[PATCH v3 0/3] ata: Fixes related to edge trigger latch for the ahci_xgene_driver.

[PATCH v3 0/3] ata: Fixes related to edge trigger latch for the ahci_xgene_driver.

[suman Tripathi]

From: Suman Tripathi <stripathi@apm.com>

This patch set implements a workaround for an errate in the APM
X-Gene SATA host controller with edge interrupt. The HOST_IRQ_STAT
misses the edge interrupt from the PORT_IRQ_STAT when clearing the
HOST_IRQ_STAT and reporting the PORT_IRQ_STAT happens in same clock
cycle. It also implements the capability to override generic interrupt
handler.

v1 change:
* Implement the capability for LDD to override interrupt handler.

* ahci_xgene driver implements the edge trigger interrupt handler.

v2 change:
* Remove the AHCI_HFLAG_EDGE_IRQ frim libahci.

v3 change:
* Reorder the patch sequence

Signed-off-by: Suman Tripathi <stripathi@apm.com>

Suman Tripathi (3):
  libahci: Implement the capability to override the generic ahci
    interrupt     handler.
  libahci: ata: Remove the AHCI_HFLAG_EDGE_IRQ support from libahci.
  ahci_xgene: Implement the workaround to fix the missing of edge
    interrupt for HOST_IRQ_STAT.

 drivers/ata/ahci.h       |    5 ++-
 drivers/ata/ahci_xgene.c |   85 +++++++++++++++++++++++++++++++++++++++++++++-
 drivers/ata/libahci.c    |   66 +++++++++++-------------------------
 3 files changed, 107 insertions(+), 49 deletions(-)

[PATCH v3 1/3] libahci: Implement the capability to override the generic ahci interrupt handler.

[suman Tripathi]

From: Suman Tripathi <stripathi@apm.com>

This patch implements the capability to override the generic
ahci interrupt handler so that the LDD drivers can implement
there own custom interrupt handler routines.

Signed-off-by: Suman Tripathi <stripathi@apm.com>
---
 drivers/ata/ahci.h    |    2 ++
 drivers/ata/libahci.c |   32 +++++++++++++++++++++++---------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index a4faa43..3d883ee 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -360,6 +360,7 @@ struct ahci_host_priv {
 	 * be overridden anytime before the host is activated.
 	 */
 	void			(*start_engine)(struct ata_port *ap);
+	irqreturn_t 		(*ahci_irq_intr)(int irq, void *dev_instance);
 };

 #ifdef CONFIG_PCI_MSI
@@ -423,6 +424,7 @@ int ahci_reset_em(struct ata_host *host);
 void ahci_print_info(struct ata_host *host, const char *scc_s);
 int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht);
 void ahci_error_handler(struct ata_port *ap);
+u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked);

 static inline void __iomem *__ahci_port_base(struct ata_host *host,
 					     unsigned int port_no)
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index eda3cf2..5d3035a 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1816,7 +1816,7 @@ static irqreturn_t ahci_multi_irqs_intr_hard(int irq, void *dev_instance)
 	return IRQ_HANDLED;
 }

-static u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)
+u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)
 {
 	unsigned int i, handled = 0;

@@ -1842,6 +1842,7 @@ static u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)

 	return handled;
 }
+EXPORT_SYMBOL_GPL(ahci_handle_port_intr);

 static irqreturn_t ahci_single_edge_irq_intr(int irq, void *dev_instance)
 {
@@ -2504,15 +2505,28 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
 	struct ahci_host_priv *hpriv = host->private_data;
 	int irq = hpriv->irq;
 	int rc;
+	irqreturn_t (*ahci_irq_handler)(int irq, void *dev_instance);

