IDE + CPU Scaling problem on Via EPIA systems

IDE + CPU Scaling problem on Via EPIA systems

[gboyce]

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Folks,

While attempting to setup a new server using a Via EPIA-M motherboard 
(Nehemiah processor), I encountered a problem when I enabled CPU Frequency 
scaling via the powernowd daemon.

The system is using software RAID 1 on a pair of IDE drives.  Everything 
goes fine until powernowd is enabled.  At that point I get the following 
errors:

[4294871.703000] hda: dma_timer_expiry: dma status == 0x20
[4294871.703000] hda: DMA timeout retry
[4294871.703000] hda: timeout waiting for DMA
[4294871.703000] hda: status error: status=0x58 { DriveReady SeekComplete 
DataRequest }
[4294871.703000]
[4294871.703000] ide: failed opcode was: unknown
[4294871.703000] hda: drive not ready for command
[4294958.589000] hda: dma_timer_expiry: dma status == 0x20
[4294958.589000] hda: DMA timeout retry
[4294958.589000] hda: timeout waiting for DMA
[4294958.589000] hda: status error: status=0x58 { DriveReady SeekComplete 
DataRequest }
[4294958.589000]
[4294958.589000] ide: failed opcode was: unknown
[4294958.589000] hda: drive not ready for command

I ran the system for an extended time previously with no problem, but at 
this point I did not use powernowd, and I was not using RAID.

The system is running Ubuntu, but I also encountered someone else with the 
same problem on an older Via EPIA system and SuSE.  The ubuntu kernel I'm 
using is 2.6.12-10-386.

I've attached the full dmesg output as well.

For now I'm just going to turn off cpu scaling.  Someday I'd like to use 
it though.  Any suggestions for things I can try?  Or is this perhaps a 
known issue of some sort?

--
Greg

[-- Attachment #2: Type: TEXT/PLAIN, Size: 15887 bytes --]

