[PATCH] pata_via: Cache and rewrite the device bit

[Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>]

Some VIA chipsets will reset the DEV bit after IEN changes on ctl. Our
optimised write path avoids doing this but we need to remove the
optimisation on these devices.

[Identified and some original patches proposed by Josehn Chan @ VIA but
discussion then all ground to a halt so given a test case I dug it back out]

Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx
Tested-by: Christoph Bisping (bug #13086)
---

 drivers/ata/pata_via.c |   74 +++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 67 insertions(+), 7 deletions(-)


diff --git a/drivers/ata/pata_via.c b/drivers/ata/pata_via.c
index b08e6e0..45657ca 100644
--- a/drivers/ata/pata_via.c
+++ b/drivers/ata/pata_via.c
@@ -62,7 +62,7 @@
 #include <linux/dmi.h>
 
 #define DRV_NAME "pata_via"
-#define DRV_VERSION "0.3.3"
+#define DRV_VERSION "0.3.4"
 
 /*
  *	The following comes directly from Vojtech Pavlik's ide/pci/via82cxxx
@@ -136,6 +136,9 @@ static const struct via_isa_bridge {
 	{ NULL }
 };
 
+struct via_port {
+	u8 cached_device;
+};
 
 /*
  *	Cable special cases
@@ -346,14 +349,70 @@ static void via_set_dmamode(struct ata_port *ap, struct ata_device *adev)
  */
 static void via_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 {
-	struct ata_taskfile tmp_tf;
+	struct ata_ioports *ioaddr = &ap->ioaddr;
+	struct via_port *vp = ap->private_data;
+	unsigned int is_addr = tf->flags & ATA_TFLAG_ISADDR;
+	int newctl = 0;
+
+	if (tf->ctl != ap->last_ctl) {
+		iowrite8(tf->ctl, ioaddr->ctl_addr);
+		ap->last_ctl = tf->ctl;
+		ata_wait_idle(ap);
+		newctl = 1;
+	}
+
+	if (tf->flags & ATA_TFLAG_DEVICE) {
+		iowrite8(tf->device, ioaddr->device_addr);
+		vp->cached_device = tf->device;
+	} else if (newctl)
+		iowrite8(vp->cached_device, ioaddr->device_addr);
+
+	if (is_addr && (tf->flags & ATA_TFLAG_LBA48)) {
+		WARN_ON_ONCE(!ioaddr->ctl_addr);
+		iowrite8(tf->hob_feature, ioaddr->feature_addr);
+		iowrite8(tf->hob_nsect, ioaddr->nsect_addr);
+		iowrite8(tf->hob_lbal, ioaddr->lbal_addr);
+		iowrite8(tf->hob_lbam, ioaddr->lbam_addr);
+		iowrite8(tf->hob_lbah, ioaddr->lbah_addr);
+		VPRINTK("hob: feat 0x%X nsect 0x%X, lba 0x%X 0x%X 0x%X\n",
+			tf->hob_feature,
+			tf->hob_nsect,
+			tf->hob_lbal,
+			tf->hob_lbam,
+			tf->hob_lbah);
+	}
 
-	if (ap->ctl != ap->last_ctl && !(tf->flags & ATA_TFLAG_DEVICE)) {
-		tmp_tf = *tf;
-		tmp_tf.flags |= ATA_TFLAG_DEVICE;
-		tf = &tmp_tf;
+	if (is_addr) {
+		iowrite8(tf->feature, ioaddr->feature_addr);
+		iowrite8(tf->nsect, ioaddr->nsect_addr);
+		iowrite8(tf->lbal, ioaddr->lbal_addr);
+		iowrite8(tf->lbam, ioaddr->lbam_addr);
+		iowrite8(tf->lbah, ioaddr->lbah_addr);
+		VPRINTK("feat 0x%X nsect 0x%X lba 0x%X 0x%X 0x%X\n",
+			tf->feature,
+			tf->nsect,
+			tf->lbal,
+			tf->lbam,
+			tf->lbah);
 	}
-	ata_sff_tf_load(ap, tf);
+
+	ata_wait_idle(ap);
+}
+
+static int via_port_start(struct ata_port *ap)
+{
+	struct via_port *vp;
+	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
+
+	int ret = ata_sff_port_start(ap);
+	if (ret < 0)
+		return ret;
+
+	vp = devm_kzalloc(&pdev->dev, sizeof(struct via_port), GFP_KERNEL);
+	if (vp == NULL)
+		return -ENOMEM;
+	ap->private_data = vp;
+	return 0;
 }
 
 static struct scsi_host_template via_sht = {
@@ -367,6 +426,7 @@ static struct ata_port_operations via_port_ops = {
 	.set_dmamode	= via_set_dmamode,
 	.prereset	= via_pre_reset,
 	.sff_tf_load	= via_tf_load,
+	.port_start	= via_port_start,
 };
 
 static struct ata_port_operations via_port_ops_noirq = {

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