linux-kernel - Re: [PATCH 1/2] IB/hfi1: Try slot reset before secondary bus reset

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Message-ID: <20180619214346.GD33049@bhelgaas-glaptop.roam.corp.google.com>
Date:   Tue, 19 Jun 2018 16:43:46 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Sinan Kaya <okaya@...eaurora.org>
Cc:     linux-pci@...r.kernel.org, sulrich@...eaurora.org,
        timur@...eaurora.org,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        "open list:HFI1 DRIVER" <linux-rdma@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        open list <linux-kernel@...r.kernel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Doug Ledford <dledford@...hat.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/2] IB/hfi1: Try slot reset before secondary bus reset

On Thu, Apr 19, 2018 at 03:56:23PM -0400, Sinan Kaya wrote:
> The infiniband adapter might be connected to a PCI hotplug slot. Performing
> secondary bus reset on a hotplug slot causes PCI link up/down interrupts.
> 
> Hotplug driver removes the device from system when a link down interrupt
> is observed and performs re-enumeration when link up interrupt is observed.
> 
> This conflicts with what this code is trying to do. Try secondary bus reset
> only if pci_reset_slot() fails/unsupported.

Hi Sinan,

We had a bunch of discussion here but not sure we ever reached a
consensus.  It did seem like we'd like to avoid putting hotplug
knowledge in drivers, though.  What do you think the path forward is?

> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/infiniband/hw/hfi1/pcie.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/pcie.c b/drivers/infiniband/hw/hfi1/pcie.c
> index 83d66e8..75f49e3 100644
> --- a/drivers/infiniband/hw/hfi1/pcie.c
> +++ b/drivers/infiniband/hw/hfi1/pcie.c
> @@ -908,7 +908,8 @@ static int trigger_sbr(struct hfi1_devdata *dd)
>  	 * delay after a reset is required.  Per spec requirements,
>  	 * the link is either working or not after that point.
>  	 */
> -	pci_reset_bridge_secondary_bus(dev->bus->self);
> +	if (pci_reset_slot(dev->slot))
> +		pci_reset_bridge_secondary_bus(dev->bus->self);
>  
>  	return 0;
>  }
> -- 
> 2.7.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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