[U-Boot] [PATCH] mvebu: a38x: Force receiver detected on PCIe lanes

[Stefan Roese]

(Added Mario and Chris)

On 27.05.2018 17:34, Baruch Siach wrote:
> From: Rabeeh Khoury <rabeeh at solid-run.com>
> 
> Some QCA988x based modules presence is not detected by the SERDES lanes,
> so force this detection which will trigger the LTSSM state machine to
> negotiate link.
> 
> An example of such a card is WLE900VX.
> 
> Signed-off-by: Rabeeh Khoury <rabeeh at solid-run.com>
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
>   arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c | 2 ++
>   arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h         | 1 +
>   2 files changed, 3 insertions(+)
> 
> diff --git a/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c b/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c
> index 13553cf96008..33e70569bc48 100644
> --- a/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c
> +++ b/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c
> @@ -597,6 +597,8 @@ struct op_params pex_electrical_config_serdes_rev2_params[] = {
>   	{LANE_CFG4_REG, 0x800, 0x8, {0x8}, 0, 0},
>   	/* tximpcal_th and rximpcal_th */
>   	{VTHIMPCAL_CTRL_REG, 0x800, 0xff00, {0x3000}, 0, 0},
> +	/* Force receiver detected */
> +	{LANE_CFG0_REG, 0x800, 0x8000, {0x8000}, 0, 0},
>   };
>   
>   /* PEX - configuration seq for REF_CLOCK_25MHz */
> diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> index 953445b7d7ae..50b235826659 100644
> --- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> +++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> @@ -71,6 +71,7 @@
>   #define RX_REG3				0xa0188
>   #define PCIE_REG1			0xa0288
>   #define PCIE_REG3			0xa0290
> +#define LANE_CFG0_REG			0xa0600
>   #define LANE_CFG1_REG			0xa0604
>   #define LANE_CFG4_REG			0xa0620
>   #define LANE_CFG5_REG			0xa0624
> 

I understand that this might fix an issue on a specific board (ClearFog
in this case, correct?). But are you sure that its safe to force this
link detection for all A38x boards?

Thanks,
Stefan