2010-01-16 23:59:24

by Bart Hartgers

Subject: [patch 1/2] sata_via: Correctly setup PIO/DMA for pata slave on vt6421.

Before only the timings for master were set. Datasheet can be found
here: ftp://ftp.vtbridge.org/Docs/Storage/DS_VT6421A_100_CCPL.PDF
Surprisingly, a slave drive works without this patch. According to the
datasheet, the controller by default derives the DMA mode from the
Set Features command issued to a drive. Not sure about the PIO
timings, though. The real problem is that the timings for the master
effectively are the ones tuned for the slave. If these support
different UDMA-settings, there is trouble, especially when the slave
supports a higher UDMA than the master.

Anyhow, using the same mechanism for both master and slave seems like
a good idea.

Signed-off-by: Bart Hartgers <[email protected]>
---
Index: linux-2.6.33-rc4/drivers/ata/sata_via.c
===================================================================
--- linux-2.6.33-rc4.orig/drivers/ata/sata_via.c 2010-01-16 22:28:13.000000000 +0100
+++ linux-2.6.33-rc4/drivers/ata/sata_via.c 2010-01-16 22:29:30.000000000 +0100
@@ -44,7 +44,7 @@
#include <linux/libata.h>

#define DRV_NAME "sata_via"
-#define DRV_VERSION "2.4"
+#define DRV_VERSION "2.5"

/*
* vt8251 is different from other sata controllers of VIA. It has two
@@ -392,14 +392,16 @@ static void vt6421_set_pio_mode(struct a
{
struct pci_dev *pdev = to_pci_dev(ap->host->dev);
static const u8 pio_bits[] = { 0xA8, 0x65, 0x65, 0x31, 0x20 };
- pci_write_config_byte(pdev, PATA_PIO_TIMING, pio_bits[adev->pio_mode - XFER_PIO_0]);
+ pci_write_config_byte(pdev, PATA_PIO_TIMING - adev->devno,
+ pio_bits[adev->pio_mode - XFER_PIO_0]);
}

static void vt6421_set_dma_mode(struct ata_port *ap, struct ata_device *adev)
{
struct pci_dev *pdev = to_pci_dev(ap->host->dev);
static const u8 udma_bits[] = { 0xEE, 0xE8, 0xE6, 0xE4, 0xE2, 0xE1, 0xE0, 0xE0 };
- pci_write_config_byte(pdev, PATA_UDMA_TIMING, udma_bits[adev->dma_mode - XFER_UDMA_0]);
+ pci_write_config_byte(pdev, PATA_UDMA_TIMING - adev->devno,
+ udma_bits[adev->dma_mode - XFER_UDMA_0]);
}

static const unsigned int svia_bar_sizes[] = {

--

2010-01-20 03:27:14

by Tejun Heo

Subject: Re: [patch 1/2] sata_via: Correctly setup PIO/DMA for pata slave on vt6421.

On 01/17/2010 08:56 AM, Bart Hartgers wrote:
> Before only the timings for master were set. Datasheet can be found
> here: ftp://ftp.vtbridge.org/Docs/Storage/DS_VT6421A_100_CCPL.PDF
> Surprisingly, a slave drive works without this patch. According to the
> datasheet, the controller by default derives the DMA mode from the
> Set Features command issued to a drive. Not sure about the PIO
> timings, though. The real problem is that the timings for the master
> effectively are the ones tuned for the slave. If these support
> different UDMA-settings, there is trouble, especially when the slave
> supports a higher UDMA than the master.
>
> Anyhow, using the same mechanism for both master and slave seems like
> a good idea.
>
> Signed-off-by: Bart Hartgers <[email protected]>

Acked-by: Tejun Heo <[email protected]>

Thanks.

--
tejun

2010-01-20 19:35:22

by Jeff Garzik

Subject: Re: [patch 1/2] sata_via: Correctly setup PIO/DMA for pata slave on vt6421.

On 01/16/2010 06:56 PM, Bart Hartgers wrote:
> Before only the timings for master were set. Datasheet can be found
> here: ftp://ftp.vtbridge.org/Docs/Storage/DS_VT6421A_100_CCPL.PDF
> Surprisingly, a slave drive works without this patch. According to the
> datasheet, the controller by default derives the DMA mode from the
> Set Features command issued to a drive. Not sure about the PIO
> timings, though. The real problem is that the timings for the master
> effectively are the ones tuned for the slave. If these support
> different UDMA-settings, there is trouble, especially when the slave
> supports a higher UDMA than the master.
>
> Anyhow, using the same mechanism for both master and slave seems like
> a good idea.
>
> Signed-off-by: Bart Hartgers<[email protected]>

applied