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Subject: Re: [PATCH v4] PCI: Add quirk for preventing bus reset on TI C667X
To:     =?UTF-8?Q?Antti_J=c3=a4rvinen?= <antti.jarvinen@gmail.com>,
        <helgaas@kernel.org>
CC:     <alex.williamson@redhat.com>, <bhelgaas@google.com>,
        <kw@linux.com>, <linux-kernel@vger.kernel.org>,
        <linux-pci@vger.kernel.org>
References: <20210312210917.GA2290948@bjorn-Precision-5520>
 <20210315102606.17153-1-antti.jarvinen@gmail.com>
From:   Kishon Vijay Abraham I <kishon@ti.com>
Message-ID: <d7753802-4f7f-7470-1add-de44817eff5c@ti.com>
Date:   Mon, 19 Apr 2021 18:14:44 +0530
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On 15/03/21 3:56 pm, Antti Järvinen wrote:
> Some TI KeyStone C667X devices do not support bus/hot reset. Its PCIESS
> automatically disables LTSSM when secondary bus reset is received and
> device stops working. Prevent bus reset by adding quirk_no_bus_reset to
> the device. With this change device can be assigned to VMs with VFIO,
> but it will leak state between VMs.
> 
> Reference: https://e2e.ti.com/support/processors/f/791/t/954382
> Signed-off-by: Antti Järvinen <antti.jarvinen@gmail.com>

Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---
>  drivers/pci/quirks.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 653660e3ba9e..d9201ad1ca39 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3578,6 +3578,16 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0034, quirk_no_bus_reset);
>   */
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_CAVIUM, 0xa100, quirk_no_bus_reset);
>  
> +/*
> + * Some TI keystone C667X devices do no support bus/hot reset.
> + * Its PCIESS automatically disables LTSSM when secondary bus reset is
> + * received and device stops working. Prevent bus reset by adding
> + * quirk_no_bus_reset to the device. With this change device can be
> + * assigned to VMs with VFIO, but it will leak state between VMs.
> + * Reference https://e2e.ti.com/support/processors/f/791/t/954382
> + */
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_TI, 0xb005, quirk_no_bus_reset);
> +
>  static void quirk_no_pm_reset(struct pci_dev *dev)
>  {
>  	/*
>