diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index d8d71a399f527ac1c729e25221fc95f503251091..dc0a5b56c81a6ee8dbc5d670a38c6330b683521a 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -41,6 +41,31 @@ static void evergreen_gpu_init(struct radeon_device *rdev);
 void evergreen_fini(struct radeon_device *rdev);
 static void evergreen_pcie_gen2_enable(struct radeon_device *rdev);
 
+void evergreen_fix_pci_max_read_req_size(struct radeon_device *rdev)
+{
+	u16 ctl, v;
+	int cap, err;
+
+	cap = pci_pcie_cap(rdev->pdev);
+	if (!cap)
+		return;
+
+	err = pci_read_config_word(rdev->pdev, cap + PCI_EXP_DEVCTL, &ctl);
+	if (err)
+		return;
+
+	v = (ctl & PCI_EXP_DEVCTL_READRQ) >> 12;
+
+	/* if bios or OS sets MAX_READ_REQUEST_SIZE to an invalid value, fix it
+	 * to avoid hangs or perfomance issues
+	 */
+	if ((v == 0) || (v == 6) || (v == 7)) {
+		ctl &= ~PCI_EXP_DEVCTL_READRQ;
+		ctl |= (2 << 12);
+		pci_write_config_word(rdev->pdev, cap + PCI_EXP_DEVCTL, ctl);
+	}
+}
+
 void evergreen_pre_page_flip(struct radeon_device *rdev, int crtc)
 {
 	/* enable the pflip int */
@@ -1863,6 +1888,8 @@ static void evergreen_gpu_init(struct radeon_device *rdev)
 
 	WREG32(GRBM_CNTL, GRBM_READ_TIMEOUT(0xff));
 
+	evergreen_fix_pci_max_read_req_size(rdev);
+
 	cc_gc_shader_pipe_config = RREG32(CC_GC_SHADER_PIPE_CONFIG) & ~2;
 
 	cc_gc_shader_pipe_config |=
diff --git a/drivers/gpu/drm/radeon/ni.c b/drivers/gpu/drm/radeon/ni.c
index a2e00fa9c6185989f02e9847d81dc156335adda8..cbf57d75d925be3c65f88738902091dc1cc8e7d0 100644
--- a/drivers/gpu/drm/radeon/ni.c
+++ b/drivers/gpu/drm/radeon/ni.c
@@ -39,6 +39,7 @@ extern int evergreen_mc_wait_for_idle(struct radeon_device *rdev);
 extern void evergreen_mc_program(struct radeon_device *rdev);
 extern void evergreen_irq_suspend(struct radeon_device *rdev);
 extern int evergreen_mc_init(struct radeon_device *rdev);
+extern void evergreen_fix_pci_max_read_req_size(struct radeon_device *rdev);
 
 #define EVERGREEN_PFP_UCODE_SIZE 1120
 #define EVERGREEN_PM4_UCODE_SIZE 1376
@@ -669,6 +670,8 @@ static void cayman_gpu_init(struct radeon_device *rdev)
 
 	WREG32(GRBM_CNTL, GRBM_READ_TIMEOUT(0xff));
 
+	evergreen_fix_pci_max_read_req_size(rdev);
+
 	mc_shared_chmap = RREG32(MC_SHARED_CHMAP);
 	mc_arb_ramcfg = RREG32(MC_ARB_RAMCFG);
 
diff --git a/drivers/gpu/drm/radeon/radeon_clocks.c b/drivers/gpu/drm/radeon/radeon_clocks.c
index dcd0863e31ae8c24b1a8870aa777bbe2c550ce2b..b6e18c8db9f53511e2141a0f20aa2ec2880b263d 100644
--- a/drivers/gpu/drm/radeon/radeon_clocks.c
+++ b/drivers/gpu/drm/radeon/radeon_clocks.c
@@ -219,6 +219,9 @@ void radeon_get_clock_info(struct drm_device *dev)
 		} else {
 			DRM_INFO("Using generic clock info\n");
 
+			/* may need to be per card */
+			rdev->clock.max_pixel_clock = 35000;
+
 			if (rdev->flags & RADEON_IS_IGP) {
 				p1pll->reference_freq = 1432;
 				p2pll->reference_freq = 1432;