Re: [PATCH] PCI: altera: Poll for link training status after retraining the link

[Bjorn Helgaas]

On Mon, Aug 15, 2016 at 02:06:02PM +0800, Ley Foon Tan wrote:
> Poll for link training status is cleared before poll for link up status.
> This can help to get the reliable link up status, especially when PCIe
> is in Gen 3 speed.
> 
> Signed-off-by: Ley Foon Tan <lf...@altera.com>

Applied to pci/host-altera for v4.9, thanks!

> ---
>  drivers/pci/host/pcie-altera.c | 45 
> ++++++++++++++++++++++++++++++++++--------
>  1 file changed, 37 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/host/pcie-altera.c b/drivers/pci/host/pcie-altera.c
> index 2b78376..58eef99 100644
> --- a/drivers/pci/host/pcie-altera.c
> +++ b/drivers/pci/host/pcie-altera.c
> @@ -61,7 +61,8 @@
>  #define TLP_LOOP                     500
>  #define RP_DEVFN                     0
>  
> -#define LINK_UP_TIMEOUT                      5000
> +#define LINK_UP_TIMEOUT                      HZ
> +#define LINK_RETRAIN_TIMEOUT         HZ
>  
>  #define INTX_NUM                     4
>  
> @@ -99,11 +100,44 @@ static bool altera_pcie_link_is_up(struct altera_pcie 
> *pcie)
>       return !!((cra_readl(pcie, RP_LTSSM) & RP_LTSSM_MASK) == LTSSM_L0);
>  }
>  
> +static void altera_wait_link_retrain(struct pci_dev *dev)
> +{
> +     u16 reg16;
> +     unsigned long start_jiffies;
> +     struct altera_pcie *pcie = dev->bus->sysdata;
> +
> +     /* Wait for link training end. */
> +     start_jiffies = jiffies;
> +     for (;;) {
> +             pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &reg16);
> +             if (!(reg16 & PCI_EXP_LNKSTA_LT))
> +                     break;
> +
> +             if (time_after(jiffies, start_jiffies + LINK_RETRAIN_TIMEOUT)) {
> +                     dev_err(&pcie->pdev->dev, "link retrain timeout\n");
> +                     break;
> +             }
> +             udelay(100);
> +     }
> +
> +     /* Wait for link is up */
> +     start_jiffies = jiffies;
> +     for (;;) {
> +             if (altera_pcie_link_is_up(pcie))
> +                     break;
> +
> +             if (time_after(jiffies, start_jiffies + LINK_UP_TIMEOUT)) {
> +                     dev_err(&pcie->pdev->dev, "link up timeout\n");
> +                     break;
> +             }
> +             udelay(100);
> +     }
> +}
> +
>  static void altera_pcie_retrain(struct pci_dev *dev)
>  {
>       u16 linkcap, linkstat;
>       struct altera_pcie *pcie = dev->bus->sysdata;
> -     int timeout =  0;
>  
>       if (!altera_pcie_link_is_up(pcie))
>               return;
> @@ -121,12 +155,7 @@ static void altera_pcie_retrain(struct pci_dev *dev)
>       if ((linkstat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB) {
>               pcie_capability_set_word(dev, PCI_EXP_LNKCTL,
>                                        PCI_EXP_LNKCTL_RL);
> -             while (!altera_pcie_link_is_up(pcie)) {
> -                     timeout++;
> -                     if (timeout > LINK_UP_TIMEOUT)
> -                             break;
> -                     udelay(5);
> -             }
> +             altera_wait_link_retrain(dev);
>       }
>  }
>  DECLARE_PCI_FIXUP_EARLY(0x1172, PCI_ANY_ID, altera_pcie_retrain);
> -- 
> 1.8.2.1
> 
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