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Date: Fri, 24 Apr 2009 13:11:10 +0900
From: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To: Andrew Patterson <andrew.patterson@...com>
CC: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
jbarnes@...tuousgeek.org
Subject: Re: [PATCH v3] PCI: Add support for turning PCIe ECRC on or off
Looks good to me.
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Andrew Patterson wrote:
> PCI: Add support for turning PCIe ECRC on or off
>
> Adds support for PCI Express transaction layer end-to-end CRC checking
> (ECRC). This patch will enable/disable ECRC checking by setting/clearing
> the ECRC Check Enable and/or ECRC Generation Enable bits for devices that
> support ECRC.
>
> The ECRC setting is controlled by the "pci=ecrc=<policy>" command-line
> option. If this option is not set or is set to 'bios", the enable and
> generation bits are left in whatever state that firmware/BIOS set them to.
> The "off" setting turns them off, and the "on" option turns them on (if the
> device supports it).
>
> Turning ECRC on or off can be a data integrity versus performance
> tradeoff. In theory, turning it on will catch more data errors, turning
> it off means possibly better performance since CRC does not need to be
> calculated by the PCIe hardware and packet sizes are reduced.
>
> Signed-off-by: Andrew Patterson <andrew.patterson@...com>
> ---
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 1754fed..56cdd5f 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1769,6 +1769,12 @@ and is between 256 and 4096 characters. It is defined in the file
> PAGE_SIZE is used as alignment.
> PCI-PCI bridge can be specified, if resource
> windows need to be expanded.
> + ecrc= Enable/disable PCIe ECRC (transaction layer
> + end-to-end CRC checking).
> + bios: Use BIOS/firmware settings. This is the
> + the default.
> + off: Turn ECRC off
> + on: Turn ECRC on.
>
> pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
> Management.
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 59569b8..65e8a53 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2555,6 +2555,8 @@ static int __init pci_setup(char *str)
> } else if (!strncmp(str, "resource_alignment=", 19)) {
> pci_set_resource_alignment_param(str + 19,
> strlen(str + 19));
> + } else if (!strncmp(str, "ecrc=", 5)) {
> + pcie_ecrc_get_policy(str + 5);
> } else {
> printk(KERN_ERR "PCI: Unknown option `%s'\n",
> str);
> diff --git a/drivers/pci/pcie/aer/Kconfig b/drivers/pci/pcie/aer/Kconfig
> index c3bde58..db4cb95 100644
> --- a/drivers/pci/pcie/aer/Kconfig
> +++ b/drivers/pci/pcie/aer/Kconfig
> @@ -10,3 +10,16 @@ config PCIEAER
> This enables PCI Express Root Port Advanced Error Reporting
> (AER) driver support. Error reporting messages sent to Root
> Port will be handled by PCI Express AER driver.
> +
> +
> +#
> +# PCI Express ECRC
> +#
> +config PCIE_ECRC
> + bool "PCI Express ECRC settings control"
> + depends on PCIEAER
> + help
> + Used to override firmware/bios settings for PCI Express ECRC
> + (transaction layer end-to-end CRC checking).
> +
> + When in doubt, say N.
> diff --git a/drivers/pci/pcie/aer/Makefile b/drivers/pci/pcie/aer/Makefile
> index 8da3bd8..7f93411 100644
> --- a/drivers/pci/pcie/aer/Makefile
> +++ b/drivers/pci/pcie/aer/Makefile
> @@ -4,6 +4,8 @@
>
> obj-$(CONFIG_PCIEAER) += aerdriver.o
>
> +obj-$(CONFIG_PCIE_ECRC) += ecrc.o
> +
> aerdriver-objs := aerdrv_errprint.o aerdrv_core.o aerdrv.o
> aerdriver-$(CONFIG_ACPI) += aerdrv_acpi.o
>
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
> index 307452f..dd3829e 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -113,15 +113,17 @@ static void set_device_error_reporting(struct pci_dev *dev, void *data)
> {
> bool enable = *((bool *)data);
>
> - if (dev->pcie_type != PCIE_RC_PORT &&
> - dev->pcie_type != PCIE_SW_UPSTREAM_PORT &&
> - dev->pcie_type != PCIE_SW_DOWNSTREAM_PORT)
> - return;
> + if (dev->pcie_type == PCIE_RC_PORT ||
> + dev->pcie_type == PCIE_SW_UPSTREAM_PORT ||
> + dev->pcie_type == PCIE_SW_DOWNSTREAM_PORT) {
> + if (enable)
> + pci_enable_pcie_error_reporting(dev);
> + else
> + pci_disable_pcie_error_reporting(dev);
> + }
>
> if (enable)
> - pci_enable_pcie_error_reporting(dev);
> - else
> - pci_disable_pcie_error_reporting(dev);
> + pcie_set_ecrc_checking(dev);
> }
>
> /**
> diff --git a/drivers/pci/pcie/aer/ecrc.c b/drivers/pci/pcie/aer/ecrc.c
> new file mode 100644
> index 0000000..ece97df
> --- /dev/null
> +++ b/drivers/pci/pcie/aer/ecrc.c
> @@ -0,0 +1,131 @@
> +/*
> + * Enables/disables PCIe ECRC checking.
