linux-kernel - Re: [PATCH 2/2] PCI: Avoid bus reset for Cavium cn8xxx root ports.

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Date:   Tue, 16 May 2017 22:14:40 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     David Daney <david.daney@...ium.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org
Cc:     Jon Masters <jcm@...hat.com>,
        Robert Richter <robert.richter@...ium.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] PCI: Avoid bus reset for Cavium cn8xxx root ports.

Hi,

On 16/05/2017 02:17, David Daney wrote:
> Root ports of cn8xxx do not function after bus reset when used with
> some e1000e and LSI HBA devices.  Add a quirk to prevent bus reset on
> these root ports.
I understand the bus reset would work along with a variety of other
child devices. I guess there is no way to be more accurate and forbid
the bus reset only when incompatible child devices are found?
> 
> Signed-off-by: David Daney <david.daney@...ium.com>
> ---
>  drivers/pci/quirks.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 085fb78..02cd847 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3347,6 +3347,14 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0032, quirk_no_bus_reset);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003c, quirk_no_bus_reset);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0033, quirk_no_bus_reset);
>  
> +/*
> + * Root port on some Cavium CN8xxx chips do not successfully complete
> + * a bus reset when used with certain types child devices.  Config
s/types /types of
Thanks

Eric
> + * space access to the child may quit responding.  Flag the root port
> + * as not supporting bus reset.
> + */
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_CAVIUM, 0xa100, quirk_no_bus_reset);
> +
>  static void quirk_no_pm_reset(struct pci_dev *dev)
>  {
>  	/*
>