sor.
[4294667.296000] Using pmtmr for high-res timesource
[4294667.296000] Console: colour VGA+ 80x25
[4294671.344000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
[4294671.345000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
[4294671.377000] Memory: 218888k/229312k available (1416k kernel code, 9816k reserved, 762k data, 224k init, 0k highmem)
[4294671.377000] Checking if this processor honours the WP bit even in supervisor mode... Ok.
[4294671.377000] Calibrating delay loop... 1982.46 BogoMIPS (lpj=991232)
[4294671.398000] Security Framework v1.0.0 initialized
[4294671.398000] SELinux:  Disabled at boot.
[4294671.398000] Mount-cache hash table entries: 512
[4294671.398000] CPU: After generic identify, caps: 0380b03d 00000000 00000000 00000000 00000000 00000000 00000000
[4294671.398000] CPU: L1 I Cache: 64K (32 bytes/line), D cache 64K (32 bytes/line)
[4294671.398000] CPU: L2 Cache: 64K (32 bytes/line)
[4294671.398000] CPU: After all inits, caps: 0380b13d 00000000 00000000 00000000 00000000 0000003d 00000000
[4294671.398000] CPU: Centaur VIA Nehemiah stepping 05
[4294671.398000] Enabling fast FPU save and restore... done.
[4294671.398000] Enabling unmasked SIMD FPU exception support... done.
[4294671.398000] Checking 'hlt' instruction... OK.
[4294671.402000] Checking for popad bug... OK.
[4294671.402000] checking if image is initramfs... it is
[4294672.851000] Freeing initrd memory: 5141k freed
[4294672.857000] ACPI: Looking for DSDT in initrd... not found!
[4294673.050000]  not found!
[4294673.066000] ACPI: setting ELCR to 0200 (from 1e20)
[4294673.126000] NET: Registered protocol family 16
[4294673.126000] EISA bus registered
[4294673.126000] ACPI: bus type pci registered
[4294673.135000] PCI: PCI BIOS revision 2.10 entry at 0xfb260, last bus=1
[4294673.135000] PCI: Using configuration type 1
[4294673.135000] mtrr: v2.0 (20020519)
[4294673.136000] ACPI: Subsystem revision 20050729
[4294673.153000] ACPI: Interpreter enabled
[4294673.153000] ACPI: Using PIC for interrupt routing
[4294673.154000] ACPI: PCI Root Bridge [PCI0] (0000:00)
[4294673.154000] PCI: Probing PCI hardware (bus 00)
[4294673.154000] ACPI: Assume root bridge [\_SB_.PCI0] segment is 0
[4294673.159000] Boot video device is 0000:01:00.0
[4294673.203000] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
[4294673.206000] ACPI: PCI Interrupt Link [LNKA] (IRQs 1 3 4 5 6 7 10 *11 12 14 15)
[4294673.207000] ACPI: PCI Interrupt Link [LNKB] (IRQs 1 3 4 5 6 7 10 11 *12 14 15)
[4294673.208000] ACPI: PCI Interrupt Link [LNKC] (IRQs 1 3 4 5 6 7 *10 11 12 14 15)
[4294673.209000] ACPI: PCI Interrupt Link [LNKD] (IRQs 1 3 4 *5 6 7 10 11 12 14 15)
[4294673.215000] Linux Plug and Play Support v0.97 (c) Adam Belay
[4294673.215000] pnp: PnP ACPI init
[4294673.223000] pnp: PnP ACPI: found 12 devices
[4294673.223000] PnPBIOS: Disabled by ACPI PNP
[4294673.223000] PCI: Using ACPI for IRQ routing
[4294673.223000] PCI: If a device doesn't work, try "pci=routeirq".  If it helps, post a report
[4294673.280000] pnp: 00:01: ioport range 0x400-0x47f could not be reserved
[4294673.280000] pnp: 00:01: ioport range 0x500-0x50f has been reserved
[4294673.281000] audit: initializing netlink socket (disabled)
[4294673.281000] audit: initialized
[4294673.281000] VFS: Disk quotas dquot_6.5.1
[4294673.281000] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[4294673.281000] devfs: 2004-01-31 Richard Gooch (rgooch@atnf.csiro.au)
[4294673.281000] devfs: boot_options: 0x0
[4294673.281000] Initializing Cryptographic API
[4294673.282000] isapnp: Scanning for PnP cards...
[4294673.635000] isapnp: No Plug & Play device found
[4294673.681000] PNP: PS/2 controller doesn't have AUX irq; using default 0xc
[4294673.681000] PNP: PS/2 Controller [PNP0303:PS2K] at 0x60,0x64 irq 112
[4294673.681000] serio: i8042 AUX port at 0x60,0x64 irq 12
[4294673.681000] serio: i8042 KBD port at 0x60,0x64 irq 1
