Re: [PATCH/RFC] ahci: add support for VIA VT8251

[Bastiaan Jacques <b.jacques@planet.nl>]

On Wednesday 12 April 2006 21:25, Jeff Garzik wrote:
> > +	readl(port_mmio + PORT_CMD); /* flush */
> 
> ahci_poll_register() should take care of flush for you.

Done.

> > +		if ((rc = ahci_clo(ap))) {
> 
> Don't combine an assignment and an 'if' test in the same line.

Done.

> > +	/* VIA VT8251-specific fixup: CLO before reset */
> > +	if (pdev->device == 0x3349)
> > +		hpriv->flags |= AHCI_FLAG_RESET_NEEDS_CLO;
> 
> This is flawed because it doesn't check the PCI vendor ID.
> 
> In any case, the proper way to do this is:
> 
> 1) create board_ahci_via next to board_ahci
> 
> 2) duplicate entry #0 (board_ahci) of ahci_port_info[] as entry #1 
> (board_ahci_via).

The vendor patch already contained a similar entry which I used in this
revision. However, I modified it as follows:

a) Named it board_via_vt8251_ahci, as per Sergey Vlasov's suggestion. Future
   VIA chipsets won't necessarily require this workaround.
b) Removed ATA_FLAG_SRST from .host_flags as it appears to be deprecated (and
   soft/hardreset works anyway).
c) Left .pio_mask = 0x03, /* pio3-4 */ from vendor patch intact, as I didn't
   find anything in the AHCI specification that would require otherwise (and
   I assume VIA did this for a reason).

> 3) Add AHCI_FLAG_RESET_NEEDS_CLO to entry #1.
> 
> 4) test ap->flags & AHCI_FLAG_RESET_NEEDS_CLO
> 
> 5) when adding VIA PCI device to ahci_pci_tbl[], the final entry should 
> be 'board_ahci_via'

Done 1-5.


--- drivers/scsi/ahci.c.orig	2006-04-11 18:58:32.000000000 +0200
+++ drivers/scsi/ahci.c	2006-04-12 22:45:37.000000000 +0200
@@ -73,6 +73,7 @@ enum {
 	RX_FIS_D2H_REG		= 0x40,	/* offset of D2H Register FIS data */
 
 	board_ahci		= 0,
+	board_via_vt8251_ahci   = 1,
 
 	/* global controller registers */
 	HOST_CAP		= 0x00, /* host capabilities */
@@ -153,6 +154,9 @@ enum {
 
 	/* hpriv->flags bits */
 	AHCI_FLAG_MSI		= (1 << 0),
+
+	/* ap->flags bits */
+	AHCI_FLAG_RESET_NEEDS_CLO	= (1 << 24),
 };
 
 struct ahci_cmd_hdr {
@@ -256,6 +260,16 @@ static const struct ata_port_info ahci_p
 		.udma_mask	= 0x7f, /* udma0-6 ; FIXME */
 		.port_ops	= &ahci_ops,
 	},
+	/* board_via_vt8251_ahci */
+	{
+		.sht		= &ahci_sht,
+		.host_flags	= ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY |
+				  ATA_FLAG_MMIO | ATA_FLAG_PIO_DMA |
+				  AHCI_FLAG_RESET_NEEDS_CLO,
+		.pio_mask	= 0x03, /* pio3-4 */
+		.udma_mask	= 0x7f, /* udma0-6 ; FIXME */
+		.port_ops	= &ahci_ops,
+	},
 };
 
 static const struct pci_device_id ahci_pci_tbl[] = {
@@ -297,6 +311,8 @@ static const struct pci_device_id ahci_p
 	  board_ahci }, /* ATI SB600 non-raid */
 	{ PCI_VENDOR_ID_ATI, 0x4381, PCI_ANY_ID, PCI_ANY_ID, 0, 0,
 	  board_ahci }, /* ATI SB600 raid */
+	{ PCI_VENDOR_ID_VIA, 0x3349, PCI_ANY_ID, PCI_ANY_ID, 0, 0,
+	  board_via_vt8251_ahci }, /* VT8251 */
 	{ }	/* terminate list */
 };
 
@@ -535,9 +551,27 @@ static int ahci_poll_register(void __iom
 	return -1;
 }
 
-static int ahci_softreset(struct ata_port *ap, int verbose, unsigned int *class)
+static int ahci_clo(struct ata_port *ap)
 {
+	void __iomem *port_mmio = (void __iomem *) ap->ioaddr.cmd_addr;
 	struct ahci_host_priv *hpriv = ap->host_set->private_data;
+	u32 tmp;
+
+	if (!(hpriv->cap & HOST_CAP_CLO))
+		return -EOPNOTSUPP;
+
+	tmp = readl(port_mmio + PORT_CMD);
+	tmp |= PORT_CMD_CLO;
+	writel(tmp, port_mmio + PORT_CMD);
+
+	if (ahci_poll_register(port_mmio + PORT_CMD, PORT_CMD_CLO, 0x0, 1, 500))
+		return -EIO;
+
+	return 0;
+}
+
+static int ahci_softreset(struct ata_port *ap, int verbose, unsigned int *class)
+{
 	struct ahci_port_priv *pp = ap->private_data;
 	void __iomem *mmio = ap->host_set->mmio_base;
 	void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
@@ -565,23 +599,13 @@ static int ahci_softreset(struct ata_por
 	/* check BUSY/DRQ, perform Command List Override if necessary */
 	ahci_tf_read(ap, &tf);
 	if (tf.command & (ATA_BUSY | ATA_DRQ)) {
-		u32 tmp;
+		rc = ahci_clo(ap);
 
-		if (!(hpriv->cap & HOST_CAP_CLO)) {
-			rc = -EIO;
-			reason = "port busy but no CLO";
+		if (rc == -EOPNOTSUPP) {
+			reason = "port busy but CLO unavailable";
 			goto fail_restart;
-		}
-
-		tmp = readl(port_mmio + PORT_CMD);
-		tmp |= PORT_CMD_CLO;
-		writel(tmp, port_mmio + PORT_CMD);
-		readl(port_mmio + PORT_CMD); /* flush */
-
-		if (ahci_poll_register(port_mmio + PORT_CMD, PORT_CMD_CLO, 0x0,
-				       1, 500)) {
-			rc = -EIO;
-			reason = "CLO failed";
+		} else if (rc == -EIO) {
+			reason = "port busy but CLO failed";
 			goto fail_restart;
 		}
 	}
@@ -695,6 +719,12 @@ static void ahci_postreset(struct ata_po
 
 static int ahci_probe_reset(struct ata_port *ap, unsigned int *classes)
 {
+	if (ap->flags & AHCI_FLAG_RESET_NEEDS_CLO &&
+	    ata_busy_wait(ap, ATA_BUSY, 1000) & ATA_BUSY) {
+		/* ATA_BUSY hasn't cleared, so send a CLO */
+		ahci_clo(ap);
+	}
+
 	return ata_drive_probe_reset(ap, ata_std_probeinit,
 				     ahci_softreset, ahci_hardreset,
 				     ahci_postreset, classes);