linux-kernel - Re: [PATCH] AHCI: Add generic MSI-X interrupt support to SATA PCI driver

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Date:	Mon, 10 Nov 2014 22:51:44 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Robert Richter <rric@...nel.org>, Tejun Heo <tj@...nel.org>
CC:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-ide@...r.kernel.org, Sunil Goutham <sgoutham@...ium.com>,
	Robert Richter <rrichter@...ium.com>
Subject: Re: [PATCH] AHCI: Add generic MSI-X interrupt support to SATA PCI
 driver

On 2014/11/10 13:30, Robert Richter wrote:
> From: Sunil Goutham <sgoutham@...ium.com>
> 
> This patch adds generic support for MSI-X interrupts to the SATA PCI
> driver. Only single interrupt support is implemented. Thus, per-port
> interrupts can not yet be enabled.
> 
> The driver now checks the device for the existence of MSI-X and tries
> to enable the interrupt. Otherwise, if a device is not MSI-X capable,
> the initialization is skipped and MSI or intx interrupts are
> configured.
> 
> This patch also enables AHCI for Cavium Thunder SoCs that uses MSI-X.
> 
> Signed-off-by: Sunil Goutham <sgoutham@...ium.com>
> Signed-off-by: Robert Richter <rrichter@...ium.com>
> ---
>  arch/arm64/Kconfig |  1 +
>  drivers/ata/ahci.c | 40 +++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index ac9afde76dea..55970474d3ae 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -145,6 +145,7 @@ config ARCH_THUNDER
>  	bool "Cavium Inc. Thunder SoC Family"
>  	help
>  	  This enables support for Cavium's Thunder Family of SoCs.
> +	select SATA_AHCI
>  
>  config ARCH_VEXPRESS
>  	bool "ARMv8 software model (Versatile Express)"
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index 5f039f191067..8e43ccb72c95 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -52,6 +52,7 @@
>  
>  enum {
>  	AHCI_PCI_BAR_STA2X11	= 0,
> +	AHCI_PCI_BAR_CAVIUM	= 0,
>  	AHCI_PCI_BAR_ENMOTUS	= 2,
>  	AHCI_PCI_BAR_STANDARD	= 5,
>  };
> @@ -483,6 +484,9 @@ static const struct pci_device_id ahci_pci_tbl[] = {
>  	/* Enmotus */
>  	{ PCI_DEVICE(0x1c44, 0x8000), board_ahci },
>  
> +	/* Cavium */
> +	{ PCI_DEVICE(0x177d, 0xa01c), .driver_data = board_ahci },
> +
>  	/* Generic, PCI class code for AHCI */
>  	{ PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>  	  PCI_CLASS_STORAGE_SATA_AHCI, 0xffffff, board_ahci },
> @@ -1188,11 +1192,43 @@ static inline void ahci_gtf_filter_workaround(struct ata_host *host)
>  {}
>  #endif
>  
> +static int ahci_init_msix(struct pci_dev *pdev, unsigned int n_ports,
> +			  struct ahci_host_priv *hpriv)
> +{
> +	int rc, nvec;
> +	struct msix_entry entry = {};
> +
> +	/* check if msix is supported */
> +	nvec = pci_msix_vec_count(pdev);
> +	if (nvec <= 0)
> +		return 0;
> +
> +	/* per-port msix interrupts are not supported */
> +	if (n_ports > 1 && nvec >= n_ports)
> +		return -ENOSYS;
> +
> +	/* only enable the first entry (entry.entry = 0) */
> +	rc = pci_enable_msix_exact(pdev, &entry, 1);
> +	if (rc < 0)
> +		return rc;
> +
> +	pdev->irq = entry.vector;
Hi Robert,
	You can't overwrite pci_dev->irq for MSI-X, it's no way to
recover original irq for INTx after unbinding ahci driver. Instead,
you may access msi_desc->irq when requesting irq.
Regards!
Gerry
> +
> +	return 1;
> +}
> +
>  static int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
>  				struct ahci_host_priv *hpriv)
>  {
>  	int rc, nvec;
>  
> +	nvec = ahci_init_msix(pdev, n_ports, hpriv);
> +	if (nvec > 0)
> +		return nvec;
> +
> +	if (nvec && nvec != -ENOSYS)
> +		dev_err(&pdev->dev, "failed to enable MSI-X: %d", nvec);
> +
>  	if (hpriv->flags & AHCI_HFLAG_NO_MSI)
>  		goto intx;
>  
> @@ -1271,11 +1307,13 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  		dev_info(&pdev->dev,
>  			 "PDC42819 can only drive SATA devices with this driver\n");
>  
> -	/* Both Connext and Enmotus devices use non-standard BARs */
> +	/* Some devices use non-standard BARs */
>  	if (pdev->vendor == PCI_VENDOR_ID_STMICRO && pdev->device == 0xCC06)
>  		ahci_pci_bar = AHCI_PCI_BAR_STA2X11;
>  	else if (pdev->vendor == 0x1c44 && pdev->device == 0x8000)
>  		ahci_pci_bar = AHCI_PCI_BAR_ENMOTUS;
> +	else if (pdev->vendor == 0x177d && pdev->device == 0xa01c)
> +		ahci_pci_bar = AHCI_PCI_BAR_CAVIUM;
>  
>  	/*
>  	 * The JMicron chip 361/363 contains one SATA controller and one
> 
--
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