linux-kernel - Re: [PATCH 2/2] PCI: designware: let dw_pcie_link

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Message-ID: <2e9d2b8c-f4c3-aa6d-38be-314213db7727@synopsys.com>
Date:	Fri, 15 Jul 2016 16:10:24 +0100
From:	Joao Pinto <Joao.Pinto@...opsys.com>
To:	Jisheng Zhang <jszhang@...vell.com>, <jingoohan1@...il.com>,
	<pratyush.anand@...il.com>, <bhelgaas@...gle.com>
CC:	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/2] PCI: designware: let dw_pcie_link_up() beware of
 LTSSM training bit

Hi,

On 7/6/2016 11:59 AM, Jisheng Zhang wrote:
> The link may be UP but still in link training. In this case, we can't
> think the link is up and operating correctly. So we need to teach
> dw_pcie_link_up() beware of the PCIE_PHY_DEBUG_R1_LINK_IN_TRAINING bit.
> 
> This patch also rewrite PCIE_PHY_DEBUG_R1_LINK_UP definition so that
> it's consistent with other MACROS.
> 
> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> ---
>  drivers/pci/host/pcie-designware.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
> index 9df879a..29e10dd 100644
> --- a/drivers/pci/host/pcie-designware.c
> +++ b/drivers/pci/host/pcie-designware.c
> @@ -73,7 +73,8 @@
>  /* PCIe Port Logic registers */
>  #define PLR_OFFSET			0x700
>  #define PCIE_PHY_DEBUG_R1		(PLR_OFFSET + 0x2c)
> -#define PCIE_PHY_DEBUG_R1_LINK_UP	0x00000010
> +#define PCIE_PHY_DEBUG_R1_LINK_UP	(0x1 << 4)
> +#define PCIE_PHY_DEBUG_R1_LINK_IN_TRAINING	(0x1 << 29)

According to the databook bit 29 is inside a range that is dedicated to M-PCIe.
Have you checked bit 29 state by experience?

>  
>  /* Parameters for the waiting for link up routine */
>  #define LINK_WAIT_MAX_RETRIES		10
> @@ -417,7 +418,8 @@ int dw_pcie_link_up(struct pcie_port *pp)
>  		return pp->ops->link_up(pp);
>  
>  	val = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> -	return val & PCIE_PHY_DEBUG_R1_LINK_UP;
> +	return ((val & PCIE_PHY_DEBUG_R1_LINK_UP) &&
> +		(!(val & PCIE_PHY_DEBUG_R1_LINK_IN_TRAINING)));
>  }
>  
>  static int dw_pcie_msi_map(struct irq_domain *domain, unsigned int irq,
> 

Thanks,
Joao