Support for PCI Express reset type in EEH

By default, EEH does what's known as a "hot reset" during error recovery of a PCI Express device.  We've found a case where the device needs a "fundamental reset" to recover properly.  The current PCI error recovery and EEH frameworks do not support this distinction.

The attached patch (courtesy of Richard Lary) implements a reset type callback that can be used to determine what type of reset a device requires.  It is backwards compatible with all other drivers that implement PCI error recovery callbacks.  Only drivers that require a fundamental reset need to be changed.  So far we're only aware of one driver that has the requirement (qla2xxx).  The patch touches mostly EEH and pseries code, but does require a couple of minor additions to the overall PCI error recovery framework.

Signed-off-by: Mike Mason <mmlnx@us.ibm.com>

This patch was simultaneously submitted to Red Hat for review.  As a result of that review, I'm withdrawing this patch and will submit a new version shortly.

Mike

Mike Mason wrote:
> By default, EEH does what's known as a "hot reset" during error recovery 
> of a PCI Express device.  We've found a case where the device needs a 
> "fundamental reset" to recover properly.  The current PCI error recovery 
> and EEH frameworks do not support this distinction.
> 
> The attached patch (courtesy of Richard Lary) implements a reset type 
> callback that can be used to determine what type of reset a device 
> requires.  It is backwards compatible with all other drivers that 
> implement PCI error recovery callbacks.  Only drivers that require a 
> fundamental reset need to be changed.  So far we're only aware of one 
> driver that has the requirement (qla2xxx).  The patch touches mostly EEH 
> and pseries code, but does require a couple of minor additions to the 
> overall PCI error recovery framework.
> 
> Signed-off-by: Mike Mason <mmlnx@us.ibm.com>
> 
> --- a/arch/powerpc/include/asm/ppc-pci.h    2009-06-09 
> 20:05:27.000000000 -0700
> +++ b/arch/powerpc/include/asm/ppc-pci.h    2009-07-13 
> 16:12:31.000000000 -0700
> @@ -90,7 +90,9 @@ int rtas_pci_enable(struct pci_dn *pdn,
> *
> * Returns a non-zero value if the reset failed.
> */
> -int rtas_set_slot_reset (struct pci_dn *);
> +#define HOT_RESET        1
> +#define FUNDAMENTAL_RESET    3
> +int rtas_set_slot_reset (struct pci_dn *, int reset_type);
> int eeh_wait_for_slot_status(struct pci_dn *pdn, int max_wait_msecs);
> 
> /** --- a/arch/powerpc/platforms/pseries/eeh.c    2009-06-09 
> 20:05:27.000000000 -0700
> +++ b/arch/powerpc/platforms/pseries/eeh.c    2009-07-13 
> 16:27:27.000000000 -0700
> @@ -666,7 +666,7 @@ rtas_pci_enable(struct pci_dn *pdn, int
> /**
> * rtas_pci_slot_reset - raises/lowers the pci #RST line
> * @pdn pci device node
> - * @state: 1/0 to raise/lower the #RST
> + * @state: 1/3/0 to raise hot-reset/fundamental-reset/lower the #RST
> *
> * Clear the EEH-frozen condition on a slot.  This routine
> * asserts the PCI #RST line if the 'state' argument is '1',
> @@ -742,9 +742,9 @@ int pcibios_set_pcie_reset_state(struct
> *  Return 0 if success, else a non-zero value.