-	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX))
-		rc = ahci_host_activate_multi_irqs(host, sht);
-	else if (hpriv->flags & AHCI_HFLAG_EDGE_IRQ)
-		rc = ata_host_activate(host, irq, ahci_single_edge_irq_intr,
-				       IRQF_SHARED, sht);
-	else
-		rc = ata_host_activate(host, irq, ahci_single_level_irq_intr,
-				       IRQF_SHARED, sht);
+	ahci_irq_handler = hpriv->ahci_irq_intr;
+
+	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX)) {
+		if (!ahci_irq_handler)
+			rc = ahci_host_activate_multi_irqs(host, sht);
+		else
+			dev_warn(host->dev, "both AHCI_HFLAG_MULTI_MSI flag set \
+				 and custom irq handler implemented\n");
+
+	} else {
+		if (!ahci_irq_handler) {
+			ahci_irq_handler = (hpriv->flags & AHCI_HFLAG_EDGE_IRQ ?
+			 		    ahci_single_edge_irq_intr :
+					    ahci_single_level_irq_intr);
+		}
+	}
+
+	rc = ata_host_activate(host, irq, ahci_irq_handler,
+			       IRQF_SHARED, sht);
+
 	return rc;
 }
 EXPORT_SYMBOL_GPL(ahci_host_activate);
--
1.7.1

Re: [PATCH v3 1/3] libahci: Implement the capability to override the generic ahci interrupt handler.

[Sergei Shtylyov]

Hello.

On 02/05/2016 12:20 AM, suman Tripathi wrote:

> From: Suman Tripathi <stripathi@apm.com>
>
> This patch implements the capability to override the generic
> ahci interrupt handler so that the LDD drivers can implement

    AHCI.

> there own custom interrupt handler routines.

    s/there/their/.

> Signed-off-by: Suman Tripathi <stripathi@apm.com>
> ---
>   drivers/ata/ahci.h    |    2 ++
>   drivers/ata/libahci.c |   32 +++++++++++++++++++++++---------
>   2 files changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
> index a4faa43..3d883ee 100644
> --- a/drivers/ata/ahci.h
> +++ b/drivers/ata/ahci.h
> @@ -360,6 +360,7 @@ struct ahci_host_priv {
>   	 * be overridden anytime before the host is activated.
>   	 */
>   	void			(*start_engine)(struct ata_port *ap);
> +	irqreturn_t 		(*ahci_irq_intr)(int irq, void *dev_instance);

    The 'ahci_irq_intr' name is somewhat tautological.


[...]
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index eda3cf2..5d3035a 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
[...]
> @@ -2504,15 +2505,28 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
>   	struct ahci_host_priv *hpriv = host->private_data;
>   	int irq = hpriv->irq;
>   	int rc;
> +	irqreturn_t (*ahci_irq_handler)(int irq, void *dev_instance);
>
> -	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX))
> -		rc = ahci_host_activate_multi_irqs(host, sht);
> -	else if (hpriv->flags & AHCI_HFLAG_EDGE_IRQ)
> -		rc = ata_host_activate(host, irq, ahci_single_edge_irq_intr,
> -				       IRQF_SHARED, sht);
> -	else
> -		rc = ata_host_activate(host, irq, ahci_single_level_irq_intr,
> -				       IRQF_SHARED, sht);
> +	ahci_irq_handler = hpriv->ahci_irq_intr;
> +
> +	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX)) {
> +		if (!ahci_irq_handler)
> +			rc = ahci_host_activate_multi_irqs(host, sht);
> +		else
> +			dev_warn(host->dev, "both AHCI_HFLAG_MULTI_MSI flag set \
> +				 and custom irq handler implemented\n");
> +
> +	} else {
> +		if (!ahci_irq_handler) {

    Why not *else* *if* on a single line?

[...]

MBR, Sergei

Re: [PATCH v3 1/3] libahci: Implement the capability to override the generic ahci interrupt handler.

