[PATCH] libata: reimplement ata_set_mode() using xfer_mask helpers

Use xfer_mask helpers to determine transfer mode.  This rewrite also
makes transfer mode determination done before any actual
configuration.  This patch doesn't result in any functional changes.

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

1 files changed, 79 insertions, 154 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 88495127efb2..d211f0b1d721 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -65,11 +65,9 @@ static unsigned int ata_dev_init_params(struct ata_port *ap,
                                         struct ata_device *dev);
 static void ata_set_mode(struct ata_port *ap);
 static void ata_dev_set_xfermode(struct ata_port *ap, struct ata_device *dev);
-static unsigned int ata_get_mode_mask(const struct ata_port *ap, int shift);
+static unsigned int ata_dev_xfermask(struct ata_port *ap,
+                                     struct ata_device *dev);
 static int fgb(u32 bitmap);
-static int ata_choose_xfer_mode(const struct ata_port *ap,
-                                u8 *xfer_mode_out,
-                                unsigned int *xfer_shift_out);
 
 static unsigned int ata_unique_id = 1;
 static struct workqueue_struct *ata_wq;
@@ -1776,51 +1774,42 @@ static void ata_dev_set_mode(struct ata_port *ap, struct ata_device *dev)
 
 static int ata_host_set_pio(struct ata_port *ap)
 {
-        unsigned int mask;
-        int x, i;
-        u8 base, xfer_mode;
-
-        mask = ata_get_mode_mask(ap, ATA_SHIFT_PIO);
-        x = fgb(mask);
-        if (x < 0) {
-                printk(KERN_WARNING "ata%u: no PIO support\n", ap->id);
-                return -1;
-        }
-
-        base = base_from_shift(ATA_SHIFT_PIO);
-        xfer_mode = base + x;
-
-        DPRINTK("base 0x%x xfer_mode 0x%x mask 0x%x x %d\n",
-                (int)base, (int)xfer_mode, mask, x);
+        int i;
 
         for (i = 0; i < ATA_MAX_DEVICES; i++) {
                 struct ata_device *dev = &ap->device[i];
-                if (ata_dev_present(dev)) {
-                        dev->pio_mode = xfer_mode;
-                        dev->xfer_mode = xfer_mode;
-                        dev->xfer_shift = ATA_SHIFT_PIO;
-                        if (ap->ops->set_piomode)
-                                ap->ops->set_piomode(ap, dev);
+
+                if (!ata_dev_present(dev))
+                        continue;
+
+                if (!dev->pio_mode) {
+                        printk(KERN_WARNING "ata%u: no PIO support\n", ap->id);
+                        return -1;
                 }
+
+                dev->xfer_mode = dev->pio_mode;
+                dev->xfer_shift = ATA_SHIFT_PIO;
+                if (ap->ops->set_piomode)
+                        ap->ops->set_piomode(ap, dev);
         }
 
         return 0;
 }
 
-static void ata_host_set_dma(struct ata_port *ap, u8 xfer_mode,
-                            unsigned int xfer_shift)
+static void ata_host_set_dma(struct ata_port *ap)
 {
         int i;
 
         for (i = 0; i < ATA_MAX_DEVICES; i++) {
                 struct ata_device *dev = &ap->device[i];
-                if (ata_dev_present(dev)) {
-                        dev->dma_mode = xfer_mode;
-                        dev->xfer_mode = xfer_mode;
-                        dev->xfer_shift = xfer_shift;
-                        if (ap->ops->set_dmamode)
-                                ap->ops->set_dmamode(ap, dev);
-                }
+
+                if (!ata_dev_present(dev) || !dev->dma_mode)
+                        continue;
+
+                dev->xfer_mode = dev->dma_mode;
+                dev->xfer_shift = ata_xfer_mode2shift(dev->dma_mode);
+                if (ap->ops->set_dmamode)
+                        ap->ops->set_dmamode(ap, dev);
         }
 }
 