[4294673.681000] Serial: 8250/16550 driver $Revision: 1.90 $ 54 ports, IRQ sharing enabled
[4294673.681000] ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[4294673.681000] ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
[4294673.686000] ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[4294673.687000] ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
[4294673.687000] io scheduler noop registered
[4294673.687000] io scheduler anticipatory registered
[4294673.687000] io scheduler deadline registered
[4294673.687000] io scheduler cfq registered
[4294673.688000] RAMDISK driver initialized: 16 RAM disks of 65536K size 1024 blocksize
[4294673.688000] EISA: Probing bus 0 at eisa.0
[4294673.688000] EISA: Detected 0 cards.
[4294673.688000] NET: Registered protocol family 2
[4294673.697000] IP: routing cache hash table of 2048 buckets, 16Kbytes
[4294673.697000] TCP established hash table entries: 8192 (order: 4, 65536 bytes)
[4294673.697000] TCP bind hash table entries: 8192 (order: 3, 32768 bytes)
[4294673.697000] TCP: Hash tables configured (established 8192 bind 8192)
[4294673.698000] NET: Registered protocol family 8
[4294673.698000] NET: Registered protocol family 20
[4294673.698000] ACPI wakeup devices: 
[4294673.698000] PCI0 USB0 USB1 USB2 USB3 USB4 USB5 USB6 LAN0 AC97 MC97 UAR1 
[4294673.698000] ACPI: (supports S0 S1 S4 S5)
[4294673.699000] Freeing unused kernel memory: 224k freed
[4294673.809000] Capability LSM initialized
[4294673.812000] input: AT Translated Set 2 keyboard on isa0060/serio0
[4294673.847000] NET: Registered protocol family 1
[4294673.895000] Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
[4294673.895000] ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
[4294673.895000] ACPI: bus type ide registered
[4294673.907000] VP_IDE: IDE controller at PCI slot 0000:00:11.1
[4294673.909000] ACPI: PCI Interrupt Link [LNKA] enabled at IRQ 11
[4294673.909000] PCI: setting IRQ 11 as level-triggered
[4294673.909000] ACPI: PCI Interrupt 0000:00:11.1[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
[4294673.909000] PCI: Via IRQ fixup for 0000:00:11.1, from 255 to 11
[4294673.909000] VP_IDE: chipset revision 6
[4294673.909000] VP_IDE: not 100% native mode: will probe irqs later
[4294673.909000] VP_IDE: VIA vt8235 (rev 00) IDE UDMA133 controller on pci0000:00:11.1
[4294673.909000]     ide0: BM-DMA at 0xe000-0xe007, BIOS settings: hda:DMA, hdb:pio
[4294673.909000]     ide1: BM-DMA at 0xe008-0xe00f, BIOS settings: hdc:DMA, hdd:DMA
[4294673.909000] Probing IDE interface ide0...
[4294674.293000] hda: Maxtor 6Y160P0, ATA DISK drive
[4294674.905000] ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
[4294674.905000] Probing IDE interface ide1...
[4294675.697000] hdc: MATSHITACD-RW CW-8123, ATAPI CD/DVD-ROM drive
[4294675.952000] hdd: ST3120026A, ATA DISK drive
[4294676.003000] ide1 at 0x170-0x177,0x376 on irq 15
[4294676.004000] Probing IDE interface ide2...
[4294676.517000] Probing IDE interface ide3...
[4294677.030000] Probing IDE interface ide4...
[4294677.543000] Probing IDE interface ide5...
[4294678.066000] hda: max request size: 1024KiB
[4294678.082000] hda: 320173056 sectors (163928 MB) w/7936KiB Cache, CHS=19929/255/63, UDMA(133)
[4294678.082000] hda: cache flushes supported
[4294678.083000]  /dev/ide/host0/bus0/target0/lun0: p1 p2 p4
[4294678.092000] hdd: max request size: 1024KiB
[4294678.092000] hdd: 234441648 sectors (120034 MB) w/8192KiB Cache, CHS=16383/255/63, UDMA(100)
[4294678.093000] hdd: cache flushes supported
[4294678.093000]  /dev/ide/host0/bus1/target1/lun0: p1
[4294678.106000] hdc: ATAPI 24X DVD-ROM CD-R/RW drive, 2048kB Cache
[4294678.106000] Uniform CD-ROM driver Revision: 3.20
[4294679.003000] Attempting manual resume
[4294679.003000] swsusp: Suspend partition has wrong signature?
[4294679.102000] usbcore: registered new driver usbfs
[4294679.102000] usbcore: registered new driver hub
