drm/radeon/kms: auto detect pcie link speed from root port

This check the root ports supported link speeds and enables
GEN2 mode if the 5.0 GT link speed is available.

The first 3.0 cards are SI so they will probably need more investigation.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/evergreen.c

@@ -3421,7 +3421,8 @@ void evergreen_fini(struct radeon_device *rdev)
 
 void evergreen_pcie_gen2_enable(struct radeon_device *rdev)
 {
-	u32 link_width_cntl, speed_cntl;
+	u32 link_width_cntl, speed_cntl, mask;
+	int ret;
 
 	if (radeon_pcie_gen2 == 0)
 		return;
@@ -3436,6 +3437,15 @@ void evergreen_pcie_gen2_enable(struct radeon_device *rdev)
 	if (ASIC_IS_X2(rdev))
 		return;
 
+	ret = drm_pcie_get_speed_cap_mask(rdev->ddev, &mask);
+	if (ret != 0)
+		return;
+
+	if (!(mask & DRM_PCIE_SPEED_50))
+		return;
+
+	DRM_INFO("enabling PCIE gen 2 link speeds, disable with radeon.pcie_gen2=0\n");
+
 	speed_cntl = RREG32_PCIE_P(PCIE_LC_SPEED_CNTL);
 	if ((speed_cntl & LC_OTHER_SIDE_EVER_SENT_GEN2) ||
 	    (speed_cntl & LC_OTHER_SIDE_SUPPORTS_GEN2)) {

drivers/gpu/drm/radeon/r600.c

@@ -3681,6 +3681,8 @@ static void r600_pcie_gen2_enable(struct radeon_device *rdev)
 {
 	u32 link_width_cntl, lanes, speed_cntl, training_cntl, tmp;
 	u16 link_cntl2;
+	u32 mask;
+	int ret;
 
 	if (radeon_pcie_gen2 == 0)
 		return;
@@ -3699,6 +3701,15 @@ static void r600_pcie_gen2_enable(struct radeon_device *rdev)
 	if (rdev->family <= CHIP_R600)
 		return;
 
+	ret = drm_pcie_get_speed_cap_mask(rdev->ddev, &mask);
+	if (ret != 0)
+		return;
+
+	if (!(mask & DRM_PCIE_SPEED_50))
+		return;
+
+	DRM_INFO("enabling PCIE gen 2 link speeds, disable with radeon.pcie_gen2=0\n");
+
 	/* 55 nm r6xx asics */
 	if ((rdev->family == CHIP_RV670) ||
 	    (rdev->family == CHIP_RV620) ||

drivers/gpu/drm/radeon/radeon_drv.c

@@ -133,7 +133,7 @@ int radeon_tv = 1;
 int radeon_audio = 0;
 int radeon_disp_priority = 0;
 int radeon_hw_i2c = 0;
-int radeon_pcie_gen2 = 0;
+int radeon_pcie_gen2 = -1;
 int radeon_msi = -1;
 int radeon_lockup_timeout = 10000;
 
@@ -179,7 +179,7 @@ module_param_named(disp_priority, radeon_disp_priority, int, 0444);
 MODULE_PARM_DESC(hw_i2c, "hw i2c engine enable (0 = disable)");
 module_param_named(hw_i2c, radeon_hw_i2c, int, 0444);
 
-MODULE_PARM_DESC(pcie_gen2, "PCIE Gen2 mode (1 = enable)");
+MODULE_PARM_DESC(pcie_gen2, "PCIE Gen2 mode (-1 = auto, 0 = disable, 1 = enable)");
 module_param_named(pcie_gen2, radeon_pcie_gen2, int, 0444);
 
 MODULE_PARM_DESC(msi, "MSI support (1 = enable, 0 = disable, -1 = auto)");

drivers/gpu/drm/radeon/rv770.c

@@ -1112,6 +1112,8 @@ static void rv770_pcie_gen2_enable(struct radeon_device *rdev)
 {
 	u32 link_width_cntl, lanes, speed_cntl, tmp;
 	u16 link_cntl2;
+	u32 mask;
+	int ret;
 
 	if (radeon_pcie_gen2 == 0)
 		return;
@@ -1126,6 +1128,15 @@ static void rv770_pcie_gen2_enable(struct radeon_device *rdev)
 	if (ASIC_IS_X2(rdev))
 		return;
 
+	ret = drm_pcie_get_speed_cap_mask(rdev->ddev, &mask);
+	if (ret != 0)
+		return;
+
+	if (!(mask & DRM_PCIE_SPEED_50))
+		return;
+
+	DRM_INFO("enabling PCIE gen 2 link speeds, disable with radeon.pcie_gen2=0\n");
+
 	/* advertise upconfig capability */
 	link_width_cntl = RREG32_PCIE_P(PCIE_LC_LINK_WIDTH_CNTL);
 	link_width_cntl &= ~LC_UPCONFIGURE_DIS;