Re: [PATCH 1/2] ipr: add test for MSI interrupt support

[Brian King <brking@linux.vnet.ibm.com>]

Acked-by: Brian King <brking@linux.vnet.ibm.com>

Wayne Boyer wrote:
> The return value from pci_enable_msi() can not always be trusted.  This patch
> adds code to generate an interrupt after MSI has been enabled and tests
> whether or not we can receive and process it.  If the tests fails, then fall
> back to LSI.
> 
> Signed-off-by: Wayne Boyer <wayneb@linux.vnet.ibm.com>
> ---
> 
>  drivers/scsi/ipr.c |  108 +++++++++++++++++++++++++++++++++++++++++++++++++----
>  drivers/scsi/ipr.h |    6 +-
>  2 files changed, 105 insertions(+), 9 deletions(-)
> 
> Index: b/drivers/scsi/ipr.c
> ===================================================================
> --- a/drivers/scsi/ipr.c	2009-06-03 16:04:14.000000000 -0700
> +++ b/drivers/scsi/ipr.c	2009-06-15 16:36:36.000000000 -0700
> @@ -7366,6 +7366,7 @@
>  	INIT_LIST_HEAD(&ioa_cfg->used_res_q);
>  	INIT_WORK(&ioa_cfg->work_q, ipr_worker_thread);
>  	init_waitqueue_head(&ioa_cfg->reset_wait_q);
> +	init_waitqueue_head(&ioa_cfg->msi_wait_q);
>  	ioa_cfg->sdt_state = INACTIVE;
>  	if (ipr_enable_cache)
>  		ioa_cfg->cache_state = CACHE_ENABLED;
> @@ -7416,6 +7417,89 @@
>  }
> 
>  /**
> + * ipr_test_intr - Handle the interrupt generated in ipr_test_msi().
> + * @pdev:		PCI device struct
> + *
> + * Description: Simply set the msi_received flag to 1 indicating that
> + * Message Signaled Interrupts are supported.
> + *
> + * Return value:
> + * 	0 on success / non-zero on failure
> + **/
> +static irqreturn_t __devinit ipr_test_intr(int irq, void *devp)
> +{
> +	struct ipr_ioa_cfg *ioa_cfg = (struct ipr_ioa_cfg *)devp;
> +	unsigned long lock_flags = 0;
> +	irqreturn_t rc = IRQ_HANDLED;
> +
> +	spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
> +
> +	ioa_cfg->msi_received = 1;
> +	wake_up(&ioa_cfg->msi_wait_q);
> +
> +	spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
> +	return rc;
> +}
> +
> +/**
> + * ipr_test_msi - Test for Message Signaled Interrupt (MSI) support.
> + * @pdev:		PCI device struct
> + *
> + * Description: The return value from pci_enable_msi() can not always be
> + * trusted.  This routine sets up and initiates a test interrupt to determine
> + * if the interrupt is received via the ipr_test_intr() service routine.
> + * If the tests fails, the driver will fall back to LSI.
> + *
> + * Return value:
> + * 	0 on success / non-zero on failure
> + **/
> +static int __devinit ipr_test_msi(struct ipr_ioa_cfg *ioa_cfg,
> +				  struct pci_dev *pdev)
> +{
> +	int rc;
> +	volatile u32 int_reg;
> +	unsigned long lock_flags = 0;
> +
> +	ENTER;
> +
> +	spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
> +	init_waitqueue_head(&ioa_cfg->msi_wait_q);
> +	ioa_cfg->msi_received = 0;
> +	ipr_mask_and_clear_interrupts(ioa_cfg, ~IPR_PCII_IOA_TRANS_TO_OPER);
> +	writel(IPR_PCII_IO_DEBUG_ACKNOWLEDGE, ioa_cfg->regs.clr_interrupt_mask_reg);
> +	int_reg = readl(ioa_cfg->regs.sense_interrupt_mask_reg);
> +	spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
> +
> +	rc = request_irq(pdev->irq, ipr_test_intr, 0, IPR_NAME, ioa_cfg);
> +	if (rc) {
> +		dev_err(&pdev->dev, "Can not assign irq %d\n", pdev->irq);
> +		return rc;
> +	} else if (ipr_debug)
> +		dev_info(&pdev->dev, "IRQ assigned: %d\n", pdev->irq);
> +
> +	writel(IPR_PCII_IO_DEBUG_ACKNOWLEDGE, ioa_cfg->regs.sense_interrupt_reg);
