2.6.15 kernel, VT8251 southbridge & no DMA

Message

solatis · Post by **solatis** » Sat Jan 07, 2006 1:28 pm

Hello,

I recently bought a motherboard with a VT8251 south bridge; stupid me, would never do it again if i knew that southbridge was so badly supported.

Anyway, I know that the SATA2 controller still isn't supported, but normal IDE disks should be supported according to this kernel patch:

http://www.uwsg.iu.edu/hypermail/linux/ ... /0172.html

I can confirm that this patch is inside my kernel:

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solatis3 linux # pwd
/usr/src/linux
solatis3 linux # cat include/linux/pci_ids.h | grep -i '8251'
#define PCI_DEVICE_ID_VIA_8251          0x3287
solatis3 linux # cat drivers/ide/pci/via82cxxx.c | grep -i 'vt8251'
        { "vt8251",     PCI_DEVICE_ID_VIA_8251,     0x00, 0x2f, VIA_UDMA_133 | VIA_BAD_AST },
solatis3 linux #

And over here, I can see that I really have a VT8251 southbridge:

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solatis3 linux # lspci | grep VT8251
00:0f.0 IDE interface: VIA Technologies, Inc. VT8251 AHCI/SATA 4-Port Controller
00:11.7 Host bridge: VIA Technologies, Inc. VT8251 Ultra VLINK Controller
00:13.0 PCI bridge: VIA Technologies, Inc. VT8251 PCI to PCIE Bridge
02:00.0 PCI bridge: VIA Technologies, Inc. VT8251 PCIE Root Port
02:00.1 PCI bridge: VIA Technologies, Inc. VT8251 PCIE Root Port
solatis3 linux #

and well... if I try to do a hdparm to set DMA to on, I get a permission denied:

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solatis3 linux # hdparm /dev/hda

/dev/hda:
 multcount    =  0 (off)
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)
 geometry     = 65535/16/63, sectors = 41174138880, start = 0
solatis3 linux # hdparm -d1 /dev/hda

/dev/hda:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)
solatis3 linux #

... and I have no idea what I might be doing wrong. I got the kernel from a kernel.org mirror, built it using "genkernel all" and the via82cxxx kernel module is loaded and in memory. Anyone has any idea at all how to fix this, what I can do to enable DMA support?

solatis · Post by **solatis** » Sun Jan 08, 2006 1:29 pm

*bump* ... so no one has any idea where to look ?

solatis · Post by **solatis** » Wed Jan 11, 2006 2:06 pm

Ok, finally figured out what the problem was (and posting it here for reference for other people); you have to compile this module inside the kernel, not as module... so genkernel with cold/hotplug will not work...

nbensa · Post by **nbensa** » Fri Mar 17, 2006 1:48 am

solatis wrote:Ok, finally figured out what the problem was (and posting it here for reference for other people); you have to compile this module inside the kernel, not as module... so genkernel with cold/hotplug will not work...

It will, but you'll need to load via82cxxx before anything else.