[PATCH v4 3/4] PCI: rockchip-host: do not attempt 5.0 GT/s retraining

[Geraldo Nascimento]

Drop the 5.0 GT/s Link Speed retraining from Rockchip PCIe Root
Complex Mode Operation, so called host driver.

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

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-host.c | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index ee1822ca01db..1374a2c92b56 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -328,26 +328,6 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
 		goto err_power_off_phy;
 	}
 
-	if (rockchip->link_gen == 2) {
-		/*
-		 * Enable retrain for gen2. This should be configured only after
-		 * gen1 finished.
-		 */
-		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL2);
-		status &= ~PCI_EXP_LNKCTL2_TLS;
-		status |= PCI_EXP_LNKCTL2_TLS_5_0GT;
-		rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL2);
-		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL);
-		status |= PCI_EXP_LNKCTL_RL;
-		rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL);
-
-		err = readl_poll_timeout(rockchip->apb_base + PCIE_CORE_CTRL,
-					 status, PCIE_LINK_IS_GEN2(status), 20,
-					 500 * USEC_PER_MSEC);
-		if (err)
-			dev_dbg(dev, "PCIe link training gen2 timeout, fall back to gen1!\n");
-	}
-
 	/* Check the final link width from negotiated lane counter from MGMT */
 	status = rockchip_pcie_read(rockchip, PCIE_CORE_CTRL);
 	status = 0x1 << ((status & PCIE_CORE_PL_CONF_LANE_MASK) >>
-- 
2.52.0