[PATCH v2 0/4] PCI: rockchip: 5.0 GT/s speed may be dangerous

Geraldo Nascimento
2025-11-17T21:47:13Z

Dragan Simic already had warned me of potential issues with 5.0 GT/s
speed operation in Rockchip PCIe. However, in recent interactions
with Shawn Lin from Rockchip it came to my attention there's grave
danger in the unknown errata regarding 5.0 GT/s operational speed
of their PCIe core. Even if the odds are low, to contain any damage,
let's cover the remaining corner-cases where the default would lead
to 5.0 GT/s operation as well as add a comment to Root Complex driver
core, documenting this danger. Furthermore, remove redundant
declaration of max-link-speed from rk3399-nanopi-r4s.dtsi

Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>

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Changes in v2:
- hard limit to 2.5 GT/s, not just warn
- add Reported-by: and Reviewed-by: Dragan Simic
- remove redundant declaration of max-link-speed from helios64 dts
- fix Link: of helios64 patch
- simplify RC mode comment
- Link to v1: https://lore.kernel.org/all/aRhR79u5BPtRRFw3@geday/

Geraldo Nascimento (4):
PCI: rockchip: limit RK3399 to 2.5 GT/s to prevent damage
PCI: rockchip-host: comment danger of 5.0 GT/s speed
arm64: dts: rockchip: remove dangerous max-link-speed from helios64
arm64: dts: rockchip: remove redundant max-link-speed from nanopi-r4s

arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts | 1 -
arch/arm64/boot/dts/rockchip/rk3399-nanopi-r4s.dtsi | 1 -
drivers/pci/controller/pcie-rockchip-host.c | 3 +++
drivers/pci/controller/pcie-rockchip.c | 10 ++++++++--
4 files changed, 11 insertions(+), 4 deletions(-)

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2.49.0