linux-kernel - Re: [PATCH] PCI/ASPM: fix reverse ASPM L0s assignment of upstream and downstream

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Date:	Tue, 24 May 2016 06:53:33 -0500
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Ocean HY1 He <hehy1@...ovo.com>
Cc:	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"wangyijing@...wei.com" <wangyijing@...wei.com>,
	"luto@...nel.org" <luto@...nel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"prarit@...hat.com" <prarit@...hat.com>,
	"jcm@...hat.com" <jcm@...hat.com>,
	Nagananda Chumbalkar <nchumbalkar@...ovo.com>
Subject: Re: [PATCH] PCI/ASPM: fix reverse ASPM L0s assignment of upstream
 and downstream

Hi Ocean,

On Tue, May 24, 2016 at 06:29:44AM +0000, Ocean HY1 He wrote:
> In pcie_config_aspm_link(), when convert ASPM state to
> upstream/downstream ASPM register state, the upstream variable and
> dwsream variable are reversed. This causes PCI/E link enter ASPM L0s
> even it should be disabled and PCI/E endpoint may reset randomly.

Random resets of an endpoint sounds like a pretty bad problem.  Do you
have a bug report?  We've had lots of issues with ASPM; I wonder if
this could account for some of them.

> Signed-off-by: Ocean He <hehy1@...ovo.com>
> ---
>  drivers/pci/pcie/aspm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 2dfe7fd..3f8a44d 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -439,9 +439,9 @@ static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)
>  		return;
>  	/* Convert ASPM state to upstream/downstream ASPM register state */
>  	if (state & ASPM_STATE_L0S_UP)
> -		dwstream |= PCI_EXP_LNKCTL_ASPM_L0S;
> -	if (state & ASPM_STATE_L0S_DW)
>  		upstream |= PCI_EXP_LNKCTL_ASPM_L0S;
> +	if (state & ASPM_STATE_L0S_DW)
> +		dwstream |= PCI_EXP_LNKCTL_ASPM_L0S;
>  	if (state & ASPM_STATE_L1) {
>  		upstream |= PCI_EXP_LNKCTL_ASPM_L1;
>  		dwstream |= PCI_EXP_LNKCTL_ASPM_L1;
> -- 
> 1.8.3.1
> --
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