@@ -1835,28 +1824,34 @@ static void ata_host_set_dma(struct ata_port *ap, u8 xfer_mode,
  */
 static void ata_set_mode(struct ata_port *ap)
 {
-        unsigned int xfer_shift;
-        u8 xfer_mode;
-        int rc;
+        int i, rc;
 
-        /* step 1: always set host PIO timings */
-        rc = ata_host_set_pio(ap);
-        if (rc)
-                goto err_out;
+        /* step 1: calculate xfer_mask */
+        for (i = 0; i < ATA_MAX_DEVICES; i++) {
+                struct ata_device *dev = &ap->device[i];
+                unsigned int xfer_mask;
+
+                if (!ata_dev_present(dev))
+                        continue;
 
-        /* step 2: choose the best data xfer mode */
-        xfer_mode = xfer_shift = 0;
-        rc = ata_choose_xfer_mode(ap, &xfer_mode, &xfer_shift);
+                xfer_mask = ata_dev_xfermask(ap, dev);
+
+                dev->pio_mode = ata_xfer_mask2mode(xfer_mask & ATA_MASK_PIO);
+                dev->dma_mode = ata_xfer_mask2mode(xfer_mask & (ATA_MASK_MWDMA |
+                                                                ATA_MASK_UDMA));
+        }
+
+        /* step 2: always set host PIO timings */
+        rc = ata_host_set_pio(ap);
         if (rc)
                 goto err_out;
 
-        /* step 3: if that xfer mode isn't PIO, set host DMA timings */
-        if (xfer_shift != ATA_SHIFT_PIO)
-                ata_host_set_dma(ap, xfer_mode, xfer_shift);
+        /* step 3: set host DMA timings */
+        ata_host_set_dma(ap);
 
         /* step 4: update devices' xfer mode */
-        ata_dev_set_mode(ap, &ap->device[0]);
-        ata_dev_set_mode(ap, &ap->device[1]);
+        for (i = 0; i < ATA_MAX_DEVICES; i++)
+                ata_dev_set_mode(ap, &ap->device[i]);
 
         if (ap->flags & ATA_FLAG_PORT_DISABLED)
                 return;
@@ -2654,77 +2649,45 @@ static int ata_dma_blacklisted(const struct ata_device *dev)
         return 0;
 }
 
-static unsigned int ata_get_mode_mask(const struct ata_port *ap, int shift)
+/**
+ *      ata_dev_xfermask - Compute supported xfermask of the given device
+ *      @ap: Port on which the device to compute xfermask for resides
+ *      @dev: Device to compute xfermask for
+ *
+ *      Compute supported xfermask of @dev.  This function is
+ *      responsible for applying all known limits including host
+ *      controller limits, device blacklist, etc...
+ *
+ *      LOCKING:
+ *      None.
+ *
+ *      RETURNS:
+ *      Computed xfermask.
+ */
+static unsigned int ata_dev_xfermask(struct ata_port *ap,
+                                     struct ata_device *dev)
 {
-        const struct ata_device *master, *slave;
-        unsigned int mask;
-
-        master = &ap->device[0];
-        slave = &ap->device[1];
+        unsigned long xfer_mask;
+        int i;
 
-        WARN_ON(!ata_dev_present(master) && !ata_dev_present(slave));
+        xfer_mask = ata_pack_xfermask(ap->pio_mask, ap->mwdma_mask,
+                                      ap->udma_mask);
 
