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Date: Mon, 24 Nov 2008 13:33:42 +0300
From: Sergei Shtylyov <sshtylyov@...mvista.com>
To: Shane McDonald <mcdonald.shane@...il.com>
Cc: bzolnier@...il.com, linux-ide@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Resurrect IT8172 IDE controller driver
Hello.
Shane McDonald wrote:
> diff -uprN a/drivers/ide/it8172.c b/drivers/ide/it8172.c
> --- a/drivers/ide/it8172.c 1969-12-31 18:00:00.000000000 -0600
> +++ b/drivers/ide/it8172.c 2008-11-23 01:06:01.000000000 -0600
> @@ -0,0 +1,205 @@
> +/*
> + *
> + * BRIEF MODULE DESCRIPTION
> + * IT8172 IDE controller support
> + *
> + * Copyright 2000 MontaVista Software Inc.
> + * Author: MontaVista Software, Inc.
> + * stevel@...sta.com or source@...sta.com
>
You can remove the former address, Steve Longerbeam is no longer with
MV (quit long ago). And I think you may add your own copyright now.
> +/*
> + * Prototypes
> + */
>
I see no prototypes here...
> +
> +static void it8172_set_pio_mode(ide_drive_t *drive, const u8 pio)
> +{
> + ide_hwif_t *hwif = HWIF(drive);
> + struct pci_dev *dev = to_pci_dev(hwif->dev);
> + int is_slave = (&hwif->drives[1] == drive);
>
Use simpler "drive->dn & 1" (and drop the useless parens please) --
& can be dropped though as the controller has only a single channel...
> + spin_lock_irqsave(&ide_lock, flags);
>
Don't use ide_lock here please. Moreover, since the controller has
only one channel, you don't need any spinlock here.
> + pci_read_config_word(dev, 0x40, &drive_enables);
> + pci_read_config_dword(dev, 0x44, &drive_timing);
> +
> + /*
> + * FIX! The DIOR/DIOW pulse width and recovery times in port 0x44
>
It's usually FIXME. :-)
> + * are being left at the default values of 8 PCI clocks (242 nsec
> + * for a 33 MHz clock).
It's 240, not 242 ns as 33 is actually 33.333.
> These can be safely shortened at higher
> + * PIO modes. The DIOR/DIOW pulse width and recovery times only
> + * apply to PIO modes, not to the DMA modes.
> + */
>
Not true. They do apply to SW/MW DMA modes -- and if you look at your
own code you'll see that.
> +
> + /*
> + * Enable port 0x44. The IT8172 spec is confused; it calls
> + * this register the "Slave IDE Timing Register", but in fact,
> + * it controls timing for both master and slave drives.
> + */
> + drive_enables |= 0x4000;
>
This is strange because this IDE controller seems to be a clone of
the one in the Intel PIIX chip. However, the spec. I have tellm it's not
an exact clone.
I suggest that you take a close look at drivers/ide/piix.c...
> +
> + if (is_slave) {
> + drive_enables &= 0xc006;
> + if (pio > 1)
> + /* enable prefetch and IORDY sample-point */
> + drive_enables |= 0x0060;
>
IORDY sampling shouldn't be enabled for PIO mode 2 always, only if
the drive supports it.
Prefetch should only be enabled for ATA disks, not the ATAPI devices
> +static void it8172_set_dma_mode(ide_drive_t *drive, const u8 speed)
> +{
> + ide_hwif_t *hwif = HWIF(drive);
> + struct pci_dev *dev = to_pci_dev(hwif->dev);
> + int a_speed = 3 << (drive->dn * 4);
> + int u_flag = 1 << drive->dn;
> + int u_speed = 0;
> + u8 reg48, reg4a;
> +
> + const u8 mwdma_to_pio[] = { 0, 3, 4 };
> + u8 pio;
> +
> + pci_read_config_byte(dev, 0x48, ®48);
> + pci_read_config_byte(dev, 0x4a, ®4a);
> +
> + if (speed >= XFER_UDMA_0) {
> +
> + /* Setting the DMA cycle time to 2 or 3 PCI clocks
> + * (60 and 91 nsec at 33 MHz PCI clock) seems to cause
> + * BadCRC errors during DMA transfers on some drives,
>
Sigh, such drives should have been blacklisted...
> + * even though both numbers meet the minimum ATAPI-4 spec
> + * of 73 and 54 nsec for UDMA 1 and 2 respectively.
> + * So the faster times are not implemented here.
> + * The good news is that the slower cycle time has
> + * very little affect on transfer performance.
>
This should only affect the write performance, reads.
> + */
> +
> + u_speed = 0 << (drive->dn * 4);
>
I think you're actually setting UltraDMA mode 2 timing regardless of
the mode selected.
The below code only applies to non-UltraDMA modes.
> +
> + if (speed >= XFER_MW_DMA_0)
> + pio = mwdma_to_pio[speed - XFER_MW_DMA_0];
> + else
> + pio = 2;
> +
> + it8172_set_pio_mode(drive, pio);
>
Moreover, I'd suggest to reimplement it as the timing register layout
is different from the original PIIX and additional DMA modes can be
supported: MWDMA0 and SWDMA1.
> +static unsigned int __devinit init_chipset_it8172(struct pci_dev *dev)
> +{
> + unsigned char progif;
> +
> + /*
> + * Place both IDE interfaces into PCI "native" mode
> + */
> + pci_read_config_byte(dev, PCI_CLASS_PROG, &progif);
> + pci_write_config_byte(dev, PCI_CLASS_PROG, progif | 0x05);
> +
> + return dev->irq;
> +}
>
As Alan have said, you can't do that here.
> +static const struct ide_port_info it8172_chipset __devinitdata = {
> + .name = DRV_NAME,
> + .init_chipset = init_chipset_it8172,
> + .port_ops = &it8172_port_ops,
> + .enablebits = {{0x00, 0x00, 0x00}, {0x40, 0x00, 0x01} },
>
Wrong, should be:
.enablebits = {{0x41, 0x80, 0x80}, {0x00, 0x00, 0x00}},
If that doesn't work (firmware doesn't enable the channel), you can leave it all 0s...
> .host_flags = IDE_HFLAG_SINGLE,
> + .pio_mask = ATA_PIO4,
> + .swdma_mask = ATA_SWDMA2_ONLY,
> + .mwdma_mask = ATA_MWDMA12_ONLY,
>
More modes are supportable...
> +static const struct ide_port_info it8172_chipset __devinitdata = {
Please rename this variable to it8172_port_info.
> +};
> +
> +static int __devinit it8172_init_one(struct pci_dev *dev,
> + const struct pci_device_id *id)
> +{
> + if ((!(PCI_FUNC(dev->devfn) & 1) ||
> + (!((dev->class >> 8) == PCI_CLASS_STORAGE_IDE))))
>
Please, don't abuse parens, it should be just:
if (!(PCI_FUNC(dev->devfn) & 1) ||
(dev->class >> 8) != PCI_CLASS_STORAGE_IDE)
> + return -ENODEV; /* IT8172 is more than an IDE controller */
>
And I don't get it: why the first check is needed? Is there another
IDE controller on function 1 that you want to ignore? I doubt it.
> +MODULE_AUTHOR("SteveL@...sta.com");
>
I wonder why Steve didn't specify his full name... :-)
MBR, Sergei
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