[Tejun Heo]

Hello,

On Fri, Feb 05, 2016 at 02:50:24AM +0530, suman Tripathi wrote:
...
> @@ -2504,15 +2505,28 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
>  	struct ahci_host_priv *hpriv = host->private_data;
>  	int irq = hpriv->irq;
>  	int rc;
> +	irqreturn_t (*ahci_irq_handler)(int irq, void *dev_instance);
> 
> +	ahci_irq_handler = hpriv->ahci_irq_intr;
> +
> +	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX)) {
> +		if (!ahci_irq_handler)
> +			rc = ahci_host_activate_multi_irqs(host, sht);
> +		else
> +			dev_warn(host->dev, "both AHCI_HFLAG_MULTI_MSI flag set \
> +				 and custom irq handler implemented\n");
> +
> +	} else {
> +		if (!ahci_irq_handler) {
> +			ahci_irq_handler = (hpriv->flags & AHCI_HFLAG_EDGE_IRQ ?
> +			 		    ahci_single_edge_irq_intr :
> +					    ahci_single_level_irq_intr);
> +		}
> +	}

I wrote this before but can't we do this in save_initial_config the
same way ->start_engine override is handled?

-- 
tejun

Re: [PATCH v3 1/3] libahci: Implement the capability to override the generic ahci interrupt handler.

[Suman Tripathi]

On Fri, Feb 5, 2016 at 8:41 AM, Tejun Heo <tj@kernel.org> wrote:
> Hello,
>
> On Fri, Feb 05, 2016 at 02:50:24AM +0530, suman Tripathi wrote:
> ...
>> @@ -2504,15 +2505,28 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
>>       struct ahci_host_priv *hpriv = host->private_data;
>>       int irq = hpriv->irq;
>>       int rc;
>> +     irqreturn_t (*ahci_irq_handler)(int irq, void *dev_instance);
>>
>> +     ahci_irq_handler = hpriv->ahci_irq_intr;
>> +
>> +     if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX)) {
>> +             if (!ahci_irq_handler)
>> +                     rc = ahci_host_activate_multi_irqs(host, sht);
>> +             else
>> +                     dev_warn(host->dev, "both AHCI_HFLAG_MULTI_MSI flag set \
>> +                              and custom irq handler implemented\n");
>> +
>> +     } else {
>> +             if (!ahci_irq_handler) {
>> +                     ahci_irq_handler = (hpriv->flags & AHCI_HFLAG_EDGE_IRQ ?
>> +                                         ahci_single_edge_irq_intr :
>> +                                         ahci_single_level_irq_intr);
>> +             }
>> +     }
>
> I wrote this before but can't we do this in save_initial_config the
> same way ->start_engine override is handled?

Sorry missed that out.
>
> --
> tejun



-- 
Thanks,
with regards,
Suman Tripathi

[PATCH v3 2/3] libahci: ata: Remove the AHCI_HFLAG_EDGE_IRQ support from libahci.

[suman Tripathi]

From: Suman Tripathi <stripathi-qTEPVZfXA3Y@public.gmane.org>

This patch removes the AHCI_HFLAG_EDGE_IRQ support from libahci.
The flexibility to override the irq handlers in the LLD's are
already present, so controller's implementing a EDGE triger latch
can implement their own interrupt handler inside the driver.

Signed-off-by: Suman Tripathi <stripathi-qTEPVZfXA3Y@public.gmane.org>
---
 drivers/ata/ahci.h       |    3 +--
 drivers/ata/ahci_xgene.c |   40 +++++++++++++++++++++++++++++++++++++++-
 drivers/ata/libahci.c    |   44 ++------------------------------------------
 3 files changed, 42 insertions(+), 45 deletions(-)

diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 3d883ee..284ce3a 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -240,8 +240,7 @@ enum {
 						        error-handling stage) */
 	AHCI_HFLAG_NO_DEVSLP		= (1 << 17), /* no device sleep */
 	AHCI_HFLAG_NO_FBS		= (1 << 18), /* no FBS */
-	AHCI_HFLAG_EDGE_IRQ		= (1 << 19), /* HOST_IRQ_STAT behaves as
-							Edge Triggered */
+
 #ifdef CONFIG_PCI_MSI
 	AHCI_HFLAG_MULTI_MSI		= (1 << 20), /* multiple PCI MSIs */
 	AHCI_HFLAG_MULTI_MSIX		= (1 << 21), /* per-port MSI-X */
diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
index e2c6d9e..a56ceeb 100644
--- a/drivers/ata/ahci_xgene.c
+++ b/drivers/ata/ahci_xgene.c
@@ -548,6 +548,43 @@ softreset_retry:
 	return rc;
 }