> */
> 
> -static void __rtas_set_slot_reset(struct pci_dn *pdn)
> +static void __rtas_set_slot_reset(struct pci_dn *pdn, int reset_type)
> {
> -    rtas_pci_slot_reset (pdn, 1);
> +    rtas_pci_slot_reset (pdn, reset_type);
> 
>     /* The PCI bus requires that the reset be held high for at least
>      * a 100 milliseconds. We wait a bit longer 'just in case'.  */
> @@ -766,13 +766,13 @@ static void __rtas_set_slot_reset(struct
>     msleep (PCI_BUS_SETTLE_TIME_MSEC);
> }
> 
> -int rtas_set_slot_reset(struct pci_dn *pdn)
> +int rtas_set_slot_reset(struct pci_dn *pdn, int reset_type)
> {
>     int i, rc;
> 
>     /* Take three shots at resetting the bus */
>     for (i=0; i<3; i++) {
> -        __rtas_set_slot_reset(pdn);
> +        __rtas_set_slot_reset(pdn, reset_type);
> 
>         rc = eeh_wait_for_slot_status(pdn, PCI_BUS_RESET_WAIT_MSEC);
>         if (rc == 0)
> --- a/arch/powerpc/platforms/pseries/eeh_driver.c    2009-07-13 
> 14:25:24.000000000 -0700
> +++ b/arch/powerpc/platforms/pseries/eeh_driver.c    2009-07-13 
> 16:39:16.000000000 -0700
> @@ -115,6 +115,34 @@ static void eeh_enable_irq(struct pci_de
> 
> /* ------------------------------------------------------- */
> /**
> + * eeh_query_reset_type - query each device driver for reset type
> + *
> + * Query each device driver for special reset type if required
> + * merge the device driver responses. Cumulative response
> + * passed back in "userdata".
> + */
> +
> +static int eeh_query_reset_type(struct pci_dev *dev, void *userdata)
> +{
> +    enum pci_ers_result rc, *res = userdata;
> +    struct pci_driver *driver = dev->driver;
> +
> +    if (!driver)
> +        return 0;
> +
> +    if (!driver->err_handler ||
> +        !driver->err_handler->reset_type)
> +        return 0;
> +
> +    rc = driver->err_handler->reset_type (dev);
> +
> +    /* A driver that needs a special reset trumps all others */
> +    if (rc == PCI_ERS_RESULT_FUNDAMENTAL_RESET ) *res = rc;
> +
> +    return 0;
> +}
> +
> +/**
> * eeh_report_error - report pci error to each device driver
> * * Report an EEH error to each device driver, collect up and @@ -282,9 
> +310,12 @@ static int eeh_report_failure(struct pci
> * @pe_dn: pointer to a "Partionable Endpoint" device node.
> *            This is the top-level structure on which pci
> *            bus resets can be performed.
> + *
> + * reset_type: some devices may require type other than default hot reset.
> */
> 
> -static int eeh_reset_device (struct pci_dn *pe_dn, struct pci_bus *bus)
> +static int eeh_reset_device (struct pci_dn *pe_dn, struct pci_bus *bus,
> +                 int reset_type)
> {
>     struct device_node *dn;
>     int cnt, rc;
> @@ -298,7 +329,7 @@ static int eeh_reset_device (struct pci_
>     /* Reset the pci controller. (Asserts RST#; resets config space).
>      * Reconfigure bridges and devices. Don't try to bring the system
>      * up if the reset failed for some reason. */
> -    rc = rtas_set_slot_reset(pe_dn);
> +    rc = rtas_set_slot_reset(pe_dn, reset_type);
>     if (rc)
>         return rc;
> 
> @@ -343,6 +374,7 @@ struct pci_dn * handle_eeh_events (struc
>     struct pci_dn *frozen_pdn;
>     struct pci_bus *frozen_bus;
>     int rc = 0;
> +    int reset_type = HOT_RESET;
>     enum pci_ers_result result = PCI_ERS_RESULT_NONE;
>     const char *location, *pci_str, *drv_str;
> 
> @@ -400,10 +432,16 @@ struct pci_dn * handle_eeh_events (struc
> 
>     /* Walk the various device drivers attached to this slot through
>      * a reset sequence, giving each an opportunity to do what it needs
> -     * to accomplish the reset.  Each child gets a report of the
> -     * status ... if any child can't handle the reset, then the entire
> -     * slot is dlpar removed and added.
