[U-Boot] [PATCH] PCI: layerscape: Make the pcie link up status judgement more specific

[York Sun]

On 08/15/2017 03:03 AM, Bao Xiaowei wrote:
> For some special reset times for longer pcie devices, in this case, the
> pcie device may on polling compliance state, the RC considers the pcie
> device is link up, but the pcie device is not link up, only the L0 state
> is link up state. So add the link up status judgement mechanisms.
> 

Xiaowei,

Let me try to rephrase your commit message. Correct me if I get it 
wrong. I think you mean

Determine PCIe link status by checking L0 state. If L0 state is detected 
within 100ms, link status is reported as up.

> Signed-off-by: Bao Xiaowei <xiaowei.bao at nxp.com>
> ---

For future patches, please add change log here and revision number in 
the subject.

>   drivers/pci/pcie_layerscape.c | 25 +++++++++++++++++++++----
>   drivers/pci/pcie_layerscape.h |  3 +++
>   2 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/pcie_layerscape.c b/drivers/pci/pcie_layerscape.c
> index 78cde21..4db95c5 100644
> --- a/drivers/pci/pcie_layerscape.c
> +++ b/drivers/pci/pcie_layerscape.c
> @@ -69,13 +69,30 @@ static int ls_pcie_ltssm(struct ls_pcie *pcie)
>   
>   static int ls_pcie_link_up(struct ls_pcie *pcie)
>   {
> -	int ltssm;
> +	int ltssm, i;
>   
>   	ltssm = ls_pcie_ltssm(pcie);
> -	if (ltssm < LTSSM_PCIE_L0)
> -		return 0;
>   
> -	return 1;
> +	/*
> +	 * For some special reset times for longer pcie devices,
> +	 * the pcie device may on polling compliance state,
> +	 * on this state, if the device can restored to the L0 state
> +	 * within 100ms considers the pcie device is link up
> +	 */

> +	if (ltssm == LTSSM_PCIE_DETECT_QUIET ||
> +	    ltssm == LTSSM_PCIE_DETECT_ACTIVE) {

Please explain the above two lines with comment.

> +		return 0;
> +	} else if (ltssm == LTSSM_PCIE_L0) {
> +		return 1;
> +	} else {

How about this comment?
	/*
	 * For some devices requiring longer reset time, check if L0
	 * state can be reached within 100ms.
	 */

> +		for (i = 0; i < 100; i++) {
> +			udelay(1000);
> +			ltssm = ls_pcie_ltssm(pcie);
> +			if (ltssm == LTSSM_PCIE_L0)
> +				return 1;
> +		}
> +		return 0;
> +	}
>   }
>   
>   static void ls_pcie_cfg0_set_busdev(struct ls_pcie *pcie, u32 busdev)
> diff --git a/drivers/pci/pcie_layerscape.h b/drivers/pci/pcie_layerscape.h
> index 782e3ab..4313e85 100644
> --- a/drivers/pci/pcie_layerscape.h
> +++ b/drivers/pci/pcie_layerscape.h
> @@ -70,6 +70,9 @@
>   
>   #define LTSSM_STATE_MASK	0x3f
>   #define LTSSM_PCIE_L0		0x11 /* L0 state */
> +#define LTSSM_PCIE_DETECT_QUIET		0x00 /* L0 state */
> +#define LTSSM_PCIE_DETECT_ACTIVE	0x01 /* L0 state */
> +#define LTSSM_PCIE_L0		0x11 /* L0 state */
>   
>   #define PCIE_DBI_SIZE		0x100000 /* 1M */
>   
> 

York