Re: sata_mv query

[Mark Lord <kernel@teksavvy.com>]

[-- Attachment #1: Type: text/plain, Size: 1327 bytes --]

On 12-08-07 02:17 PM, Mark Lord wrote:
..
> Say, here's a thought:  We could get rid of (or relocate to upper layers)
> the busy-wait by having something similar get called from ata_qc_defer().
> 
> If you are feeling adventurous, here is a 100% untested patch to do just that.
> It looks correct to me, it compiles, but that's all I can say.

Whoops.. return codes were reversed.
Here's the corrected patch.

The attached copy is the better one to use -- my mailer mangles inline patches.

--- linux-3.4.4/drivers/ata/sata_mv.c	2012-06-22 14:37:50.000000000 -0400
+++ linux/drivers/ata/sata_mv.c	2012-08-07 14:14:43.554503157 -0400
@@ -1388,6 +1388,17 @@
 	}
 }

+static int mv_check_for_edma_empty_idle(struct ata_port *ap)
+{
+	void __iomem *port_mmio = mv_ap_base(ap);
+	const u32 empty_idle = (EDMA_STATUS_CACHE_EMPTY | EDMA_STATUS_IDLE);
+
+	u32 edma_stat = readl(port_mmio + EDMA_STATUS);
+	if ((edma_stat & empty_idle) == empty_idle)
+		return 0;
+	return ATA_DEFER_PORT;
+}
+
 static int mv_qc_defer(struct ata_queued_cmd *qc)
 {
 	struct ata_link *link = qc->dev->link;
@@ -1423,7 +1434,7 @@
 	 * If the port is completely idle, then allow the new qc.
 	 */
 	if (ap->nr_active_links == 0)
-		return 0;
+		return mv_check_for_edma_empty_idle(ap);

 	/*
 	 * The port is operating in host queuing mode (EDMA) with NCQ

[-- Attachment #2: xx_sata_mv_move_busywait.patch --]
[-- Type: text/x-patch, Size: 838 bytes --]

--- linux-3.4.4/drivers/ata/sata_mv.c	2012-06-22 14:37:50.000000000 -0400
+++ linux/drivers/ata/sata_mv.c	2012-08-07 14:14:43.554503157 -0400
@@ -1388,6 +1388,17 @@
 	}
 }
 
+static int mv_check_for_edma_empty_idle(struct ata_port *ap)
+{
+	void __iomem *port_mmio = mv_ap_base(ap);
+	const u32 empty_idle = (EDMA_STATUS_CACHE_EMPTY | EDMA_STATUS_IDLE);
+
+	u32 edma_stat = readl(port_mmio + EDMA_STATUS);
+	if ((edma_stat & empty_idle) == empty_idle)
+		return 0;
+	return ATA_DEFER_PORT;
+}
+
 static int mv_qc_defer(struct ata_queued_cmd *qc)
 {
 	struct ata_link *link = qc->dev->link;
@@ -1423,7 +1434,7 @@
 	 * If the port is completely idle, then allow the new qc.
 	 */
 	if (ap->nr_active_links == 0)
-		return 0;
+		return mv_check_for_edma_empty_idle(ap);
 
 	/*
 	 * The port is operating in host queuing mode (EDMA) with NCQ