Don't assume that only the driver would be accessing LNKCTL2. In the
case of upstream (parent), the driver does not even own the device it's
changing the registers for.

Use RMW capability accessors which do proper locking to avoid losing
concurrent updates to the register value. This change is also useful as
a cleanup.

Suggested-by: Lukas Wunner <lu...@wunner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvi...@linux.intel.com>
---
 drivers/gpu/drm/radeon/cik.c | 40 ++++++++++++++----------------------
 drivers/gpu/drm/radeon/si.c  | 40 ++++++++++++++----------------------
 2 files changed, 30 insertions(+), 50 deletions(-)

diff --git a/drivers/gpu/drm/radeon/cik.c b/drivers/gpu/drm/radeon/cik.c
index 10be30366c2b..b5e96a8fc2c1 100644
--- a/drivers/gpu/drm/radeon/cik.c
+++ b/drivers/gpu/drm/radeon/cik.c
@@ -9592,28 +9592,18 @@ static void cik_pcie_gen3_enable(struct radeon_device 
*rdev)
                                                                   
PCI_EXP_LNKCTL_HAWD);
 
                                /* linkctl2 */
-                               pcie_capability_read_word(root, PCI_EXP_LNKCTL2,
-                                                         &tmp16);
-                               tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN);
-                               tmp16 |= (bridge_cfg2 &
-                                         (PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN));
-                               pcie_capability_write_word(root,
-                                                          PCI_EXP_LNKCTL2,
-                                                          tmp16);
-
-                               pcie_capability_read_word(rdev->pdev,
-                                                         PCI_EXP_LNKCTL2,
-                                                         &tmp16);
-                               tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN);
-                               tmp16 |= (gpu_cfg2 &
-                                         (PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN));
-                               pcie_capability_write_word(rdev->pdev,
-                                                          PCI_EXP_LNKCTL2,
-                                                          tmp16);
+                               pcie_capability_clear_and_set_word(root, 
PCI_EXP_LNKCTL2,
+                                                                  
PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                  
PCI_EXP_LNKCTL2_TX_MARGIN,
+                                                                  bridge_cfg2 |
+                                                                  
(PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                   
PCI_EXP_LNKCTL2_TX_MARGIN));
+                               pcie_capability_clear_and_set_word(rdev->pdev, 
PCI_EXP_LNKCTL2,
+                                                                  
PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                  
PCI_EXP_LNKCTL2_TX_MARGIN,
+                                                                  gpu_cfg2 |
+                                                                  
(PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                   
PCI_EXP_LNKCTL2_TX_MARGIN));
 
                                tmp = RREG32_PCIE_PORT(PCIE_LC_CNTL4);
                                tmp &= ~LC_SET_QUIESCE;
@@ -9627,15 +9617,15 @@ static void cik_pcie_gen3_enable(struct radeon_device 
*rdev)
        speed_cntl &= ~LC_FORCE_DIS_SW_SPEED_CHANGE;
        WREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL, speed_cntl);
 
-       pcie_capability_read_word(rdev->pdev, PCI_EXP_LNKCTL2, &tmp16);
-       tmp16 &= ~PCI_EXP_LNKCTL2_TLS;
+       tmp16 = 0;
        if (speed_cap == PCIE_SPEED_8_0GT)
                tmp16 |= PCI_EXP_LNKCTL2_TLS_8_0GT; /* gen3 */
        else if (speed_cap == PCIE_SPEED_5_0GT)
                tmp16 |= PCI_EXP_LNKCTL2_TLS_5_0GT; /* gen2 */
        else
                tmp16 |= PCI_EXP_LNKCTL2_TLS_2_5GT; /* gen1 */
-       pcie_capability_write_word(rdev->pdev, PCI_EXP_LNKCTL2, tmp16);
+       pcie_capability_clear_and_set_word(rdev->pdev, PCI_EXP_LNKCTL2,
+                                          PCI_EXP_LNKCTL2_TLS, tmp16);
 
        speed_cntl = RREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL);
        speed_cntl |= LC_INITIATE_LINK_SPEED_CHANGE;
diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index a91012447b56..32871ca09a0f 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -7189,28 +7189,18 @@ static void si_pcie_gen3_enable(struct radeon_device 
*rdev)
                                                                   
PCI_EXP_LNKCTL_HAWD);
 
                                /* linkctl2 */
-                               pcie_capability_read_word(root, PCI_EXP_LNKCTL2,
-                                                         &tmp16);
-                               tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN);
-                               tmp16 |= (bridge_cfg2 &
-                                         (PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN));
-                               pcie_capability_write_word(root,
-                                                          PCI_EXP_LNKCTL2,
-                                                          tmp16);
-
-                               pcie_capability_read_word(rdev->pdev,
-                                                         PCI_EXP_LNKCTL2,
-                                                         &tmp16);
-                               tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN);
-                               tmp16 |= (gpu_cfg2 &
-                                         (PCI_EXP_LNKCTL2_ENTER_COMP |
-                                          PCI_EXP_LNKCTL2_TX_MARGIN));
-                               pcie_capability_write_word(rdev->pdev,
-                                                          PCI_EXP_LNKCTL2,
-                                                          tmp16);
+                               pcie_capability_clear_and_set_word(root, 
PCI_EXP_LNKCTL2,
+                                                                  
PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                  
PCI_EXP_LNKCTL2_TX_MARGIN,
+                                                                  bridge_cfg2 &
+                                                                  
(PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                   
PCI_EXP_LNKCTL2_TX_MARGIN));
+                               pcie_capability_clear_and_set_word(rdev->pdev, 
PCI_EXP_LNKCTL2,
+                                                                  
PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                  
PCI_EXP_LNKCTL2_TX_MARGIN,
+                                                                  gpu_cfg2 &
+                                                                  
(PCI_EXP_LNKCTL2_ENTER_COMP |
+                                                                   
PCI_EXP_LNKCTL2_TX_MARGIN));
 
                                tmp = RREG32_PCIE_PORT(PCIE_LC_CNTL4);
                                tmp &= ~LC_SET_QUIESCE;
@@ -7224,15 +7214,15 @@ static void si_pcie_gen3_enable(struct radeon_device 
*rdev)
        speed_cntl &= ~LC_FORCE_DIS_SW_SPEED_CHANGE;
        WREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL, speed_cntl);
 
-       pcie_capability_read_word(rdev->pdev, PCI_EXP_LNKCTL2, &tmp16);
-       tmp16 &= ~PCI_EXP_LNKCTL2_TLS;
+       tmp16 = 0;
        if (speed_cap == PCIE_SPEED_8_0GT)
                tmp16 |= PCI_EXP_LNKCTL2_TLS_8_0GT; /* gen3 */
        else if (speed_cap == PCIE_SPEED_5_0GT)
                tmp16 |= PCI_EXP_LNKCTL2_TLS_5_0GT; /* gen2 */
        else
                tmp16 |= PCI_EXP_LNKCTL2_TLS_2_5GT; /* gen1 */
-       pcie_capability_write_word(rdev->pdev, PCI_EXP_LNKCTL2, tmp16);
+       pcie_capability_clear_and_set_word(rdev->pdev, PCI_EXP_LNKCTL2,
+                                          PCI_EXP_LNKCTL2_TLS, tmp16);
 
        speed_cntl = RREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL);
        speed_cntl |= LC_INITIATE_LINK_SPEED_CHANGE;
-- 
2.30.2

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