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

[Dragan Simic]

Hello Geraldo,

On Saturday, November 15, 2025 10:10 CET, Geraldo Nascimento <geraldogabriel at gmail.com> wrote:
> 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 at rock-chips.com>
> Signed-off-by: Geraldo Nascimento <geraldogabriel at 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;

Looking good to me, thanks for this patch!  There's no need
to emit warnings here, because they'd be emitted already in
the rockchip_pcie_parse_dt() function.

Please feel free to include

Reviewed-by: Dragan Simic <dsimic at manjaro.org>