[4294679.104000] USB Universal Host Controller Interface driver v2.2
[4294679.105000] ACPI: PCI Interrupt 0000:00:10.0[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
[4294679.105000] uhci_hcd 0000:00:10.0: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller
[4294679.167000] uhci_hcd 0000:00:10.0: new USB bus registered, assigned bus number 1
[4294679.167000] uhci_hcd 0000:00:10.0: irq 11, io base 0x0000d400
[4294679.167000] hub 1-0:1.0: USB hub found
[4294679.167000] hub 1-0:1.0: 2 ports detected
[4294679.171000] ACPI: PCI Interrupt Link [LNKB] enabled at IRQ 12
[4294679.171000] PCI: setting IRQ 12 as level-triggered
[4294679.171000] ACPI: PCI Interrupt 0000:00:10.1[B] -> Link [LNKB] -> GSI 12 (level, low) -> IRQ 12
[4294679.171000] uhci_hcd 0000:00:10.1: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (#2)
[4294679.233000] uhci_hcd 0000:00:10.1: new USB bus registered, assigned bus number 2
[4294679.233000] uhci_hcd 0000:00:10.1: irq 12, io base 0x0000d800
[4294679.233000] hub 2-0:1.0: USB hub found
[4294679.233000] hub 2-0:1.0: 2 ports detected
[4294679.237000] ACPI: PCI Interrupt Link [LNKC] enabled at IRQ 10
[4294679.237000] PCI: setting IRQ 10 as level-triggered
[4294679.237000] ACPI: PCI Interrupt 0000:00:10.2[C] -> Link [LNKC] -> GSI 10 (level, low) -> IRQ 10
[4294679.237000] uhci_hcd 0000:00:10.2: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (#3)
[4294679.299000] uhci_hcd 0000:00:10.2: new USB bus registered, assigned bus number 3
[4294679.299000] uhci_hcd 0000:00:10.2: irq 10, io base 0x0000dc00
[4294679.299000] hub 3-0:1.0: USB hub found
[4294679.299000] hub 3-0:1.0: 2 ports detected
[4294679.376000] ACPI: PCI Interrupt Link [LNKD] enabled at IRQ 5
[4294679.376000] PCI: setting IRQ 5 as level-triggered
[4294679.376000] ACPI: PCI Interrupt 0000:00:10.3[D] -> Link [LNKD] -> GSI 5 (level, low) -> IRQ 5
[4294679.376000] ehci_hcd 0000:00:10.3: VIA Technologies, Inc. USB 2.0
[4294679.376000] ehci_hcd 0000:00:10.3: new USB bus registered, assigned bus number 4
[4294679.376000] ehci_hcd 0000:00:10.3: irq 5, io mem 0xde001000
[4294679.376000] ehci_hcd 0000:00:10.3: USB 2.0 initialized, EHCI 1.00, driver 10 Dec 2004
[4294679.376000] hub 4-0:1.0: USB hub found
[4294679.376000] hub 4-0:1.0: 6 ports detected
[4294679.496000] via-rhine.c:v1.10-LK1.2.0-2.6 June-10-2004 Written by Donald Becker
[4294679.496000] ACPI: PCI Interrupt 0000:00:12.0[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
[4294679.500000] eth0: VIA Rhine II at 0x1ec00, 00:40:63:d7:a9:0f, IRQ 11.
[4294679.501000] eth0: MII PHY found at address 1, status 0x786d advertising 05e1 Link 45e1.
[4294680.241000] usb 1-2: new full speed USB device using uhci_hcd and address 2
[4294680.332000] hub 1-2:1.0: USB hub found
[4294680.334000] hub 1-2:1.0: 3 ports detected
[4294680.515000] usb 1-2.1: new full speed USB device using uhci_hcd and address 3
[4294681.577000] usbcore: registered new driver hiddev
[4294681.581000] input: USB HID v1.00 Keyboard [Silitek IBM USB HUB KEYBOARD] on usb-0000:00:10.0-2.1
[4294681.585000] input: USB HID v1.00 Device [Silitek IBM USB HUB KEYBOARD] on usb-0000:00:10.0-2.1
[4294681.585000] usbcore: registered new driver usbhid
[4294681.585000] drivers/usb/input/hid-core.c: v2.01:USB HID core driver
[4294682.633000] ACPI: CPU0 (power states: C1[C1] C2[C2])
[4294682.633000] ACPI: Processor [CPU0] (supports 2 throttling states)
[4294682.745000] md: md driver 0.90.1 MAX_MD_DEVS=256, MD_SB_DISKS=27
[4294682.753000] md: raid1 personality registered as nr 3
[4294682.973000] devfs_mk_dev: could not append to parent for md/0
[4294682.981000] md: md0 stopped.
[4294682.982000] md: bind<hdd1>
[4294682.982000] md: bind<hda2>
[4294682.982000] md: md0: raid array is not clean -- starting background reconstruction
[4294682.983000] raid1: raid set md0 active with 2 out of 2 mirrors
[4294682.985000] .<6>md: syncing RAID array md0
