Subject: Re: [PATCH v3 1/2] PCI: One more parameter to pci_set_pcie_reset_state()

From: Gavin Shan <[email-masked]>
Date: Mon, 23 Mar 2015 14:56:56 +1100

On Sun, Mar 22, 2015 at 09:34:33PM -0600, Alex Williamson wrote:
>On Mon, 2015-03-23 at 14:02 +1100, Gavin Shan wrote:
>> The patch adds one more parameter ("probe") to pci_set_pcie_reset_state(),
>> which allows to check if one particular PCI device can be resetted by the
>> function. The function will be reused to support PCI device specific methods
>> maintained in pci_dev_reset_methods[] in subsequent patch.
>> 
>> Cc: Brian King <[email-masked]>
>> Cc: Frank Haverkamp <[email-masked]>
>> Cc: Ian Munsie <[email-masked]>
>> Signed-off-by: Gavin Shan <[email-masked]>
>> ---
>> v3: Fix arguments of pci_set_pcie_reset_state() in cxl driver
>> v2: Reimplemented based on pci_set_pcie_reset_state()
>> ---
>>  arch/powerpc/kernel/eeh.c       | 14 ++++++++++----
>>  drivers/misc/cxl/pci.c          |  2 +-
>>  drivers/misc/genwqe/card_base.c |  9 +++++++--
>>  drivers/pci/pci.c               | 15 +++++++++------
>>  drivers/scsi/ipr.c              |  5 +++--
>>  include/linux/pci.h             |  5 +++--
>>  6 files changed, 33 insertions(+), 17 deletions(-)
>
>
>Argh, you're trying to make pci_set_pcie_reset_state() compatible with
>pci_dev_specific_reset(), so it can be called via pci_reset_function(),
>but the whole point of the pci_reset_function() interface is to reset a
>*single* function without disturbing anything else.  These patches make
>no effort at all to limit the set of affected devices to a single
>function and take great liberties using PCI_ANY_ID for vendors.  My take
>on the powerpc version of pcibios_set_pcie_reset_state() is that it's
>effectively a slot reset, so why not hook into the
>pci_reset_hotplug_slot() via the hotplug slot ops?  Please also use
>cover letters.  Thanks,
>

Yep, that's the point and intention of the patches. pcibios_set_pcie_reset_state()
isn't equal to pci_reset_hotplug_slot(). The later one depends on PCI slot, which
wasn't populated on PowerNV platform yet, but pcibios_set_pcie_reseet_state() doesn't.

The patchset depends on improved pcibios_set_pcie_reset_state(), which can be seen
from following linked. With it, we don't affect any PCI devices as the config space
is saved/restored accordingly before/after reset:

https://patchwork.ozlabs.org/patch/438598/

Sorry that I didn't use cover letter again. I'll have one next time always.