> + *
> + * (C) Copyright 2009 Hewlett-Packard Development Company, L.P.
> + * Andrew Patterson <andrew.patterson@...com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
> + * 02111-1307, USA.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/pci.h>
> +#include <linux/pci_regs.h>
> +#include <linux/errno.h>
> +#include "../../pci.h"
> +
> +#define ECRC_POLICY_DEFAULT 0 /* ECRC set by BIOS */
> +#define ECRC_POLICY_OFF 1 /* ECRC off for performance */
> +#define ECRC_POLICY_ON 2 /* ECRC on for data integrity */
> +
> +static int ecrc_policy = ECRC_POLICY_DEFAULT;
> +
> +static const char *ecrc_policy_str[] = {
> + [ECRC_POLICY_DEFAULT] = "bios",
> + [ECRC_POLICY_OFF] = "off",
> + [ECRC_POLICY_ON] = "on"
> +};
> +
> +/**
> + * enable_ercr_checking - enable PCIe ECRC checking for a device
> + * @dev: the PCI device
> + *
> + * Returns 0 on success, or negative on failure.
> + */
> +static int enable_ecrc_checking(struct pci_dev *dev)
> +{
> + int pos;
> + u32 reg32;
> +
> + if (!dev->is_pcie)
> + return -ENODEV;
> +
> + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
> + if (!pos)
> + return -ENODEV;
> +
> + pci_read_config_dword(dev, pos + PCI_ERR_CAP, ®32);
> + if (reg32 & PCI_ERR_CAP_ECRC_GENC)
> + reg32 |= PCI_ERR_CAP_ECRC_GENE;
> + if (reg32 & PCI_ERR_CAP_ECRC_CHKC)
> + reg32 |= PCI_ERR_CAP_ECRC_CHKE;
> + pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
> +
> + return 0;
> +}
> +
> +/**
> + * disable_ercr_checking - disables PCIe ECRC checking for a device
> + * @dev: the PCI device
> + *
> + * Returns 0 on success, or negative on failure.
> + */
> +static int disable_ecrc_checking(struct pci_dev *dev)
> +{
> + int pos;
> + u32 reg32;
> +
> + if (!dev->is_pcie)
> + return -ENODEV;
> +
> + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
> + if (!pos)
> + return -ENODEV;
> +
> + pci_read_config_dword(dev, pos + PCI_ERR_CAP, ®32);
> + reg32 &= ~(PCI_ERR_CAP_ECRC_GENE | PCI_ERR_CAP_ECRC_CHKE);
> + pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
> +
> + return 0;
> +}
> +
> +/**
> + * pcie_set_ecrc_checking - set/unset PCIe ECRC checking for a device based on global policy
> + * @dev: the PCI device
> + */
> +void pcie_set_ecrc_checking(struct pci_dev *dev)
> +{
> + switch (ecrc_policy) {
> + case ECRC_POLICY_DEFAULT:
> + return;
> + case ECRC_POLICY_OFF:
> + disable_ecrc_checking(dev);
> + break;
> + case ECRC_POLICY_ON:
> + enable_ecrc_checking(dev);;
> + break;
> + default:
> + return;
> + }
> +}
> +
> +/**
> + * pcie_ecrc_get_policy - parse kernel command-line ecrc option
> + */
> +void pcie_ecrc_get_policy(char *str)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(ecrc_policy_str); i++)
> + if (!strncmp(str, ecrc_policy_str[i],
> + strlen(ecrc_policy_str[i])))
> + break;
> + if (i >= ARRAY_SIZE(ecrc_policy_str))
> + return;
> +
> + ecrc_policy = i;
> +}
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 6fb335b..0a25ccc 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -874,6 +874,17 @@ static inline int pcie_aspm_enabled(void)
> extern int pcie_aspm_enabled(void);
> #endif
>
> +#ifndef CONFIG_PCIE_ECRC
> +static inline void pcie_set_ecrc_checking(struct pci_dev *dev)
> +{
> + return;
> +}
> +static inline void pcie_ecrc_get_policy(char *str) {};
> +#else
> +extern void pcie_set_ecrc_checking(struct pci_dev *dev);
> +extern void pcie_ecrc_get_policy(char *str);
> +#endif
> +
> #define pci_enable_msi(pdev) pci_enable_msi_block(pdev, 1)
>
> #ifdef CONFIG_HT_IRQ
>
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