+static irqreturn_t xgene_ahci_irq_intr(int irq, void *dev_instance)
+{
+	struct ata_host *host = dev_instance;
+	struct ahci_host_priv *hpriv;
+	unsigned int rc = 0;
+	void __iomem *mmio;
+	u32 irq_stat, irq_masked;
+
+	VPRINTK("ENTER\n");
+
+	hpriv = host->private_data;
+	mmio = hpriv->mmio;
+
+	/* sigh.  0xffffffff is a valid return from h/w */
+	irq_stat = readl(mmio + HOST_IRQ_STAT);
+	if (!irq_stat)
+		return IRQ_NONE;
+
+	irq_masked = irq_stat & hpriv->port_map;
+
+	spin_lock(&host->lock);
+
+	/*
+	 * HOST_IRQ_STAT behaves as edge triggered latch meaning that
+	 * it should be cleared before all the port events are cleared.
+	 */
+	writel(irq_stat, mmio + HOST_IRQ_STAT);
+
+	rc = ahci_handle_port_intr(host, irq_masked);
+
+	spin_unlock(&host->lock);
+
+	VPRINTK("EXIT\n");
+
+	return IRQ_RETVAL(rc);
+}
+
 static struct ata_port_operations xgene_ahci_v1_ops = {
 	.inherits = &ahci_ops,
 	.host_stop = xgene_ahci_host_stop,
@@ -779,7 +816,8 @@ skip_clk_phy:
 		hpriv->flags = AHCI_HFLAG_NO_NCQ;
 		break;
 	case XGENE_AHCI_V2:
-		hpriv->flags |= AHCI_HFLAG_YES_FBS | AHCI_HFLAG_EDGE_IRQ;
+		hpriv->flags |= AHCI_HFLAG_YES_FBS;
+		hpriv->ahci_irq_intr = xgene_ahci_irq_intr;
 		break;
 	default:
 		break;
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 5d3035a..424d2b3 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1844,43 +1844,6 @@ u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)
 }
 EXPORT_SYMBOL_GPL(ahci_handle_port_intr);

-static irqreturn_t ahci_single_edge_irq_intr(int irq, void *dev_instance)
-{
-	struct ata_host *host = dev_instance;
-	struct ahci_host_priv *hpriv;
-	unsigned int rc = 0;
-	void __iomem *mmio;
-	u32 irq_stat, irq_masked;
-
-	VPRINTK("ENTER\n");
-
-	hpriv = host->private_data;
-	mmio = hpriv->mmio;
-
-	/* sigh.  0xffffffff is a valid return from h/w */
-	irq_stat = readl(mmio + HOST_IRQ_STAT);
-	if (!irq_stat)
-		return IRQ_NONE;
-
-	irq_masked = irq_stat & hpriv->port_map;
-
-	spin_lock(&host->lock);
-
-	/*
-	 * HOST_IRQ_STAT behaves as edge triggered latch meaning that
-	 * it should be cleared before all the port events are cleared.
-	 */
-	writel(irq_stat, mmio + HOST_IRQ_STAT);
-
-	rc = ahci_handle_port_intr(host, irq_masked);
-
-	spin_unlock(&host->lock);
-
-	VPRINTK("EXIT\n");
-
-	return IRQ_RETVAL(rc);
-}
-
 static irqreturn_t ahci_single_level_irq_intr(int irq, void *dev_instance)
 {
 	struct ata_host *host = dev_instance;
@@ -2517,11 +2480,8 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
 				 and custom irq handler implemented\n");