> +     * to accomplish the reset.  Query device driver for special reset
> +     * requiements. Report eeh error to each child with cumulative
> +     * result status... if any child can't handle the reset,
> +     * then the entire slot is dlpar removed and added.
>      */
> +    pci_walk_bus(frozen_bus, eeh_query_reset_type, &result);
> +    if ( result == PCI_ERS_RESULT_FUNDAMENTAL_RESET )
> +        reset_type = FUNDAMENTAL_RESET;
> +
> +    result = PCI_ERS_RESULT_NONE;
>     pci_walk_bus(frozen_bus, eeh_report_error, &result);
> 
>     /* Get the current PCI slot state. This can take a long time,
> @@ -425,7 +463,8 @@ struct pci_dn * handle_eeh_events (struc
>      * go down willingly, without panicing the system.
>      */
>     if (result == PCI_ERS_RESULT_NONE) {
> -        rc = eeh_reset_device(frozen_pdn, frozen_bus);
> +        rc = eeh_reset_device(frozen_pdn, frozen_bus, reset_type);
> +
>         if (rc) {
>             printk(KERN_WARNING "EEH: Unable to reset, rc=%d\n", rc);
>             goto hard_fail;
> @@ -466,7 +505,7 @@ struct pci_dn * handle_eeh_events (struc
> 
>     /* If any device called out for a reset, then reset the slot */
>     if (result == PCI_ERS_RESULT_NEED_RESET) {
> -        rc = eeh_reset_device(frozen_pdn, NULL);
> +        rc = eeh_reset_device(frozen_pdn, NULL, reset_type);
>         if (rc) {
>             printk(KERN_WARNING "EEH: Cannot reset, rc=%d\n", rc);
>             goto hard_fail;
> --- a/include/linux/pci.h    2009-07-13 14:25:37.000000000 -0700
> +++ b/include/linux/pci.h    2009-07-13 16:12:31.000000000 -0700
> @@ -446,6 +446,9 @@ enum pci_ers_result {
> 
>     /* Device driver is fully recovered and operational */
>     PCI_ERS_RESULT_RECOVERED = (__force pci_ers_result_t) 5,
> +
> +    /* Device driver requires fundamental reset to recover */
> +    PCI_ERS_RESULT_FUNDAMENTAL_RESET = (__force pci_ers_result_t) 6,
> };
> 
> /* PCI bus error event callbacks */
> @@ -465,6 +468,9 @@ struct pci_error_handlers {
> 
>     /* Device driver may resume normal operations */
>     void (*resume)(struct pci_dev *dev);
> +
> +    /* PCI slot requires special reset type for recovery */
> +    pci_ers_result_t (*reset_type)(struct pci_dev *dev);
> };
> 
> /* ---------------------------------------------------------------- */
> --- a/arch/powerpc/include/asm/ppc-pci.h    2009-06-09 
> 20:05:27.000000000 -0700
> +++ b/arch/powerpc/include/asm/ppc-pci.h    2009-07-13 
> 16:12:31.000000000 -0700
> @@ -90,7 +90,9 @@ int rtas_pci_enable(struct pci_dn *pdn,
> *
> * Returns a non-zero value if the reset failed.
> */
> -int rtas_set_slot_reset (struct pci_dn *);
> +#define HOT_RESET        1
> +#define FUNDAMENTAL_RESET    3
> +int rtas_set_slot_reset (struct pci_dn *, int reset_type);
> int eeh_wait_for_slot_status(struct pci_dn *pdn, int max_wait_msecs);
> 
> /** --- a/arch/powerpc/platforms/pseries/eeh.c    2009-06-09 
> 20:05:27.000000000 -0700
> +++ b/arch/powerpc/platforms/pseries/eeh.c    2009-07-13 
> 16:27:27.000000000 -0700
> @@ -666,7 +666,7 @@ rtas_pci_enable(struct pci_dn *pdn, int
> /**
> * rtas_pci_slot_reset - raises/lowers the pci #RST line
> * @pdn pci device node
> - * @state: 1/0 to raise/lower the #RST
> + * @state: 1/3/0 to raise hot-reset/fundamental-reset/lower the #RST
> *
> * Clear the EEH-frozen condition on a slot.  This routine
> * asserts the PCI #RST line if the 'state' argument is '1',
> @@ -742,9 +742,9 @@ int pcibios_set_pcie_reset_state(struct
> *  Return 0 if success, else a non-zero value.
