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amd74xx: workaround unreliable AltStatus register for nVidia controllers
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It seems that on some nVidia controllers using AltStatus register
can be unreliable so default to Status register if the PCI device
is in Compatibility Mode.  In order to achieve this:

* Add ide_pci_is_in_compatibility_mode() inline helper to <linux/ide.h>.

* Add IDE_HFLAG_BROKEN_ALTSTATUS host flag and set it in amd74xx host
  driver for nVidia controllers in Compatibility Mode.

* Teach actual_try_to_identify() and drive_is_ready() about the new flag.

This fixes the regression caused by removal of CONFIG_IDEPCI_SHARE_IRQ
config option in 2.6.25 and using AltStatus register unconditionally when
available (kernel.org bugs #11659 and #10216).

[ Moreover for CONFIG_IDEPCI_SHARE_IRQ=y (which is what most people
  and distributions use) it never worked correctly. ]

Thanks to Remy LABENE and Lars Winterfeld for help with debugging the problem.

More info at:
http://bugzilla.kernel.org/show_bug.cgi?id=11659
http://bugzilla.kernel.org/show_bug.cgi?id=10216

Reported-by: Remy LABENE <remy.labene@free.fr>
Tested-by: Remy LABENE <remy.labene@free.fr>
Tested-by: Lars Winterfeld <lars.winterfeld@tu-ilmenau.de>
Acked-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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Bartlomiej Zolnierkiewicz committed Dec 2, 2008
1 parent f9e3326 commit 6636487
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Showing 4 changed files with 22 additions and 3 deletions.
11 changes: 10 additions & 1 deletion drivers/ide/amd74xx.c
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
* IDE driver for Linux.
*
* Copyright (c) 2000-2002 Vojtech Pavlik
* Copyright (c) 2007 Bartlomiej Zolnierkiewicz
* Copyright (c) 2007-2008 Bartlomiej Zolnierkiewicz
*
* Based on the work of:
* Andre Hedrick
Expand Down Expand Up @@ -263,6 +263,15 @@ static int __devinit amd74xx_probe(struct pci_dev *dev, const struct pci_device_
d.udma_mask = ATA_UDMA5;
}

/*
* It seems that on some nVidia controllers using AltStatus
* register can be unreliable so default to Status register
* if the device is in Compatibility Mode.
*/
if (dev->vendor == PCI_VENDOR_ID_NVIDIA &&
ide_pci_is_in_compatibility_mode(dev))
d.host_flags |= IDE_HFLAG_BROKEN_ALTSTATUS;

printk(KERN_INFO "%s %s: UDMA%s controller\n",
d.name, pci_name(dev), amd_dma[fls(d.udma_mask) - 1]);

Expand Down
3 changes: 2 additions & 1 deletion drivers/ide/ide-iops.c
Original file line number Diff line number Diff line change
Expand Up @@ -468,7 +468,8 @@ int drive_is_ready (ide_drive_t *drive)
* an interrupt with another pci card/device. We make no assumptions
* about possible isa-pnp and pci-pnp issues yet.
*/
if (hwif->io_ports.ctl_addr)
if (hwif->io_ports.ctl_addr &&
(hwif->host_flags & IDE_HFLAG_BROKEN_ALTSTATUS) == 0)
stat = hwif->tp_ops->read_altstatus(hwif);
else
/* Note: this may clear a pending IRQ!! */
Expand Down
3 changes: 2 additions & 1 deletion drivers/ide/ide-probe.c
Original file line number Diff line number Diff line change
Expand Up @@ -266,7 +266,8 @@ static int actual_try_to_identify (ide_drive_t *drive, u8 cmd)
/* take a deep breath */
msleep(50);

if (io_ports->ctl_addr) {
if (io_ports->ctl_addr &&
(hwif->host_flags & IDE_HFLAG_BROKEN_ALTSTATUS) == 0) {
a = tp_ops->read_altstatus(hwif);
s = tp_ops->read_status(hwif);
if ((a ^ s) & ~ATA_IDX)
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8 changes: 8 additions & 0 deletions include/linux/ide.h
Original file line number Diff line number Diff line change
Expand Up @@ -1296,6 +1296,13 @@ extern int __ide_pci_register_driver(struct pci_driver *driver, struct module *o
#define ide_pci_register_driver(d) pci_register_driver(d)
#endif

static inline int ide_pci_is_in_compatibility_mode(struct pci_dev *dev)
{
if ((dev->class >> 8) == PCI_CLASS_STORAGE_IDE && (dev->class & 5) != 5)
return 1;
return 0;
}

void ide_pci_setup_ports(struct pci_dev *, const struct ide_port_info *, int,
hw_regs_t *, hw_regs_t **);
void ide_setup_pci_noise(struct pci_dev *, const struct ide_port_info *);
Expand Down Expand Up @@ -1375,6 +1382,7 @@ enum {
IDE_HFLAG_IO_32BIT = (1 << 24),
/* unmask IRQs */
IDE_HFLAG_UNMASK_IRQS = (1 << 25),
IDE_HFLAG_BROKEN_ALTSTATUS = (1 << 26),
/* serialize ports if DMA is possible (for sl82c105) */
IDE_HFLAG_SERIALIZE_DMA = (1 << 27),
/* force host out of "simplex" mode */
Expand Down

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