[U-Boot] [PATCH] drivers: pci: imx: fix enumeration logic error

[Stefano Babic]

On 04/01/2018 14:54, Koen Vandeputte wrote:
> By default, the subordinate is set equally to the secondary bus (1) when
> the RC boots, and does not alter afterwards.
> 
> This means that theoretically, the highest bus reachable downstream is
> bus 1.
> 
> Force the PCIe RC subordinate to 0xff, otherwise no downstream
> devices will be detected behind bus 1 if the booting OS does not allow
> enumerating a higher busnr than the subordinate value of the primary
> bus.
> 
> Signed-off-by: Koen Vandeputte <koen.vandeputte at ncentric.com>
> ---
>  drivers/pci/pcie_imx.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/pci/pcie_imx.c b/drivers/pci/pcie_imx.c
> index 2900c8d..9277af9 100644
> --- a/drivers/pci/pcie_imx.c
> +++ b/drivers/pci/pcie_imx.c
> @@ -612,6 +612,17 @@ static int imx_pcie_link_up(void)
>  	imx_pcie_regions_setup();
>  
>  	/*
> +	 * By default, the subordinate is set equally to the secondary
> +	 * bus (0x01) when the RC boots.
> +	 * This means that theoretically, only bus 1 is reachable from the RC.
> +	 * Force the PCIe RC subordinate to 0xff, otherwise no downstream
> +	 * devices will be detected if the enumeration is applied strictly.
> +	 */
> +	tmp = readl(MX6_DBI_ADDR + 0x18);
> +	tmp |= (0xff << 16);
> +	writel(tmp, MX6_DBI_ADDR + 0x18);
> +
> +	/*
>  	 * FIXME: Force the PCIe RC to Gen1 operation
>  	 * The RC must be forced into Gen1 mode before bringing the link
>  	 * up, otherwise no downstream devices are detected. After the
> 

Applied to u-boot-imx, thanks !

Best regards,
Stefano Babic

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