[PATCH 6.6.y] PCI: rockchip: Drive at 2.5 GT/s, error other speeds

[Sasha Levin <sashal@kernel.org>]

From: Geraldo Nascimento <geraldogabriel@gmail.com>

[ Upstream commit 84d08ff902f1ec01177fef1a21a38934927f5aee ]

Configure the core to be driven at 2.5 GT/s Link Speed and ignore any other
speed with a warning. Also drop the 5.0 GT/s Link Speed defines from
Rockchip PCIe header.

The reason is that Shawn Lin from Rockchip has reiterated that there may be
danger of "catastrophic failure" in using their PCIe with 5.0 GT/s speeds.

While Rockchip has done so informally without issuing a proper errata, and
the particulars are thus unknown, this may cause data loss or worse.

This change is corroborated by RK3399 official datasheet [1], which states
maximum link speed for this platform is 2.5 GT/s.

[1] https://opensource.rock-chips.com/images/d/d7/Rockchip_RK3399_Datasheet_V2.1-20200323.pdf

Fixes: 956cd99b35a8 ("PCI: rockchip: Separate common code from RC driver")
Reported-by: Dragan Simic <dsimic@manjaro.org>
Reported-by: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://lore.kernel.org/all/ffd05070-9879-4468-94e3-b88968b4c21b@rock-chips.com/
Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/7421df7a7b7778ee99363cccfdfabbfa8aa6ab5e.1781622998.git.geraldogabriel@gmail.com
[ sashal: adjusted patch context for the older Rockchip PCIe driver implementation ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/pci/controller/pcie-rockchip.c | 14 ++++++--------
 drivers/pci/controller/pcie-rockchip.h |  3 ---
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/controller/pcie-rockchip.c b/drivers/pci/controller/pcie-rockchip.c
index c07d7129f1c7c..6a970dc766d4d 100644
--- a/drivers/pci/controller/pcie-rockchip.c
+++ b/drivers/pci/controller/pcie-rockchip.c
@@ -66,8 +66,10 @@ int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
 	}
 
 	rockchip->link_gen = of_pci_get_max_link_speed(node);
-	if (rockchip->link_gen < 0 || rockchip->link_gen > 2)
-		rockchip->link_gen = 2;
+	if (rockchip->link_gen < 0 || rockchip->link_gen >= 2) {
+		rockchip->link_gen = 1;
+		dev_warn(dev, "invalid max-link-speed, limited to 2.5 GT/s\n");
+	}
 
 	rockchip->core_rst = devm_reset_control_get_exclusive(dev, "core");
 	if (IS_ERR(rockchip->core_rst)) {
@@ -237,12 +239,8 @@ int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
 		goto err_exit_phy;
 	}
 
-	if (rockchip->link_gen == 2)
-		rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_2,
-				    PCIE_CLIENT_CONFIG);
-	else
-		rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_1,
-				    PCIE_CLIENT_CONFIG);
+	rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_1,
+			    PCIE_CLIENT_CONFIG);
 
 	regs = PCIE_CLIENT_LINK_TRAIN_ENABLE | PCIE_CLIENT_ARI_ENABLE |
 	       PCIE_CLIENT_CONF_LANE_NUM(rockchip->lanes);
diff --git a/drivers/pci/controller/pcie-rockchip.h b/drivers/pci/controller/pcie-rockchip.h
index 049ad984a4164..4702caac56114 100644
--- a/drivers/pci/controller/pcie-rockchip.h
+++ b/drivers/pci/controller/pcie-rockchip.h
@@ -37,7 +37,6 @@
 #define   PCIE_CLIENT_MODE_RC		  HIWORD_UPDATE_BIT(0x0040)
 #define   PCIE_CLIENT_MODE_EP            HIWORD_UPDATE(0x0040, 0)
 #define   PCIE_CLIENT_GEN_SEL_1		  HIWORD_UPDATE(0x0080, 0)
-#define   PCIE_CLIENT_GEN_SEL_2		  HIWORD_UPDATE_BIT(0x0080)
 #define PCIE_CLIENT_LEGACY_INT_CTRL	(PCIE_CLIENT_BASE + 0x0c)
 #define   PCIE_CLIENT_INT_IN_ASSERT		HIWORD_UPDATE_BIT(0x0002)
 #define   PCIE_CLIENT_INT_IN_DEASSERT		HIWORD_UPDATE(0x0002, 0)
@@ -184,8 +183,6 @@
 	(((x) & PCIE_CLIENT_DEBUG_LTSSM_MASK) == PCIE_CLIENT_DEBUG_LTSSM_L2)
 #define PCIE_LINK_UP(x) \
 	(((x) & PCIE_CLIENT_LINK_STATUS_MASK) == PCIE_CLIENT_LINK_STATUS_UP)
-#define PCIE_LINK_IS_GEN2(x) \
-	(((x) & PCIE_CORE_PL_CONF_SPEED_MASK) == PCIE_CORE_PL_CONF_SPEED_5G)
 
 #define RC_REGION_0_ADDR_TRANS_H		0x00000000
 #define RC_REGION_0_ADDR_TRANS_L		0x00000000
-- 
2.53.0