[libata] pata_amd: program FIFO

With 32bit PIO we can use the posted write buffers, but only for 32bit I/O
cycles.  This means we must disable the FIFO for ATAPI where a final 16bit
cycle may occur.

Rework the FIFO logic so that we disable the FIFO then selectively
re-enable it when we set the timings on AMD devices.  Also fix a case
where we scribbled on PCI config 0x41 of Nvidia chips when we shouldn't.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 59 insertions, 17 deletions

diff --git a/drivers/ata/pata_amd.c b/drivers/ata/pata_amd.c
index 63719ab9ea44..115b1cd6dcf5 100644
--- a/drivers/ata/pata_amd.c
+++ b/drivers/ata/pata_amd.c
@@ -24,7 +24,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME "pata_amd"
-#define DRV_VERSION "0.3.11"
+#define DRV_VERSION "0.4.1"
 
 /**
  *      timing_setup            -       shared timing computation and load
@@ -145,6 +145,13 @@ static int amd_pre_reset(struct ata_link *link, unsigned long deadline)
         return ata_sff_prereset(link, deadline);
 }
 
+/**
+ *      amd_cable_detect        -       report cable type
+ *      @ap: port
+ *
+ *      AMD controller/BIOS setups record the cable type in word 0x42
+ */
+
 static int amd_cable_detect(struct ata_port *ap)
 {
         static const u32 bitmask[2] = {0x03, 0x0C};
@@ -158,6 +165,40 @@ static int amd_cable_detect(struct ata_port *ap)
 }
 
 /**
+ *      amd_fifo_setup          -       set the PIO FIFO for ATA/ATAPI
+ *      @ap: ATA interface
+ *      @adev: ATA device
+ *
+ *      Set the PCI fifo for this device according to the devices present
+ *      on the bus at this point in time. We need to turn the post write buffer
+ *      off for ATAPI devices as we may need to issue a word sized write to the
+ *      device as the final I/O
+ */
+
+static void amd_fifo_setup(struct ata_port *ap)
+{
+        struct ata_device *adev;
+        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
+        static const u8 fifobit[2] = { 0xC0, 0x30};
+        u8 fifo = fifobit[ap->port_no];
+        u8 r;
+
+
+        ata_for_each_dev(adev, &ap->link, ENABLED) {
+                if (adev->class == ATA_DEV_ATAPI)
+                        fifo = 0;
+        }
+        if (pdev->device == PCI_DEVICE_ID_AMD_VIPER_7411) /* FIFO is broken */
+                fifo = 0;
+
+        /* On the later chips the read prefetch bits become no-op bits */
+        pci_read_config_byte(pdev, 0x41, &r);
+        r &= ~fifobit[ap->port_no];
+        r |= fifo;
+        pci_write_config_byte(pdev, 0x41, r);
+}
+
+/**
  *      amd33_set_piomode       -       set initial PIO mode data
  *      @ap: ATA interface
  *      @adev: ATA device
@@ -167,21 +208,25 @@ static int amd_cable_detect(struct ata_port *ap)
 
 static void amd33_set_piomode(struct ata_port *ap, struct ata_device *adev)
 {
+        amd_fifo_setup(ap);
         timing_setup(ap, adev, 0x40, adev->pio_mode, 1);
 }
 
 static void amd66_set_piomode(struct ata_port *ap, struct ata_device *adev)
 {
+        amd_fifo_setup(ap);
         timing_setup(ap, adev, 0x40, adev->pio_mode, 2);
 }
 
 static void amd100_set_piomode(struct ata_port *ap, struct ata_device *adev)
 {
+        amd_fifo_setup(ap);
         timing_setup(ap, adev, 0x40, adev->pio_mode, 3);
 }
 
 static void amd133_set_piomode(struct ata_port *ap, struct ata_device *adev)
 {
+        amd_fifo_setup(ap);
         timing_setup(ap, adev, 0x40, adev->pio_mode, 4);
 }
 
@@ -397,6 +442,16 @@ static struct ata_port_operations nv133_port_ops = {
         .set_dmamode    = nv133_set_dmamode,
 };
 
+static void amd_clear_fifo(struct pci_dev *pdev)
+{
+        u8 fifo;
+        /* Disable the FIFO, the FIFO logic will re-enable it as
+           appropriate */
+        pci_read_config_byte(pdev, 0x41, &fifo);
+        fifo &= 0x0F;
+        pci_write_config_byte(pdev, 0x41, fifo);
+}
+
 static int amd_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
 {
         static const struct ata_port_info info[10] = {
@@ -503,14 +558,8 @@ static int amd_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
 
         if (type < 3)
                 ata_pci_bmdma_clear_simplex(pdev);
-
-        /* Check for AMD7411 */
-        if (type == 3)
-                /* FIFO is broken */
-                pci_write_config_byte(pdev, 0x41, fifo & 0x0F);
-        else
-                pci_write_config_byte(pdev, 0x41, fifo | 0xF0);
-
+        if (pdev->vendor == PCI_VENDOR_ID_AMD)
+                amd_clear_fifo(pdev);
         /* Cable detection on Nvidia chips doesn't work too well,
          * cache BIOS programmed UDMA mode.
          */
@@ -536,18 +585,11 @@ static int amd_reinit_one(struct pci_dev *pdev)
                 return rc;
 
         if (pdev->vendor == PCI_VENDOR_ID_AMD) {
-                u8 fifo;
-                pci_read_config_byte(pdev, 0x41, &fifo);
-                if (pdev->device == PCI_DEVICE_ID_AMD_VIPER_7411)
-                        /* FIFO is broken */
-                        pci_write_config_byte(pdev, 0x41, fifo & 0x0F);
-                else
-                        pci_write_config_byte(pdev, 0x41, fifo | 0xF0);
+                amd_clear_fifo(pdev);
                 if (pdev->device == PCI_DEVICE_ID_AMD_VIPER_7409 ||
                     pdev->device == PCI_DEVICE_ID_AMD_COBRA_7401)
                         ata_pci_bmdma_clear_simplex(pdev);
         }
-
         ata_host_resume(host);
         return 0;
 }