Thanks,
Gavin

>Alex
>
>> diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
>> index daa68a1..cd85c18 100644
>> --- a/arch/powerpc/kernel/eeh.c
>> +++ b/arch/powerpc/kernel/eeh.c
>> @@ -726,11 +726,14 @@ static void *eeh_restore_dev_state(void *data, void *userdata)
>>   * pcibios_set_pcie_slot_reset - Set PCI-E reset state
>>   * @dev: pci device struct
>>   * @state: reset state to enter
>> + * @probe: check if the device can take the reset
>>   *
>>   * Return value:
>>   * 	0 if success
>>   */
>> -int pcibios_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state)
>> +int pcibios_set_pcie_reset_state(struct pci_dev *dev,
>> +				 enum pcie_reset_state state,
>> +				 int probe)
>>  {
>>  	struct eeh_dev *edev = pci_dev_to_eeh_dev(dev);
>>  	struct eeh_pe *pe = eeh_dev_to_pe(edev);
>> @@ -738,9 +741,12 @@ int pcibios_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state stat
>>  	if (!pe) {
>>  		pr_err("%s: No PE found on PCI device %s\n",
>>  			__func__, pci_name(dev));
>> -		return -EINVAL;
>> +		return -ENOTTY;
>>  	}
>>  
>> +	if (probe)
>> +		return 0;
>> +
>>  	switch (state) {
>>  	case pcie_deassert_reset:
>>  		eeh_ops->reset(pe, EEH_RESET_DEACTIVATE);
>> @@ -762,8 +768,8 @@ int pcibios_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state stat
>>  		break;
>>  	default:
>>  		eeh_pe_state_clear(pe, EEH_PE_CFG_BLOCKED);
>> -		return -EINVAL;
>> -	};
>> +		return -ENOTTY;
>> +	}
>>  
>>  	return 0;
>>  }
>> diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
>> index 1ef0164..3a87bfc 100644
>> --- a/drivers/misc/cxl/pci.c
>> +++ b/drivers/misc/cxl/pci.c
>> @@ -789,7 +789,7 @@ int cxl_reset(struct cxl *adapter)
>>  	/* pcie_warm_reset requests a fundamental pci reset which includes a
>>  	 * PERST assert/deassert.  PERST triggers a loading of the image
>>  	 * if "user" or "factory" is selected in sysfs */
>> -	if ((rc = pci_set_pcie_reset_state(dev, pcie_warm_reset))) {
>> +	if ((rc = pci_set_pcie_reset_state(dev, pcie_warm_reset, 0))) {
>>  		dev_err(&dev->dev, "cxl: pcie_warm_reset failed\n");
>>  		return rc;
>>  	}
>> diff --git a/drivers/misc/genwqe/card_base.c b/drivers/misc/genwqe/card_base.c
>> index 4cf8f82..4871f69 100644
>> --- a/drivers/misc/genwqe/card_base.c
>> +++ b/drivers/misc/genwqe/card_base.c
>> @@ -782,17 +782,22 @@ static int genwqe_pci_fundamental_reset(struct pci_dev *pci_dev)
>>  {
>>  	int rc;
>>  
>> +	/* Probe if the device can take the reset */
>> +	rc = pci_set_pcie_reset_state(pci_dev, pcie_warm_reset, 1);
>> +	if (rc)
>> +		return rc;
>> +
>>  	/*
>>  	 * lock pci config space access from userspace,
>>  	 * save state and issue PCIe fundamental reset
>>  	 */
>>  	pci_cfg_access_lock(pci_dev);
>>  	pci_save_state(pci_dev);
>> -	rc = pci_set_pcie_reset_state(pci_dev, pcie_warm_reset);
>> +	rc = pci_set_pcie_reset_state(pci_dev, pcie_warm_reset, 0);
>>  	if (!rc) {
>>  		/* keep PCIe reset asserted for 250ms */
>>  		msleep(250);
>> -		pci_set_pcie_reset_state(pci_dev, pcie_deassert_reset);
>> +		pci_set_pcie_reset_state(pci_dev, pcie_deassert_reset, 0);
>>  		/* Wait for 2s to reload flash and train the link */
>>  		msleep(2000);
>>  	}
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 81f06e8..8581a5f 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -1558,28 +1558,31 @@ EXPORT_SYMBOL(pci_disable_device);
>>   * pcibios_set_pcie_reset_state - set reset state for device dev
>>   * @dev: the PCIe device reset
>>   * @state: Reset state to enter into
>> - *
>> + * @probe: Check if the device can take the reset
>>   *
>>   * Sets the PCIe reset state for the device. This is the default
>>   * implementation. Architecture implementations can override this.
>>   */
>>  int __weak pcibios_set_pcie_reset_state(struct pci_dev *dev,
>> -					enum pcie_reset_state state)
>> +					enum pcie_reset_state state,
>> +					int probe)
>>  {
>> -	return -EINVAL;
>> +	return -ENOTTY;
>>  }
>>  
>>  /**
>>   * pci_set_pcie_reset_state - set reset state for device dev
>>   * @dev: the PCIe device reset
>>   * @state: Reset state to enter into
>> - *
>> + * @probe: Check if the device can take the reset
>>   *
>>   * Sets the PCI reset state for the device.
>>   */
>> -int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state)
>> +int pci_set_pcie_reset_state(struct pci_dev *dev,
>> +			     enum pcie_reset_state state,
>> +			     int probe)
>>  {
>> -	return pcibios_set_pcie_reset_state(dev, state);
>> +	return pcibios_set_pcie_reset_state(dev, state, probe);
>>  }
>>  EXPORT_SYMBOL_GPL(pci_set_pcie_reset_state);
>>  
>> diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
>> index 9219953..89026f4 100644
>> --- a/drivers/scsi/ipr.c
>> +++ b/drivers/scsi/ipr.c
>> @@ -8317,7 +8317,8 @@ static int ipr_reset_start_bist(struct ipr_cmnd *ipr_cmd)
>>  static int ipr_reset_slot_reset_done(struct ipr_cmnd *ipr_cmd)
>>  {
>>  	ENTER;
>> -	pci_set_pcie_reset_state(ipr_cmd->ioa_cfg->pdev, pcie_deassert_reset);
>> +	pci_set_pcie_reset_state(ipr_cmd->ioa_cfg->pdev,
>> +				 pcie_deassert_reset, 0);
>>  	ipr_cmd->job_step = ipr_reset_bist_done;
>>  	ipr_reset_start_timer(ipr_cmd, IPR_WAIT_FOR_BIST_TIMEOUT);
>>  	LEAVE;
>> @@ -8339,7 +8340,7 @@ static int ipr_reset_slot_reset(struct ipr_cmnd *ipr_cmd)
>>  	struct pci_dev *pdev = ioa_cfg->pdev;
>>  
>>  	ENTER;
>> -	pci_set_pcie_reset_state(pdev, pcie_warm_reset);
>> +	pci_set_pcie_reset_state(pdev, pcie_warm_reset, 0);
>>  	ipr_cmd->job_step = ipr_reset_slot_reset_done;
>>  	ipr_reset_start_timer(ipr_cmd, IPR_PCI_RESET_TIMEOUT);
>>  	LEAVE;
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 4e1f17d..052ac63 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -960,7 +960,8 @@ extern unsigned int pcibios_max_latency;
>>  void pci_set_master(struct pci_dev *dev);
>>  void pci_clear_master(struct pci_dev *dev);
>>  
>> -int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state);
>> +int pci_set_pcie_reset_state(struct pci_dev *dev,
>> +			     enum pcie_reset_state state, int probe);
>>  int pci_set_cacheline_size(struct pci_dev *dev);
>>  #define HAVE_PCI_SET_MWI
>>  int __must_check pci_set_mwi(struct pci_dev *dev);
>> @@ -1648,7 +1649,7 @@ extern unsigned long pci_hotplug_mem_size;
>>  void pcibios_disable_device(struct pci_dev *dev);
>>  void pcibios_set_master(struct pci_dev *dev);
>>  int pcibios_set_pcie_reset_state(struct pci_dev *dev,
>> -				 enum pcie_reset_state state);
>> +				 enum pcie_reset_state state, int probe);
>>  int pcibios_add_device(struct pci_dev *dev);
>>  void pcibios_release_device(struct pci_dev *dev);
>>  void pcibios_penalize_isa_irq(int irq, int active);
>
>
>