Patchwork [v2,5/6] AHCI: Check MRSM bit when multiple MSIs enabled

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Submitter Alexander Gordeev
Date Sept. 5, 2013, 12:54 p.m.
Message ID <4bc31d6ccf3f84399b977fe8ed4fe77aadfa1c79.1378383792.git.agordeev@redhat.com>
Download mbox | patch
Permalink /patch/272884/
State Superseded
Headers show

Comments

Alexander Gordeev - Sept. 5, 2013, 12:54 p.m.
Do not trust the hardware and always check if MSI
Revert to Single Message mode was enforced. Fall
back to the single MSI mode in case it did. Not
doing so might screw up the interrupt handling.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
---
 drivers/ata/ahci.c |   16 ++++++++++++++++
 drivers/ata/ahci.h |    1 +
 2 files changed, 17 insertions(+), 0 deletions(-)
Tejun Heo - Sept. 5, 2013, 1:11 p.m.
On Thu, Sep 05, 2013 at 02:54:17PM +0200, Alexander Gordeev wrote:
> Do not trust the hardware and always check if MSI
> Revert to Single Message mode was enforced. Fall
> back to the single MSI mode in case it did. Not
> doing so might screw up the interrupt handling.
> 
> Signed-off-by: Alexander Gordeev <agordeev@redhat.com>

 Acked-by: Tejun Heo <tj@kernel.org>

The patch should probably be re-sequenced to the head of the series
and cc stable@vger.kernel.org.  Not checking MRSM is scary.

Thanks.
Sergei Shtylyov - Sept. 5, 2013, 2:32 p.m.
Hello.

On 09/05/2013 04:54 PM, Alexander Gordeev wrote:

> Do not trust the hardware and always check if MSI
> Revert to Single Message mode was enforced. Fall
> back to the single MSI mode in case it did. Not
> doing so might screw up the interrupt handling.

> Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
> ---
>   drivers/ata/ahci.c |   16 ++++++++++++++++
>   drivers/ata/ahci.h |    1 +
>   2 files changed, 17 insertions(+), 0 deletions(-)

> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index a6bb618..af5d535 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -1091,6 +1091,14 @@ static inline void ahci_gtf_filter_workaround(struct ata_host *host)
>   {}
>   #endif
>
> +static int ahci_get_mrsm(struct ahci_host_priv *hpriv)
> +{
> +	void __iomem *mmio = hpriv->mmio;
> +	u32 ctl = readl(mmio + HOST_CTL);
> +
> +	return (ctl & HOST_MRSM);

    Parens not needed here, in case you'll respin this once more.

WBR, Sergei

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Alexander Gordeev - Sept. 5, 2013, 3:25 p.m.
On Thu, Sep 05, 2013 at 09:11:49AM -0400, Tejun Heo wrote:
> On Thu, Sep 05, 2013 at 02:54:17PM +0200, Alexander Gordeev wrote:
> The patch should probably be re-sequenced to the head of the series
> and cc stable@vger.kernel.org.  Not checking MRSM is scary.

Will resend v3.

> Thanks.
> 
> -- 
> tejun

Patch

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index a6bb618..af5d535 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1091,6 +1091,14 @@  static inline void ahci_gtf_filter_workaround(struct ata_host *host)
 {}
 #endif
 
+static int ahci_get_mrsm(struct ahci_host_priv *hpriv)
+{
+	void __iomem *mmio = hpriv->mmio;
+	u32 ctl = readl(mmio + HOST_CTL);
+
+	return (ctl & HOST_MRSM);
+}
+
 int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
 			 struct ahci_host_priv *hpriv)
 {
@@ -1111,6 +1119,14 @@  int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
 		goto intx;
 	if (rc)
 		goto single_msi;
+	if (maxvec == 1)
+		return 1;
+
+	if (ahci_get_mrsm(hpriv)) {
+		pci_disable_msi(pdev);
+		printk(KERN_INFO "ahci: MRSM is on, fallback to single MSI\n");
+		goto single_msi;
+	}
 
 	return maxvec;
 
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 1145637..19bc846 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -91,6 +91,7 @@  enum {
 	/* HOST_CTL bits */
 	HOST_RESET		= (1 << 0),  /* reset controller; self-clear */
 	HOST_IRQ_EN		= (1 << 1),  /* global IRQ enable */
+	HOST_MRSM		= (1 << 2),  /* MSI Revert to Single Message */
 	HOST_AHCI_EN		= (1 << 31), /* AHCI enabled */
 
 	/* HOST_CAP bits */