[PATCH v4] PCI: rcar: Fix missing MACCTLR register setting in rcar_pcie_hw_init()

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>]

According to the R-Car Gen2/3 manual, the bit 0 of MACCTLR register
should be written to 0 before enabling PCIETCTLR.CFINIT because
the bit 0 is set to 1 on reset. To avoid unexpected behaviors from
this incorrect setting, this patch fixes it.

Fixes: c25da4778803 ("PCI: rcar: Add Renesas R-Car PCIe driver")
Fixes: be20bbcb0a8c ("PCI: rcar: Add the initialization of PCIe link in resume_noirq()")
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 Changes from v3:
 - Add the setting in rcar_pcie_resume_noirq().
 - Add Fixes tag for rcar_pcie_resume_noirq().
 - Change the version of the stable ML from v3.16 to v5.2.
 https://patchwork.kernel.org/patch/11181005/

 Changes from v2:
 - Change the subject.
 - Fix commit log again.
 - Add the register setting into the initialization, instead of speedup.
 - Change commit hash/target version on Fixes and Cc stable tags.
 - Add Geert-san's Reviewed-by.
 https://patchwork.kernel.org/patch/11180429/

 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, 4 insertions(+)

diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
index f6a669a..302c9ea 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
@@ -615,6 +616,8 @@ static int rcar_pcie_hw_init(struct rcar_pcie *pcie)
 	if (IS_ENABLED(CONFIG_PCI_MSI))
 		rcar_pci_write_reg(pcie, 0x801f0000, PCIEMSITXR);
 
+	rcar_rmw32(pcie, MACCTLR, MACCTLR_RESERVED, 0);
+
 	/* Finish initialization - establish a PCI Express link */
 	rcar_pci_write_reg(pcie, CFINIT, PCIETCTLR);
 
@@ -1237,6 +1240,7 @@ static int rcar_pcie_resume_noirq(struct device *dev)
 		return 0;
 
 	/* Re-establish the PCIe link */
+	rcar_rmw32(pcie, MACCTLR, MACCTLR_RESERVED, 0);
 	rcar_pci_write_reg(pcie, CFINIT, PCIETCTLR);
 	return rcar_pcie_wait_for_dl(pcie);
 }
-- 
2.7.4