[4294682.985000] md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
[4294682.985000] md: using maximum available idle IO bandwith (but not more than 200000 KB/sec) for reconstruction.
[4294682.985000] md: using 128k window, over a total of 117186048 blocks.
[4294682.985000] md: resuming recovery of md0 from checkpoint.
[4294683.098000] Attempting manual resume
[4294683.098000] swsusp: Suspend partition has wrong signature?
[4294683.124000] kjournald starting.  Commit interval 5 seconds
[4294683.124000] EXT3-fs: mounted filesystem with ordered data mode.
[4294688.371000] Adding 979924k swap on /dev/hda1.  Priority:-1 extents:1
[4294688.473000] EXT3 FS on hda4, internal journal
[4294694.670000] parport: PnPBIOS parport detected.
[4294694.670000] parport0: PC-style at 0x378, irq 7 [PCSPP,TRISTATE,EPP]
[4294694.766000] lp0: using parport0 (interrupt-driven).
[4294694.873000] mice: PS/2 mouse device common for all mice
[4294695.048000] ieee1394: Initialized config rom entry `ip1394'
[4294695.060000] SCSI subsystem initialized
[4294695.084000] sbp2: $Rev: 1219 $ Ben Collins <bcollins@debian.org>
[4294698.654000] device-mapper: 4.4.0-ioctl (2005-01-12) initialised: dm-devel@redhat.com
[4294699.525000] cdrom: open failed.
[4294700.168000] kjournald starting.  Commit interval 5 seconds
[4294700.168000] EXT3 FS on md0, internal journal
[4294700.168000] EXT3-fs: mounted filesystem with ordered data mode.
[4294701.226000] Linux agpgart interface v0.101 (c) Dave Jones
[4294701.247000] agpgart: Detected VIA CLE266 chipset
[4294701.260000] agpgart: AGP aperture is 128M @ 0xd0000000
[4294701.601000] pci_hotplug: PCI Hot Plug PCI Core version: 0.5
[4294701.634000] shpchp: shpc_init : shpc_cap_offset == 0
[4294701.634000] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
[4294701.993000] ohci1394: $Rev: 1250 $ Ben Collins <bcollins@debian.org>
[4294701.993000] ACPI: PCI Interrupt 0000:00:0d.0[A] -> Link [LNKB] -> GSI 12 (level, low) -> IRQ 12
[4294702.061000] ohci1394: fw-host0: OHCI-1394 1.0 (PCI): IRQ=[12]  MMIO=[de000000-de0007ff]  Max Packet=[2048]
[4294703.139000] irda_init()
[4294703.139000] NET: Registered protocol family 23
[4294703.330000] ieee1394: Host added: ID:BUS[0-00:1023]  GUID[004063500001b247]
[4294704.570000] ACPI: PCI Interrupt 0000:00:11.5[C] -> Link [LNKC] -> GSI 10 (level, low) -> IRQ 10
[4294704.570000] PCI: Setting latency timer of device 0000:00:11.5 to 64
[4294709.120000] Real Time Clock Driver v1.12
[4294709.269000] input: PC Speaker
[4294709.806000] Floppy drive(s): fd0 is 1.44M
[4294709.820000] FDC 0 is a post-1991 82077
[4294712.466000] eth0: link up, 100Mbps, full-duplex, lpa 0x45E1
[4294712.500000] NET: Registered protocol family 17
[4294715.559000] NET: Registered protocol family 10
[4294715.559000] Disabled Privacy Extensions on device c02eb280(lo)
[4294715.559000] IPv6 over IPv4 tunneling driver
[4294718.087000] ACPI: Power Button (FF) [PWRF]
[4294718.087000] ACPI: Power Button (CM) [PWRB]
[4294718.483000] ibm_acpi: ec object not found
[4294725.851000] eth0: no IPv6 routers present
[4294788.304000] cdrom: open failed.
[4294788.540000] cdrom: open failed.
[4294850.638000] longhaul: VIA C3 'Nehemiah C' [C5N] CPU detected.  Powersaver supported.
[4294871.703000] hda: dma_timer_expiry: dma status == 0x20
[4294871.703000] hda: DMA timeout retry
[4294871.703000] hda: timeout waiting for DMA
[4294871.703000] hda: status error: status=0x58 { DriveReady SeekComplete DataRequest }
[4294871.703000] 
[4294871.703000] ide: failed opcode was: unknown
[4294871.703000] hda: drive not ready for command
[4294958.589000] hda: dma_timer_expiry: dma status == 0x20
[4294958.589000] hda: DMA timeout retry
[4294958.589000] hda: timeout waiting for DMA
[4294958.589000] hda: status error: status=0x58 { DriveReady SeekComplete DataRequest }
[4294958.589000] 
[4294958.589000] ide: failed opcode was: unknown
[4294958.589000] hda: drive not ready for command

