 	case CHIP_NAVI12:
+		if (nv_is_headless_sku(pdev))
+			return false;
+		else
+			return amdgpu_dc != 0;
 	case CHIP_RENOIR:
 #endif
 #if defined(CONFIG_DRM_AMD_DC_DCN3_0)
@@ -3033,7 +3039,7 @@ bool amdgpu_device_has_dc_support(struct amdgpu_device *adev)
 	if (amdgpu_sriov_vf(adev) || adev->enable_virtual_display)
 		return false;
 
-	return amdgpu_device_asic_has_dc_support(adev->asic_type);
+	return amdgpu_device_asic_has_dc_support(adev->asic_type, adev->pdev);
 }
 
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index 9e92d2a070ac..97014458d7de 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -516,7 +516,7 @@ uint32_t amdgpu_display_supported_domains(struct amdgpu_device *adev,
 	 */
 	if ((bo_flags & AMDGPU_GEM_CREATE_CPU_GTT_USWC) &&
 	    amdgpu_bo_support_uswc(bo_flags) &&
-	    amdgpu_device_asic_has_dc_support(adev->asic_type)) {
+	    amdgpu_device_asic_has_dc_support(adev->asic_type, adev->pdev)) {
 		switch (adev->asic_type) {
 		case CHIP_CARRIZO:
 		case CHIP_STONEY:
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 4b78ecfd35f7..b23110241267 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -1117,7 +1117,7 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
 	bool supports_atomic = false;
 
 	if (!amdgpu_virtual_display &&
-	    amdgpu_device_asic_has_dc_support(flags & AMD_ASIC_MASK))
+	    amdgpu_device_asic_has_dc_support(flags & AMD_ASIC_MASK, pdev))
 		supports_atomic = true;
 
 	if ((flags & AMD_EXP_HW_SUPPORT) && !amdgpu_exp_hw_support) {
diff --git a/drivers/gpu/drm/amd/amdgpu/nv.c b/drivers/gpu/drm/amd/amdgpu/nv.c
index 026e0a8fd526..97446ae75b0b 100644
--- a/drivers/gpu/drm/amd/amdgpu/nv.c
+++ b/drivers/gpu/drm/amd/amdgpu/nv.c
@@ -493,7 +493,7 @@ void nv_set_virt_ops(struct amdgpu_device *adev)
 	adev->virt.ops = &xgpu_nv_virt_ops;
 }
 
-static bool nv_is_headless_sku(struct pci_dev *pdev)
+bool nv_is_headless_sku(struct pci_dev *pdev)
 {
 	if ((pdev->device == 0x731E &&
 	    (pdev->revision == 0xC6 || pdev->revision == 0xC7)) ||
diff --git a/drivers/gpu/drm/amd/amdgpu/nv.h b/drivers/gpu/drm/amd/amdgpu/nv.h
index 515d67bf249f..7880ad0073c9 100644
--- a/drivers/gpu/drm/amd/amdgpu/nv.h
+++ b/drivers/gpu/drm/amd/amdgpu/nv.h
@@ -29,6 +29,7 @@
 void nv_grbm_select(struct amdgpu_device *adev,
 		    u32 me, u32 pipe, u32 queue, u32 vmid);
 void nv_set_virt_ops(struct amdgpu_device *adev);
+bool nv_is_headless_sku(struct pci_dev *pdev);
 int nv_set_ip_blocks(struct amdgpu_device *adev);
 int navi10_reg_base_init(struct amdgpu_device *adev);
 int navi14_reg_base_init(struct amdgpu_device *adev);
-- 
2.17.1