it821x: PIO mode setup fixes

* limit max PIO mode to PIO4, this driver doesn't support PIO5 and attempt
  to setup PIO5 by it821x_tuneproc() could result in incorrect PIO timings
  + incorrect base clock being set for controller in the passthrough mode

* move code limiting max PIO according to the pair device capabilities from
  config_it821x_chipset_for_pio() to it821x_tuneproc() so the check is also
  applied for mode change requests coming through ->tuneproc and ->speedproc
  interfaces

* set device speed in it821x_tuneproc()

* in it821x_tune_chipset() call it821x_tuneproc() also if the controller is
  in the smart mode (so the check for pair device max PIO is done)

* rename it821x_tuneproc() to it821x_tune_pio(), then add it821x_tuneproc()
  wrapper which does the max PIO mode check;  it worked by the pure luck
  previously, pio[4] and pio_want[4] arrays were used with index == 255
  so random PIO timings and base clock were set for the controller in the
  passthrough mode, thankfully PIO timings and base clock were corrected
  later by config_it821x_chipset_for_pio() call (but it was not called for
  PIO-only devices during resume and for user requested PIO autotuning)

* remove config_it821x_chipset_for_pio() call from config_chipset_for_dma()
  as the driver sets ->autotune to 1 and ->tuneproc does the proper job now

* convert the last user of config_it821x_chipset_for_pio() to use
  it821x_tuneproc(drive, 255) and remove no longer needed function

While at it:

* fix few comments

* bump driver version

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 58 insertions, 68 deletions

diff --git a/drivers/ide/pci/it821x.c b/drivers/ide/pci/it821x.c
index a132767f7d90..4e1254813ee0 100644
--- a/drivers/ide/pci/it821x.c
+++ b/drivers/ide/pci/it821x.c
@@ -1,8 +1,9 @@
 
 /*
- * linux/drivers/ide/pci/it821x.c               Version 0.09    December 2004
+ * linux/drivers/ide/pci/it821x.c               Version 0.10    Mar 10 2007
  *
  * Copyright (C) 2004           Red Hat <alan@redhat.com>
+ * Copyright (C) 2007           Bartlomiej Zolnierkiewicz
  *
  *  May be copied or modified under the terms of the GNU General Public License
  *  Based in part on the ITE vendor provided SCSI driver.
@@ -104,6 +105,7 @@ static int it8212_noraid;
 /**
  *      it821x_program  -       program the PIO/MWDMA registers
  *      @drive: drive to tune
+ *      @timing: timing info
  *
  *      Program the PIO/MWDMA timing for this channel according to the
  *      current clock.
@@ -127,6 +129,7 @@ static void it821x_program(ide_drive_t *drive, u16 timing)
 /**
  *      it821x_program_udma     -       program the UDMA registers
  *      @drive: drive to tune
+ *      @timing: timing info
  *
  *      Program the UDMA timing for this drive according to the
  *      current clock.
@@ -153,10 +156,9 @@ static void it821x_program_udma(ide_drive_t *drive, u16 timing)
         }
 }
 
-
 /**
  *      it821x_clock_strategy
- *      @hwif: hardware interface
+ *      @drive: drive to set up
  *
  *      Select between the 50 and 66Mhz base clocks to get the best
  *      results for this interface.
@@ -182,8 +184,11 @@ static void it821x_clock_strategy(ide_drive_t *drive)
                 altclock = itdev->want[0][1];
         }
 
-        /* Master doesn't care does the slave ? */
-        if(clock == ATA_ANY)
+        /*
+         * if both clocks can be used for the mode with the higher priority
+         * use the clock needed by the mode with the lower priority
+         */
+        if (clock == ATA_ANY)
                 clock = altclock;
 
         /* Nobody cares - keep the same clock */
@@ -240,37 +245,56 @@ static u8 it821x_ratemask (ide_drive_t *drive)
 }
 
 /**
- *      it821x_tuneproc -       tune a drive
+ *      it821x_tunepio  -       tune a drive
  *      @drive: drive to tune
- *      @mode_wanted: the target operating mode
- *
- *      Load the timing settings for this device mode into the
- *      controller. By the time we are called the mode has been
- *      modified as neccessary to handle the absence of seperate
- *      master/slave timers for MWDMA/PIO.
+ *      @pio: the desired PIO mode
  *
- *      This code is only used in pass through mode.
+ *      Try to tune the drive/host to the desired PIO mode taking into
+ *      the consideration the maximum PIO mode supported by the other
+ *      device on the cable.
  */
 
-static void it821x_tuneproc (ide_drive_t *drive, byte mode_wanted)
+static int it821x_tunepio(ide_drive_t *drive, u8 set_pio)
 {
         ide_hwif_t *hwif        = drive->hwif;
         struct it821x_dev *itdev = ide_get_hwifdata(hwif);
         int unit = drive->select.b.unit;
+        ide_drive_t *pair = &hwif->drives[1 - unit];
 
         /* Spec says 89 ref driver uses 88 */
         static u16 pio[]        = { 0xAA88, 0xA382, 0xA181, 0x3332, 0x3121 };
         static u8 pio_want[]    = { ATA_66, ATA_66, ATA_66, ATA_66, ATA_ANY };
 