> +	int_reg = readl(ioa_cfg->regs.sense_interrupt_reg);
> +	wait_event_timeout(ioa_cfg->msi_wait_q, ioa_cfg->msi_received, HZ);
> +	ipr_mask_and_clear_interrupts(ioa_cfg, ~IPR_PCII_IOA_TRANS_TO_OPER);
> +
> +	spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
> +	if (!ioa_cfg->msi_received) {
> +		/* MSI test failed */
> +		dev_info(&pdev->dev, "MSI test failed.  Falling back to LSI.\n");
> +		rc = -EOPNOTSUPP;
> +	} else if (ipr_debug)
> +		dev_info(&pdev->dev, "MSI test succeeded.\n");
> +
> +	spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
> +
> +	free_irq(pdev->irq, ioa_cfg);
> +
> +	LEAVE;
> +
> +	return rc;
> +}
> +
> +/**
>   * ipr_probe_ioa - Allocates memory and does first stage of initialization
>   * @pdev:		PCI device struct
>   * @dev_id:		PCI device id struct
> @@ -7440,11 +7524,6 @@
>  		goto out;
>  	}
> 
> -	if (!(rc = pci_enable_msi(pdev)))
> -		dev_info(&pdev->dev, "MSI enabled\n");
> -	else if (ipr_debug)
> -		dev_info(&pdev->dev, "Cannot enable MSI\n");
> -
>  	dev_info(&pdev->dev, "Found IOA with IRQ: %d\n", pdev->irq);
> 
>  	host = scsi_host_alloc(&driver_template, sizeof(*ioa_cfg));
> @@ -7518,6 +7597,18 @@
>  		goto cleanup_nomem;
>  	}
> 
> +	/* Enable MSI style interrupts if they are supported. */
> +	if (!(rc = pci_enable_msi(pdev))) {
> +		rc = ipr_test_msi(ioa_cfg, pdev);
> +		if (rc == -EOPNOTSUPP)
> +			pci_disable_msi(pdev);
> +		else if (rc)
> +			goto out_msi_disable;
> +		else
> +			dev_info(&pdev->dev, "MSI enabled with IRQ: %d\n", pdev->irq);
> +	} else if (ipr_debug)
> +		dev_info(&pdev->dev, "Cannot enable MSI.\n");
> +
>  	/* Save away PCI config space for use following IOA reset */
>  	rc = pci_save_state(pdev);
> 
> @@ -7555,7 +7646,9 @@
>  		ioa_cfg->ioa_unit_checked = 1;
> 
>  	ipr_mask_and_clear_interrupts(ioa_cfg, ~IPR_PCII_IOA_TRANS_TO_OPER);
> -	rc = request_irq(pdev->irq, ipr_isr, IRQF_SHARED, IPR_NAME, ioa_cfg);
> +	rc = request_irq(pdev->irq, ipr_isr,
> +			 ioa_cfg->msi_received ? 0 : IRQF_SHARED,
> +			 IPR_NAME, ioa_cfg);
> 
>  	if (rc) {
>  		dev_err(&pdev->dev, "Couldn't register IRQ %d! rc=%d\n",
> @@ -7582,12 +7675,13 @@
>  	ipr_free_mem(ioa_cfg);
>  cleanup_nomem:
>  	iounmap(ipr_regs);
> +out_msi_disable:
> +	pci_disable_msi(pdev);
>  out_release_regions:
>  	pci_release_regions(pdev);
>  out_scsi_host_put:
>  	scsi_host_put(host);
>  out_disable:
> -	pci_disable_msi(pdev);
>  	pci_disable_device(pdev);
>  	goto out;
>  }
> Index: b/drivers/scsi/ipr.h
> ===================================================================
> --- a/drivers/scsi/ipr.h	2009-06-03 16:04:15.000000000 -0700
> +++ b/drivers/scsi/ipr.h	2009-06-15 16:35:43.000000000 -0700
> @@ -37,8 +37,8 @@
>  /*
>   * Literals
>   */
> -#define IPR_DRIVER_VERSION "2.4.2"
> -#define IPR_DRIVER_DATE "(January 21, 2009)"
> +#define IPR_DRIVER_VERSION "2.4.3"
> +#define IPR_DRIVER_DATE "(June 10, 2009)"
> 
>  /*
>   * IPR_MAX_CMD_PER_LUN: This defines the maximum number of outstanding
> @@ -1094,6 +1094,7 @@
>  	u8 needs_hard_reset:1;
>  	u8 dual_raid:1;
>  	u8 needs_warm_reset:1;
> +	u8 msi_received:1;
> 
>  	u8 revid;
> 
> @@ -1179,6 +1180,7 @@
>  	struct work_struct work_q;
> 
>  	wait_queue_head_t reset_wait_q;
> +	wait_queue_head_t msi_wait_q;
> 
>  	struct ipr_dump *dump;
>  	enum ipr_sdt_state sdt_state;
> 
> --
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-- 
Brian King
Linux on Power Virtualization
IBM Linux Technology Center