[PATCH 4.8 25/35] drm/radeon: fix check for port PM availability

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Deucher <alexander.deucher@xxxxxxx>

commit bcfdd5d5105087e6f33dfeb08a1ca6b2c0287b61 upstream.

The ATPX method does not always exist on the dGPU, it may be located at
the iGPU. The parent device of the iGPU is the root port for which
bridge_d3 is false. This accidentally enables the legacy PM method which
conflicts with port PM and prevented the dGPU from powering on.

Ported from amdgpu commit:
drm/amdgpu: fix check for port PM availability
from Peter Wu.

Fixes: d3ac31f3b4bf9fad (drm/radeon: fix power state when port pm is unavailable (v2))
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Peter Wu <peter@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/radeon/radeon_atpx_handler.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/radeon/radeon_atpx_handler.c
+++ b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
@@ -474,7 +474,6 @@ static int radeon_atpx_power_state(enum
  */
 static bool radeon_atpx_pci_probe_handle(struct pci_dev *pdev)
 {
-	struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
 	acpi_handle dhandle, atpx_handle;
 	acpi_status status;
 
@@ -488,7 +487,6 @@ static bool radeon_atpx_pci_probe_handle
 
 	radeon_atpx_priv.dhandle = dhandle;
 	radeon_atpx_priv.atpx.handle = atpx_handle;
-	radeon_atpx_priv.bridge_pm_usable = parent_pdev && parent_pdev->bridge_d3;
 	return true;
 }
 
@@ -550,11 +548,16 @@ static bool radeon_atpx_detect(void)
 	struct pci_dev *pdev = NULL;
 	bool has_atpx = false;
 	int vga_count = 0;
+	bool d3_supported = false;
+	struct pci_dev *parent_pdev;
 
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
 		vga_count++;
 
 		has_atpx |= (radeon_atpx_pci_probe_handle(pdev) == true);
+
+		parent_pdev = pci_upstream_bridge(pdev);
+		d3_supported |= parent_pdev && parent_pdev->bridge_d3;
 	}
 
 	/* some newer PX laptops mark the dGPU as a non-VGA display device */
@@ -562,6 +565,9 @@ static bool radeon_atpx_detect(void)
 		vga_count++;
 
 		has_atpx |= (radeon_atpx_pci_probe_handle(pdev) == true);
+
+		parent_pdev = pci_upstream_bridge(pdev);
+		d3_supported |= parent_pdev && parent_pdev->bridge_d3;
 	}
 
 	if (has_atpx && vga_count == 2) {
@@ -569,6 +575,7 @@ static bool radeon_atpx_detect(void)
 		printk(KERN_INFO "vga_switcheroo: detected switching method %s handle\n",
 		       acpi_method_name);
 		radeon_atpx_priv.atpx_detected = true;
+		radeon_atpx_priv.bridge_pm_usable = d3_supported;
 		radeon_atpx_init();
 		return true;
 	}