-        if(itdev->smart)
-                return;
+        /*
+         * Compute the best PIO mode we can for a given device. We must
+         * pick a speed that does not cause problems with the other device
+         * on the cable.
+         */
+        if (pair) {
+                u8 pair_pio = ide_get_best_pio_mode(pair, 255, 4, NULL);
+                /* trim PIO to the slowest of the master/slave */
+                if (pair_pio < set_pio)
+                        set_pio = pair_pio;
+        }
+
+        if (itdev->smart)
+                goto set_drive_speed;
 
         /* We prefer 66Mhz clock for PIO 0-3, don't care for PIO4 */
-        itdev->want[unit][1] = pio_want[mode_wanted];
+        itdev->want[unit][1] = pio_want[set_pio];
         itdev->want[unit][0] = 1;       /* PIO is lowest priority */
-        itdev->pio[unit] = pio[mode_wanted];
+        itdev->pio[unit] = pio[set_pio];
         it821x_clock_strategy(drive);
         it821x_program(drive, itdev->pio[unit]);
+
+set_drive_speed:
+        return ide_config_drive_speed(drive, XFER_PIO_0 + set_pio);
+}
+
+static void it821x_tuneproc(ide_drive_t *drive, u8 pio)
+{
+        pio = ide_get_best_pio_mode(drive, pio, 4, NULL);
+        (void)it821x_tunepio(drive, pio);
 }
 
 /**
@@ -354,40 +378,6 @@ static void it821x_tune_udma (ide_drive_t *drive, byte mode_wanted)
 }
 
 /**
- *      config_it821x_chipset_for_pio   -       set drive timings
- *      @drive: drive to tune
- *      @speed we want
- *
- *      Compute the best pio mode we can for a given device. We must
- *      pick a speed that does not cause problems with the other device
- *      on the cable.
- */
-
-static void config_it821x_chipset_for_pio (ide_drive_t *drive, byte set_speed)
-{
-        u8 unit = drive->select.b.unit;
-        ide_hwif_t *hwif = drive->hwif;
-        ide_drive_t *pair = &hwif->drives[1-unit];
-        u8 speed = 0, set_pio   = ide_get_best_pio_mode(drive, 255, 5, NULL);
-        u8 pair_pio;
-
-        /* We have to deal with this mess in pairs */
-        if(pair != NULL) {
-                pair_pio = ide_get_best_pio_mode(pair, 255, 5, NULL);
-                /* Trim PIO to the slowest of the master/slave */
-                if(pair_pio < set_pio)
-                        set_pio = pair_pio;
-        }
-        it821x_tuneproc(drive, set_pio);
-        speed = XFER_PIO_0 + set_pio;
-        /* XXX - We trim to the lowest of the pair so the other drive
-           will always be fine at this point until we do hotplug passthru */
-
-        if (set_speed)
-                (void) ide_config_drive_speed(drive, speed);
-}
-
-/**
  *      it821x_dma_read -       DMA hook
  *      @drive: drive for DMA
  *
@@ -450,15 +440,17 @@ static int it821x_tune_chipset (ide_drive_t *drive, byte xferspeed)
         struct it821x_dev *itdev = ide_get_hwifdata(hwif);
         u8 speed                = ide_rate_filter(it821x_ratemask(drive), xferspeed);
 
-        if(!itdev->smart) {
-                switch(speed) {
-                        case XFER_PIO_4:
-                        case XFER_PIO_3:
-                        case XFER_PIO_2:
-                        case XFER_PIO_1:
-                        case XFER_PIO_0:
-                                it821x_tuneproc(drive, (speed - XFER_PIO_0));
-                                break;
+        switch (speed) {
+        case XFER_PIO_4:
+        case XFER_PIO_3:
+        case XFER_PIO_2:
+        case XFER_PIO_1:
+        case XFER_PIO_0:
+                return it821x_tunepio(drive, speed - XFER_PIO_0);
+        }
+
+        if (itdev->smart == 0) {
+                switch (speed) {
                         /* MWDMA tuning is really hard because our MWDMA and PIO
                            timings are kept in the same place. We can switch in the
                            host dma on/off callbacks */
@@ -498,14 +490,12 @@ static int config_chipset_for_dma (ide_drive_t *drive)
 {
         u8 speed        = ide_dma_speed(drive, it821x_ratemask(drive));
 
-        if (speed) {
-                config_it821x_chipset_for_pio(drive, 0);
-                it821x_tune_chipset(drive, speed);
+        if (speed == 0)
+                return 0;
 
-                return ide_dma_enable(drive);
-        }
+        it821x_tune_chipset(drive, speed);
 
-        return 0;
+        return ide_dma_enable(drive);
 }
 
 /**
@@ -523,7 +513,7 @@ static int it821x_config_drive_for_dma (ide_drive_t *drive)
         if (ide_use_dma(drive) && config_chipset_for_dma(drive))
                 return 0;
 
-        config_it821x_chipset_for_pio(drive, 1);
+        it821x_tuneproc(drive, 255);
 
         return -1;
 }