[PATCH v6 3/3] PCI: rockchip: drive at 2.5 GT/s, error other speeds

[Geraldo Nascimento]

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")
Link: https://lore.kernel.org/all/ffd05070-9879-4468-94e3-b88968b4c21b@rock-chips.com/
Cc: stable at vger.kernel.org
Reported-by: Dragan Simic <dsimic at manjaro.org>
Reported-by: Shawn Lin <shawn.lin at rock-chips.com>
Signed-off-by: Geraldo Nascimento <geraldogabriel at gmail.com>
---
 drivers/pci/controller/pcie-rockchip.c | 16 +++++++++-------
 drivers/pci/controller/pcie-rockchip.h |  3 ---
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/controller/pcie-rockchip.c b/drivers/pci/controller/pcie-rockchip.c
index 0f88da3788054..5a2876d7c8547 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");
+	}
 
 	for (i = 0; i < ROCKCHIP_NUM_PM_RSTS; i++)
 		rockchip->pm_rsts[i].id = rockchip_pci_pm_rsts[i];
@@ -147,12 +149,12 @@ int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
 		goto err_exit_phy;
 	}
 
+	/* 5.0 GT/s may cause catastrophic failure for this core */
 	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);
+		dev_warn(dev, "5.0 GT/s may cause data loss or worse\n");
+
+	rockchip_pcie_write(rockchip, PCIE_CLIENT_GEN_SEL_1,
+			    PCIE_CLIENT_CONFIG);
 
 	regs = 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 3e82a69b9c006..b5da15601b585 100644
--- a/drivers/pci/controller/pcie-rockchip.h
+++ b/drivers/pci/controller/pcie-rockchip.h
@@ -42,7 +42,6 @@
 #define   PCIE_CLIENT_MODE_RC			HWORD_SET_BIT(0x0040)
 #define   PCIE_CLIENT_MODE_EP			HWORD_CLR_BIT(0x0040)
 #define   PCIE_CLIENT_GEN_SEL_1			HWORD_CLR_BIT(0x0080)
-#define   PCIE_CLIENT_GEN_SEL_2			HWORD_SET_BIT(0x0080)
 #define PCIE_CLIENT_LEGACY_INT_CTRL	(PCIE_CLIENT_BASE + 0x0c)
 #define   PCIE_CLIENT_INT_IN_ASSERT		HWORD_SET_BIT(0x0002)
 #define   PCIE_CLIENT_INT_IN_DEASSERT		HWORD_CLR_BIT(0x0002)
@@ -197,8 +196,6 @@
 	(((x) & PCIE_CORE_PL_CONF_LS_MASK) == PCIE_CORE_PL_CONF_LS_READY)
 #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
-- 
2.54.0