linux-kernel - Re: [PATCH] ide-cd: Handle strange interrupt on the Intel ESB2

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Message-ID: <58cb370e0612051523t2feba049rae830c9fa593b1c1@mail.gmail.com>
Date:	Wed, 6 Dec 2006 00:23:03 +0100
From:	"Bartlomiej Zolnierkiewicz" <bzolnier@...il.com>
To:	Alan <alan@...rguk.ukuu.org.uk>
Cc:	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	akpm@...l.org, "Jeff Garzik" <jgarzik@...ox.com>,
	"Tejun Heo" <htejun@...il.com>
Subject: Re: [PATCH] ide-cd: Handle strange interrupt on the Intel ESB2

[ added Jeff and Tejun to cc: ]

On 12/4/06, Alan <alan@...rguk.ukuu.org.uk> wrote:
> The ESB2 appears to emit spurious DMA interrupts when configured for
> native mode and handling ATAPI devices. Stratus were able to pin this bug
> down and produce a patch. This is a rework which applies the fixup only
> to the ESB2 (for now). We can apply it to other chips later if the same
> problem is found.

Looks good but aren't this trying to fix the same ICH
issue that is fixed in libata by ap->ops->irq_clear(ap)?

[ please see Tejun's mail: http://lkml.org/lkml/2006/11/15/94 ]

If so shouldn't we apply this fix for all ICH5/6/7/8 chipsets?

> This code has been tested and confirmed to fix the problem on the tested
> systems.

Also shouldn't the fix be in IRQ handler?  Currently the fix is limited
to ide-cd driver which seems to be the wrong place as the problem
is supposed to happen also when using other IDE device drivers
or/and other ATA/ATAPI devices?

> Signed-off-by: Alan Cox <alan@...hat.com>
> (Most of the hard work done by Stratus however)
>
> diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.19-rc6-mm1/drivers/ide/ide-cd.c linux-2.6.19-rc6-mm1/drivers/ide/ide-cd.c
> --- linux.vanilla-2.6.19-rc6-mm1/drivers/ide/ide-cd.c   2006-11-24 13:58:06.000000000 +0000
> +++ linux-2.6.19-rc6-mm1/drivers/ide/ide-cd.c   2006-12-01 19:24:58.000000000 +0000
> @@ -687,8 +687,15 @@
>  static int cdrom_decode_status(ide_drive_t *drive, int good_stat, int *stat_ret)
>  {
>         struct request *rq = HWGROUP(drive)->rq;
> +       ide_hwif_t *hwif = HWIF(drive);
>         int stat, err, sense_key;
>
> +       /* We may have bogus DMA interrupts in PIO state here */
> +       if (HWIF(drive)->dma_status && hwif->atapi_irq_bogon) {
> +               stat = hwif->INB(hwif->dma_status);
> +               /* Should we force the bit as well ? */
> +               hwif->OUTB(stat, hwif->dma_status);
> +       }
>         /* Check for errors. */
>         stat = HWIF(drive)->INB(IDE_STATUS_REG);
>         if (stat_ret)
> diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.19-rc6-mm1/drivers/ide/pci/piix.c linux-2.6.19-rc6-mm1/drivers/ide/pci/piix.c
> --- linux.vanilla-2.6.19-rc6-mm1/drivers/ide/pci/piix.c 2006-11-24 13:58:29.000000000 +0000
> +++ linux-2.6.19-rc6-mm1/drivers/ide/pci/piix.c 2006-12-01 19:20:46.000000000 +0000
> @@ -473,6 +473,10 @@
>                 /* This is a painful system best to let it self tune for now */
>                 return;
>         }
> +       /* ESB2 appears to generate spurious DMA interrupts in PIO mode
> +          when in native mode */
> +       if (hwif->pci_dev->device == PCI_DEVICE_ID_INTEL_ESB2_18)
> +               hwif->atapi_irq_bogon = 1;
>
>         hwif->autodma = 0;
>         hwif->tuneproc = &piix_tune_drive;
> diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.19-rc6-mm1/include/linux/ide.h linux-2.6.19-rc6-mm1/include/linux/ide.h
> --- linux.vanilla-2.6.19-rc6-mm1/include/linux/ide.h    2006-11-24 13:58:12.000000000 +0000
> +++ linux-2.6.19-rc6-mm1/include/linux/ide.h    2006-12-01 19:16:27.000000000 +0000
> @@ -796,6 +796,7 @@
>         unsigned        sg_mapped  : 1; /* sg_table and sg_nents are ready */
>         unsigned        no_io_32bit : 1; /* 1 = can not do 32-bit IO ops */
>         unsigned        err_stops_fifo : 1; /* 1=data FIFO is cleared by an error */
> +       unsigned        atapi_irq_bogon : 1; /* Generates spurious DMA interrupts in PIO mode */
>
>         struct device   gendev;
>         struct completion gendev_rel_comp; /* To deal with device release() */
-
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