> */
> 
> -static void __rtas_set_slot_reset(struct pci_dn *pdn)
> +static void __rtas_set_slot_reset(struct pci_dn *pdn, int reset_type)
> {
> -    rtas_pci_slot_reset (pdn, 1);
> +    rtas_pci_slot_reset (pdn, reset_type);
> 
>     /* The PCI bus requires that the reset be held high for at least
>      * a 100 milliseconds. We wait a bit longer 'just in case'.  */
> @@ -766,13 +766,13 @@ static void __rtas_set_slot_reset(struct
>     msleep (PCI_BUS_SETTLE_TIME_MSEC);
> }
> 
> -int rtas_set_slot_reset(struct pci_dn *pdn)
> +int rtas_set_slot_reset(struct pci_dn *pdn, int reset_type)
> {
>     int i, rc;
> 
>     /* Take three shots at resetting the bus */
>     for (i=0; i<3; i++) {
> -        __rtas_set_slot_reset(pdn);
> +        __rtas_set_slot_reset(pdn, reset_type);
> 
>         rc = eeh_wait_for_slot_status(pdn, PCI_BUS_RESET_WAIT_MSEC);
>         if (rc == 0)
> --- a/arch/powerpc/platforms/pseries/eeh_driver.c    2009-07-13 
> 14:25:24.000000000 -0700
> +++ b/arch/powerpc/platforms/pseries/eeh_driver.c    2009-07-13 
> 16:39:16.000000000 -0700
> @@ -115,6 +115,34 @@ static void eeh_enable_irq(struct pci_de
> 
> /* ------------------------------------------------------- */
> /**
> + * eeh_query_reset_type - query each device driver for reset type
> + *
> + * Query each device driver for special reset type if required
> + * merge the device driver responses. Cumulative response
> + * passed back in "userdata".
> + */
> +
> +static int eeh_query_reset_type(struct pci_dev *dev, void *userdata)
> +{
> +    enum pci_ers_result rc, *res = userdata;
> +    struct pci_driver *driver = dev->driver;
> +
> +    if (!driver)
> +        return 0;
> +
> +    if (!driver->err_handler ||
> +        !driver->err_handler->reset_type)
> +        return 0;
> +
> +    rc = driver->err_handler->reset_type (dev);
> +
> +    /* A driver that needs a special reset trumps all others */
> +    if (rc == PCI_ERS_RESULT_FUNDAMENTAL_RESET ) *res = rc;
> +
> +    return 0;
> +}
> +
> +/**
> * eeh_report_error - report pci error to each device driver
> * * Report an EEH error to each device driver, collect up and @@ -282,9 
> +310,12 @@ static int eeh_report_failure(struct pci
> * @pe_dn: pointer to a "Partionable Endpoint" device node.
> *            This is the top-level structure on which pci
> *            bus resets can be performed.
> + *
> + * reset_type: some devices may require type other than default hot reset.
> */
> 
> -static int eeh_reset_device (struct pci_dn *pe_dn, struct pci_bus *bus)
> +static int eeh_reset_device (struct pci_dn *pe_dn, struct pci_bus *bus,
> +                 int reset_type)
> {
>     struct device_node *dn;
>     int cnt, rc;
> @@ -298,7 +329,7 @@ static int eeh_reset_device (struct pci_
>     /* Reset the pci controller. (Asserts RST#; resets config space).
