[PATCH] sata_via: use old SCR access pattern on vt6420

vt6420 has super-fragile SCR registers which can hang the whole
machine if accessed with the wrong timings.  This patch makes sata_via
use SCR registers only during probing and with the same timings as
before (pre new EH), which is proven to work.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 112 insertions, 5 deletions

diff --git a/drivers/scsi/sata_via.c b/drivers/scsi/sata_via.c
index 03baec2191bf..01d40369a8a5 100644
--- a/drivers/scsi/sata_via.c
+++ b/drivers/scsi/sata_via.c
@@ -74,6 +74,7 @@ enum {
 static int svia_init_one (struct pci_dev *pdev, const struct pci_device_id *ent);
 static u32 svia_scr_read (struct ata_port *ap, unsigned int sc_reg);
 static void svia_scr_write (struct ata_port *ap, unsigned int sc_reg, u32 val);
+static void vt6420_error_handler(struct ata_port *ap);
 
 static const struct pci_device_id svia_pci_tbl[] = {
         { 0x1106, 0x3149, PCI_ANY_ID, PCI_ANY_ID, 0, 0, vt6420 },
@@ -107,7 +108,38 @@ static struct scsi_host_template svia_sht = {
         .bios_param             = ata_std_bios_param,
 };
 
-static const struct ata_port_operations svia_sata_ops = {
+static const struct ata_port_operations vt6420_sata_ops = {
+        .port_disable           = ata_port_disable,
+
+        .tf_load                = ata_tf_load,
+        .tf_read                = ata_tf_read,
+        .check_status           = ata_check_status,
+        .exec_command           = ata_exec_command,
+        .dev_select             = ata_std_dev_select,
+
+        .bmdma_setup            = ata_bmdma_setup,
+        .bmdma_start            = ata_bmdma_start,
+        .bmdma_stop             = ata_bmdma_stop,
+        .bmdma_status           = ata_bmdma_status,
+
+        .qc_prep                = ata_qc_prep,
+        .qc_issue               = ata_qc_issue_prot,
+        .data_xfer              = ata_pio_data_xfer,
+
+        .freeze                 = ata_bmdma_freeze,
+        .thaw                   = ata_bmdma_thaw,
+        .error_handler          = vt6420_error_handler,
+        .post_internal_cmd      = ata_bmdma_post_internal_cmd,
+
+        .irq_handler            = ata_interrupt,
+        .irq_clear              = ata_bmdma_irq_clear,
+
+        .port_start             = ata_port_start,
+        .port_stop              = ata_port_stop,
+        .host_stop              = ata_host_stop,
+};
+
+static const struct ata_port_operations vt6421_sata_ops = {
         .port_disable           = ata_port_disable,
 
         .tf_load                = ata_tf_load,
@@ -141,13 +173,13 @@ static const struct ata_port_operations svia_sata_ops = {
         .host_stop              = ata_host_stop,
 };
 
-static struct ata_port_info svia_port_info = {
+static struct ata_port_info vt6420_port_info = {
         .sht            = &svia_sht,
         .host_flags     = ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY,
         .pio_mask       = 0x1f,
         .mwdma_mask     = 0x07,
         .udma_mask      = 0x7f,
-        .port_ops       = &svia_sata_ops,
+        .port_ops       = &vt6420_sata_ops,
 };
 
 MODULE_AUTHOR("Jeff Garzik");
@@ -170,6 +202,81 @@ static void svia_scr_write (struct ata_port *ap, unsigned int sc_reg, u32 val)
         outl(val, ap->ioaddr.scr_addr + (4 * sc_reg));
 }
 
+/**
+ *      vt6420_prereset - prereset for vt6420
+ *      @ap: target ATA port
+ *
+ *      SCR registers on vt6420 are pieces of shit and may hang the
+ *      whole machine completely if accessed with the wrong timing.
+ *      To avoid such catastrophe, vt6420 doesn't provide generic SCR
+ *      access operations, but uses SStatus and SControl only during
+ *      boot probing in controlled way.
+ *
+ *      As the old (pre EH update) probing code is proven to work, we
+ *      strictly follow the access pattern.
+ *
+ *      LOCKING:
+ *      Kernel thread context (may sleep)
+ *
+ *      RETURNS:
+ *      0 on success, -errno otherwise.
+ */
+static int vt6420_prereset(struct ata_port *ap)
+{
+        struct ata_eh_context *ehc = &ap->eh_context;
+        unsigned long timeout = jiffies + (HZ * 5);
+        u32 sstatus, scontrol;
+        int online;
+
+        /* don't do any SCR stuff if we're not loading */
+        if (!ATA_PFLAG_LOADING)
+                goto skip_scr;
+
+        /* Resume phy.  This is the old resume sequence from
+         * __sata_phy_reset().
+         */
+        svia_scr_write(ap, SCR_CONTROL, 0x300);
+        svia_scr_read(ap, SCR_CONTROL); /* flush */
+
+        /* wait for phy to become ready, if necessary */
+        do {
+                msleep(200);
+                if ((svia_scr_read(ap, SCR_STATUS) & 0xf) != 1)
+                        break;
+        } while (time_before(jiffies, timeout));
+
+        /* open code sata_print_link_status() */
+        sstatus = svia_scr_read(ap, SCR_STATUS);
+        scontrol = svia_scr_read(ap, SCR_CONTROL);
+
+        online = (sstatus & 0xf) == 0x3;
+
+        ata_port_printk(ap, KERN_INFO,
+                        "SATA link %s 1.5 Gbps (SStatus %X SControl %X)\n",
+                        online ? "up" : "down", sstatus, scontrol);
+
+        /* SStatus is read one more time */
+        svia_scr_read(ap, SCR_STATUS);
+
+        if (!online) {
+                /* tell EH to bail */
+                ehc->i.action &= ~ATA_EH_RESET_MASK;
+                return 0;
+        }
+
+ skip_scr:
+        /* wait for !BSY */
+        ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
+
+        return 0;
+}
+
+static void vt6420_error_handler(struct ata_port *ap)
+{
+        return ata_bmdma_drive_eh(ap, vt6420_prereset, ata_std_softreset,
+                                  NULL, ata_std_postreset);
+}
+
 static const unsigned int svia_bar_sizes[] = {
         8, 4, 8, 4, 16, 256
 };
@@ -210,7 +317,7 @@ static void vt6421_init_addrs(struct ata_probe_ent *probe_ent,
 static struct ata_probe_ent *vt6420_init_probe_ent(struct pci_dev *pdev)
 {
         struct ata_probe_ent *probe_ent;
-        struct ata_port_info *ppi = &svia_port_info;
+        struct ata_port_info *ppi = &vt6420_port_info;
 
         probe_ent = ata_pci_init_native_mode(pdev, &ppi, ATA_PORT_PRIMARY | ATA_PORT_SECONDARY);
         if (!probe_ent)
@@ -239,7 +346,7 @@ static struct ata_probe_ent *vt6421_init_probe_ent(struct pci_dev *pdev)
 
         probe_ent->sht          = &svia_sht;
         probe_ent->host_flags   = ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY;
-        probe_ent->port_ops     = &svia_sata_ops;
+        probe_ent->port_ops     = &vt6421_sata_ops;
         probe_ent->n_ports      = N_PORTS;
         probe_ent->irq          = pdev->irq;
         probe_ent->irq_flags    = IRQF_SHARED;