 	} else {
-		if (!ahci_irq_handler) {
-			ahci_irq_handler = (hpriv->flags & AHCI_HFLAG_EDGE_IRQ ?
-			 		    ahci_single_edge_irq_intr :
-					    ahci_single_level_irq_intr);
-		}
+		if (!ahci_irq_handler)
+			ahci_irq_handler = ahci_single_level_irq_intr;
 	}

 	rc = ata_host_activate(host, irq, ahci_irq_handler,
--
1.7.1

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[PATCH v3 3/3] ahci_xgene: Implement the workaround to fix the missing of edge interrupt for HOST_IRQ_STAT.

[suman Tripathi]

From: Suman Tripathi <stripathi@apm.com>

Due to H/W errata, the HOST_IRQ_STAT register misses the edge interrupt
when clearing the HOST_IRQ_STAT register and hardware reporting the
PORT_IRQ_STAT register at the same clock cycle.

Signed-off-by: Suman Tripathi <stripathi@apm.com>
---
 drivers/ata/ahci_xgene.c |   47 +++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 46 insertions(+), 1 deletions(-)

diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
index a56ceeb..6270bad 100644
--- a/drivers/ata/ahci_xgene.c
+++ b/drivers/ata/ahci_xgene.c
@@ -548,6 +548,51 @@ softreset_retry:
 	return rc;
 }

+/**
+ * xgene_ahci_handle_broken_edge_irq - Handle the broken irq.
+ * @ata_host: Host that recieved the irq
+ * @irq_masked: HOST_IRQ_STAT value
+ *
+ * For hardware with broken edge trigger latch
+ * the HOST_IRQ_STAT register misses the edge interrupt
+ * when clearing of HOST_IRQ_STAT register and hardware
+ * reporting the PORT_IRQ_STAT register at the
+ * same clock cycle.
+ * As such, the algorithm below outlines the workaround.
+ *
+ * 1. Read HOST_IRQ_STAT register and save the state.
+ * 2. Clear the HOST_IRQ_STAT register.
+ * 3. Read back the HOST_IRQ_STAT register.
+ * 4. If HOST_IRQ_STAT register equals to zero, then
+ *    traverse the rest of port's PORT_IRQ_STAT register
+ *    to check if an interrupt is triggered at that point else
+ *    go to step 6.
+ * 5. If PORT_IRQ_STAT register of rest ports is not equal to zero
+ *    then update the state of HOST_IRQ_STAT saved in step 1.
+ * 6. Handle port interrupts.
+ * 7. Exit
+ */
+static int xgene_ahci_handle_broken_edge_irq(struct ata_host *host,
+					     u32 irq_masked)
+{
+	struct ahci_host_priv *hpriv = host->private_data;
+	void __iomem *port_mmio;
+	int i;
+
+	if (!readl(hpriv->mmio + HOST_IRQ_STAT)) {
+		for (i = 0; i < host->n_ports; i++) {
+			if (irq_masked & (1 << i))
+				continue;
+
+			port_mmio = ahci_port_base(host->ports[i]);
+			if (readl(port_mmio + PORT_IRQ_STAT))
+				irq_masked |= (1 << i);
+		}
+	}
+
+	return ahci_handle_port_intr(host, irq_masked);
+}
+
 static irqreturn_t xgene_ahci_irq_intr(int irq, void *dev_instance)
 {
 	struct ata_host *host = dev_instance;
@@ -576,7 +621,7 @@ static irqreturn_t xgene_ahci_irq_intr(int irq, void *dev_instance)
 	 */
 	writel(irq_stat, mmio + HOST_IRQ_STAT);

-	rc = ahci_handle_port_intr(host, irq_masked);
+	rc = xgene_ahci_handle_broken_edge_irq(host, irq_masked);

 	spin_unlock(&host->lock);

--
1.7.1