linux-kernel - Re: [PATCH 3/3] PCI/AER: Provide reset

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Message-ID: <51A621E2.2050202@hp.com>
Date:	Wed, 29 May 2013 15:42:27 +0000
From:	"Pearson, Greg" <greg.pearson@...com>
To:	"Dall, Elizabeth J (MCLinux)" <betty.dall@...com>
CC:	"rjw@...k.pl" <rjw@...k.pl>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"ying.huang@...el.com" <ying.huang@...el.com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: Re: [PATCH 3/3] PCI/AER: Provide reset_link for firmware first root
 port

On 05/28/2013 12:48 PM, Betty Dall wrote:
> The firmware first path does not install the aerdrv root port
> service driver, so the firmware first root port does not have
> a reset_link callback. When a firmware first root port does not have
> a reset_link callback, use a new default reset_link similar to what
> we already do for the default_downstream_reset_link(). The firmware
> first default reset_link brings the root port out of SBR if firmware
> left it in SBR.
>
> Signed-off-by: Betty Dall <betty.dall@...com>
> ---
>
>   drivers/pci/pcie/aer/aerdrv_core.c |   37 ++++++++++++++++++++++++++++++++++++
>   1 files changed, 37 insertions(+), 0 deletions(-)
>
>
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
> index 8ec8b4f..6862fe3 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -413,6 +413,40 @@ static pci_ers_result_t default_downstream_reset_link(struct pci_dev *dev)
>   	return PCI_ERS_RESULT_RECOVERED;
>   }
>   
> +/**
> + * default_ff_root_port_reset_link - default reset function for firmware
> + *		first Root Port
> + * @dev: pointer to root port's pci_dev data structure
> + *
> + * Invoked when performing link reset at Root Port w/ no aer driver.
> + * This happens through the firmware first path. Firmware may leave
> + * the Root Port in SBR and it is the OS responsiblity to bring it out
> + * of SBR.
> + */
> +static pci_ers_result_t default_ff_root_port_reset_link(struct pci_dev *dev)
> +{
> +	u16 p2p_ctrl;
> +
> +	/* Read Secondary Bus Reset */
> +	pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &p2p_ctrl);
> +	p2p_ctrl |= PCI_BRIDGE_CTL_BUS_RESET;

Remove "p2p_ctrl |= PCI_BRIDGE_CTL_BUS_RESET;" otherwise the following 
conditional is always taken.

--
Greg

> +
> +	/* De-assert Secondary Bus Reset, if it is set */
> +	if (p2p_ctrl & PCI_BRIDGE_CTL_BUS_RESET) {
> +		p2p_ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
> +		pci_write_config_word(dev, PCI_BRIDGE_CONTROL, p2p_ctrl);
> +
> +		/*
> +		 * System software must wait for at least 100ms from the end
> +		 * of a reset of one or more device before it is permitted
> +		 * to issue Configuration Requests to those devices.
> +		 */
> +		msleep(200);
> +		dev_dbg(&dev->dev, "Root Port link has been reset\n");
> +	}
> +	return PCI_ERS_RESULT_RECOVERED;
> +}
> +
>   static int find_aer_service_iter(struct device *device, void *data)
>   {
>   	struct pcie_port_service_driver *service_driver, **drv;
> @@ -460,6 +494,9 @@ static pci_ers_result_t reset_link(struct pci_dev *dev)
>   		status = driver->reset_link(udev);
>   	} else if (pci_pcie_type(udev) == PCI_EXP_TYPE_DOWNSTREAM) {
>   		status = default_downstream_reset_link(udev);
> +	} else if (pci_pcie_type(udev) == PCI_EXP_TYPE_ROOT_PORT &&
> +		pcie_aer_get_firmware_first(udev)) {
> +		status = default_ff_root_port_reset_link(udev);
>   	} else {
>   		dev_printk(KERN_DEBUG, &dev->dev,
>   			"no link-reset support at upstream device %s\n",
> --
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