linux-kernel - Re: Hang during boot, bisected to commit 96d60303fd

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Date:	Mon, 07 Jun 2010 11:22:37 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Robert Hancock <hancockrwd@...il.com>
CC:	Marc Dionne <marc.c.dionne@...il.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-ide@...r.kernel.org, garzik@...hat.com
Subject: Re: Hang during boot, bisected to commit 96d60303fd

Hello,

On 06/07/2010 06:34 AM, Robert Hancock wrote:
> I'm thinking that the hardreset and device classification makes more
> sense as a place to do this anyways, since that's the point where we
> really know if there's a device connected or not.. Tejun, any
> thoughts?

Heh, of course it doesn't work.  Device presence can't be reliably
determined by sampling status once like that.  We don't have all the
crap in libata-eh for nothing.  :-)

Marc, can you please try the following patch?

Thanks.

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 1984a6e..261f86d 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -541,29 +541,11 @@ static int ahci_scr_write(struct ata_link *link, unsigned int sc_reg, u32 val)
 	return -EINVAL;
 }

-static int ahci_is_device_present(void __iomem *port_mmio)
-{
-	u8 status = readl(port_mmio + PORT_TFDATA) & 0xff;
-
-	/* Make sure PxTFD.STS.BSY and PxTFD.STS.DRQ are 0 */
-	if (status & (ATA_BUSY | ATA_DRQ))
-		return 0;
-
-	/* Make sure PxSSTS.DET is 3h */
-	status = readl(port_mmio + PORT_SCR_STAT) & 0xf;
-	if (status != 3)
-		return 0;
-	return 1;
-}
-
 void ahci_start_engine(struct ata_port *ap)
 {
 	void __iomem *port_mmio = ahci_port_base(ap);
 	u32 tmp;

-	if (!ahci_is_device_present(port_mmio))
-		return;
-
 	/* start DMA */
 	tmp = readl(port_mmio + PORT_CMD);
 	tmp |= PORT_CMD_START;
@@ -1892,6 +1874,9 @@ static void ahci_error_handler(struct ata_port *ap)
 	}

 	sata_pmp_error_handler(ap);
+
+	if (!ata_dev_enabled(ap->link.device))
+		ahci_stop_engine(ap);
 }

 static void ahci_post_internal_cmd(struct ata_queued_cmd *qc)

-- 
tejun
--
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