-        if (shift == ATA_SHIFT_UDMA) {
-                mask = ap->udma_mask;
-                if (ata_dev_present(master)) {
-                        mask &= (master->id[ATA_ID_UDMA_MODES] & 0xff);
-                        if (ata_dma_blacklisted(master)) {
-                                mask = 0;
-                                ata_pr_blacklisted(ap, master);
-                        }
-                }
-                if (ata_dev_present(slave)) {
-                        mask &= (slave->id[ATA_ID_UDMA_MODES] & 0xff);
-                        if (ata_dma_blacklisted(slave)) {
-                                mask = 0;
-                                ata_pr_blacklisted(ap, slave);
-                        }
-                }
-        }
-        else if (shift == ATA_SHIFT_MWDMA) {
-                mask = ap->mwdma_mask;
-                if (ata_dev_present(master)) {
-                        mask &= (master->id[ATA_ID_MWDMA_MODES] & 0x07);
-                        if (ata_dma_blacklisted(master)) {
-                                mask = 0;
-                                ata_pr_blacklisted(ap, master);
-                        }
-                }
-                if (ata_dev_present(slave)) {
-                        mask &= (slave->id[ATA_ID_MWDMA_MODES] & 0x07);
-                        if (ata_dma_blacklisted(slave)) {
-                                mask = 0;
-                                ata_pr_blacklisted(ap, slave);
-                        }
-                }
-        }
-        else if (shift == ATA_SHIFT_PIO) {
-                mask = ap->pio_mask;
-                if (ata_dev_present(master)) {
-                        /* spec doesn't return explicit support for
-                         * PIO0-2, so we fake it
-                         */
-                        u16 tmp_mode = master->id[ATA_ID_PIO_MODES] & 0x03;
-                        tmp_mode <<= 3;
-                        tmp_mode |= 0x7;
-                        mask &= tmp_mode;
-                }
-                if (ata_dev_present(slave)) {
-                        /* spec doesn't return explicit support for
-                         * PIO0-2, so we fake it
-                         */
-                        u16 tmp_mode = slave->id[ATA_ID_PIO_MODES] & 0x03;
-                        tmp_mode <<= 3;
-                        tmp_mode |= 0x7;
-                        mask &= tmp_mode;
-                }
-        }
-        else {
-                mask = 0xffffffff; /* shut up compiler warning */
-                BUG();
+        /* use port-wide xfermask for now */
+        for (i = 0; i < ATA_MAX_DEVICES; i++) {
+                struct ata_device *d = &ap->device[i];
+                if (!ata_dev_present(d))
+                        continue;
+                xfer_mask &= ata_id_xfermask(d->id);
+                if (ata_dma_blacklisted(d))
+                        xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
         }
 
-        return mask;
+        if (ata_dma_blacklisted(dev))
+                printk(KERN_WARNING "ata%u: dev %u is on DMA blacklist, "
+                       "disabling DMA\n", ap->id, dev->devno);
+
+        return xfer_mask;
 }
 
 /* find greatest bit */
@@ -2741,44 +2704,6 @@ static int fgb(u32 bitmap)
 }
 
 /**
- *      ata_choose_xfer_mode - attempt to find best transfer mode
- *      @ap: Port for which an xfer mode will be selected
- *      @xfer_mode_out: (output) SET FEATURES - XFER MODE code
- *      @xfer_shift_out: (output) bit shift that selects this mode
- *
- *      Based on host and device capabilities, determine the
- *      maximum transfer mode that is amenable to all.
- *
- *      LOCKING:
- *      PCI/etc. bus probe sem.
- *
- *      RETURNS:
- *      Zero on success, negative on error.
- */
-
-static int ata_choose_xfer_mode(const struct ata_port *ap,
-                                u8 *xfer_mode_out,
-                                unsigned int *xfer_shift_out)
-{
-        unsigned int mask, shift;
-        int x, i;
-
-        for (i = 0; i < ARRAY_SIZE(xfer_mode_classes); i++) {
-                shift = xfer_mode_classes[i].shift;
-                mask = ata_get_mode_mask(ap, shift);
-
-                x = fgb(mask);
-                if (x >= 0) {
-                        *xfer_mode_out = xfer_mode_classes[i].base + x;
-                        *xfer_shift_out = shift;
-                        return 0;
-                }
-        }
-
-        return -1;
-}
-
-/**
  *      ata_dev_set_xfermode - Issue SET FEATURES - XFER MODE command
  *      @ap: Port associated with device @dev
  *      @dev: Device to which command will be sent