>      * Reconfigure bridges and devices. Don't try to bring the system
>      * up if the reset failed for some reason. */
> -    rc = rtas_set_slot_reset(pe_dn);
> +    rc = rtas_set_slot_reset(pe_dn, reset_type);
>     if (rc)
>         return rc;
> 
> @@ -343,6 +374,7 @@ struct pci_dn * handle_eeh_events (struc
>     struct pci_dn *frozen_pdn;
>     struct pci_bus *frozen_bus;
>     int rc = 0;
> +    int reset_type = HOT_RESET;
>     enum pci_ers_result result = PCI_ERS_RESULT_NONE;
>     const char *location, *pci_str, *drv_str;
> 
> @@ -400,10 +432,16 @@ struct pci_dn * handle_eeh_events (struc
> 
>     /* Walk the various device drivers attached to this slot through
>      * a reset sequence, giving each an opportunity to do what it needs
> -     * to accomplish the reset.  Each child gets a report of the
> -     * status ... if any child can't handle the reset, then the entire
> -     * slot is dlpar removed and added.
> +     * to accomplish the reset.  Query device driver for special reset
> +     * requiements. Report eeh error to each child with cumulative
> +     * result status... if any child can't handle the reset,
> +     * then the entire slot is dlpar removed and added.
>      */
> +    pci_walk_bus(frozen_bus, eeh_query_reset_type, &result);
> +    if ( result == PCI_ERS_RESULT_FUNDAMENTAL_RESET )
> +        reset_type = FUNDAMENTAL_RESET;
> +
> +    result = PCI_ERS_RESULT_NONE;
>     pci_walk_bus(frozen_bus, eeh_report_error, &result);
> 
>     /* Get the current PCI slot state. This can take a long time,
> @@ -425,7 +463,8 @@ struct pci_dn * handle_eeh_events (struc
>      * go down willingly, without panicing the system.
>      */
>     if (result == PCI_ERS_RESULT_NONE) {
> -        rc = eeh_reset_device(frozen_pdn, frozen_bus);
> +        rc = eeh_reset_device(frozen_pdn, frozen_bus, reset_type);
> +
>         if (rc) {
>             printk(KERN_WARNING "EEH: Unable to reset, rc=%d\n", rc);
>             goto hard_fail;
> @@ -466,7 +505,7 @@ struct pci_dn * handle_eeh_events (struc
> 
>     /* If any device called out for a reset, then reset the slot */
>     if (result == PCI_ERS_RESULT_NEED_RESET) {
> -        rc = eeh_reset_device(frozen_pdn, NULL);
> +        rc = eeh_reset_device(frozen_pdn, NULL, reset_type);
>         if (rc) {
>             printk(KERN_WARNING "EEH: Cannot reset, rc=%d\n", rc);
>             goto hard_fail;
> --- a/include/linux/pci.h    2009-07-13 14:25:37.000000000 -0700
> +++ b/include/linux/pci.h    2009-07-13 16:12:31.000000000 -0700
> @@ -446,6 +446,9 @@ enum pci_ers_result {
> 
>     /* Device driver is fully recovered and operational */
>     PCI_ERS_RESULT_RECOVERED = (__force pci_ers_result_t) 5,
> +
> +    /* Device driver requires fundamental reset to recover */
> +    PCI_ERS_RESULT_FUNDAMENTAL_RESET = (__force pci_ers_result_t) 6,
> };
> 
> /* PCI bus error event callbacks */
> @@ -465,6 +468,9 @@ struct pci_error_handlers {
> 
>     /* Device driver may resume normal operations */
>     void (*resume)(struct pci_dev *dev);
> +
> +    /* PCI slot requires special reset type for recovery */
> +    pci_ers_result_t (*reset_type)(struct pci_dev *dev);
> };
> 
> /* ---------------------------------------------------------------- */
> 
>