[PATCH 2/3] PCI: rockchip-host: comment danger of 5.0 GT/s speed

[Geraldo Nascimento <geraldogabriel@gmail.com>]

According to Rockchip sources, there is grave danger in enabling 5.0
GT/s speed for this core. Add a comment documenting that danger and
discouraging end-users from forcing higher speed through DT changes.

Link: https://lore.kernel.org/all/ffd05070-9879-4468-94e3-b88968b4c21b@rock-chips.com/
Reported-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>
---
 drivers/pci/controller/pcie-rockchip-host.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index ee1822ca01db..7e6ff76466b7 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -332,6 +332,11 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
 		/*
 		 * Enable retrain for gen2. This should be configured only after
 		 * gen1 finished.
+		 *
+		 * According to Rockchip this path is dangerous and may lead to
+		 * catastrophic failure. Even if the odds are small, users are
+		 * still discouraged to engage the corresponding DT option.
+		 *
 		 */
 		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL2);
 		status &= ~PCI_EXP_LNKCTL2_TLS;
-- 
2.49.0