According to the R-Car Gen2/3 manual, the bit 0 of MACCTLR register
should be written to 0 because the register is set to 1 on reset.
To avoid unexpected behaviors from this incorrect setting, this
patch fixes it.
Fixes: b3327f7fae66 ("PCI: rcar: Try increasing PCIe link speed to 5 GT/s at boot")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.9+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
---
Changes from v1:
- Fix commit log.
- Add Sergei-san's Reviewed-by.
https://patchwork.kernel.org/patch/11179279/
drivers/pci/controller/pcie-rcar.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
index f6a669a..9eb9b25 100644
--- a/drivers/pci/controller/pcie-rcar.c
+++ b/drivers/pci/controller/pcie-rcar.c
@@ -93,6 +93,7 @@
#define LINK_SPEED_2_5GTS (1 << 16)
#define LINK_SPEED_5_0GTS (2 << 16)
#define MACCTLR 0x011058
+#define MACCTLR_RESERVED BIT(0)
#define SPEED_CHANGE BIT(24)
#define SCRAMBLE_DISABLE BIT(27)
#define PMSR 0x01105c
@@ -427,7 +428,8 @@ static void rcar_pcie_force_speedup(struct rcar_pcie *pcie)
rcar_pci_write_reg(pcie, macsr, MACSR);
/* Start link speed change */
- rcar_rmw32(pcie, MACCTLR, SPEED_CHANGE, SPEED_CHANGE);
+ rcar_rmw32(pcie, MACCTLR, SPEED_CHANGE | MACCTLR_RESERVED,
+ SPEED_CHANGE);
while (timeout--) {
macsr = rcar_pci_read_reg(pcie, MACSR);
--
2.7.4