Re: IDE + CPU Scaling problem on Via EPIA systems

[Dave Jones]

On Mon, Nov 28, 2005 at 12:02:32AM -0500, gboyce wrote:
 > Folks,
 > 
 > While attempting to setup a new server using a Via EPIA-M motherboard 
 > (Nehemiah processor), I encountered a problem when I enabled CPU Frequency 
 > scaling via the powernowd daemon.
 > 
 > The system is using software RAID 1 on a pair of IDE drives.  Everything 
 > goes fine until powernowd is enabled.  At that point I get the following 
 > errors:
 > 
 > [4294871.703000] hda: dma_timer_expiry: dma status == 0x20
 > [4294871.703000] hda: DMA timeout retry
 > [4294871.703000] hda: timeout waiting for DMA
 > [4294871.703000] hda: status error: status=0x58 { DriveReady SeekComplete 
 > DataRequest }
 > [4294871.703000]
 > [4294871.703000] ide: failed opcode was: unknown
 > [4294871.703000] hda: drive not ready for command
 > [4294958.589000] hda: dma_timer_expiry: dma status == 0x20
 > [4294958.589000] hda: DMA timeout retry
 > [4294958.589000] hda: timeout waiting for DMA
 > [4294958.589000] hda: status error: status=0x58 { DriveReady SeekComplete 
 > DataRequest }
 > [4294958.589000]
 > [4294958.589000] ide: failed opcode was: unknown
 > [4294958.589000] hda: drive not ready for command
 > 
 > I ran the system for an extended time previously with no problem, but at 
 > this point I did not use powernowd, and I was not using RAID.
 > 
 > The system is running Ubuntu, but I also encountered someone else with the 
 > same problem on an older Via EPIA system and SuSE.  The ubuntu kernel I'm 
 > using is 2.6.12-10-386.
 > 
 > I've attached the full dmesg output as well.
 > 
 > For now I'm just going to turn off cpu scaling.  Someday I'd like to use 
 > it though.  Any suggestions for things I can try?  Or is this perhaps a 
 > known issue of some sort?

On some variants of the VIA C3, we need to quiesce all DMA operations
before we do a speed transition. We currently don't do that.
I do have a patch from someone which adds support in the longhaul
driver to wait for IDE transactions to stop, but to do it cleanly,
we really need some callbacks into the IDE layer.

The longhaul driver right now is pretty much a case of
"if it works for you great, if not, don't use it".

		Dave

Re: IDE + CPU Scaling problem on Via EPIA systems

[Alan Cox]

On Llu, 2005-11-28 at 01:32 -0500, Dave Jones wrote:
> On some variants of the VIA C3, we need to quiesce all DMA operations
> before we do a speed transition. We currently don't do that.
> I do have a patch from someone which adds support in the longhaul
> driver to wait for IDE transactions to stop, but to do it cleanly,
> we really need some callbacks into the IDE layer.

I was under the impression you could turn the IO/MEM enable on the root
bridge off momentarily to get the needed DMA pause safely ? Or does it
abort rather than retry at that point ?

Re: IDE + CPU Scaling problem on Via EPIA systems

[Dave Jones]

On Sun, Dec 04, 2005 at 04:22:03PM +0000, Alan Cox wrote:
 > On Llu, 2005-11-28 at 01:32 -0500, Dave Jones wrote:
 > > On some variants of the VIA C3, we need to quiesce all DMA operations
 > > before we do a speed transition. We currently don't do that.
 > > I do have a patch from someone which adds support in the longhaul
 > > driver to wait for IDE transactions to stop, but to do it cleanly,
 > > we really need some callbacks into the IDE layer.
 > 
 > I was under the impression you could turn the IO/MEM enable on the root
 > bridge off momentarily to get the needed DMA pause safely ? Or does it
 > abort rather than retry at that point ?

I haven't tried that. Is that a safe thing to do ?
We do now disable mastering on all pci devices around the transition
as mandated in the spec, but that didn't really do much either.

Here's the patch I got from one user, which 'worked'...


Subject: [CPUFREQ] longhaul - avoid ide timeouts when bus mastering is off.

I really don't like this. Really.
Unfortunatly its necessary, otherwise after the transition, we live
for just a few minutes, and then just lockup.  In an ideal world,
the pm layer would allow some means of walking the device tree
quiescing DMA. Sadly, we don't live in an ideal world.

I'm open to suggestions on better ways to do this, as I'd rather
not push this to Linus' tree.

>From patch by: Ken Staton <ken_staton@agilent.com>
Signed-off-by: Dave Jones <davej@redhat.com>

--- linux-2.6.11/arch/i386/kernel/cpu/cpufreq/longhaul.c~	2005-05-24 01:51:51.000000000 -0400
+++ linux-2.6.11/arch/i386/kernel/cpu/cpufreq/longhaul.c	2005-05-24 01:52:07.000000000 -0400
@@ -30,6 +30,8 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/pci.h>
+#include <linux/ide.h>
+#include <linux/delay.h>
 
 #include <asm/msr.h>
 #include <asm/timex.h>
@@ -91,6 +91,25 @@ static char *print_speed(int speed)
 }
 #endif
 
+static void ide_idle(void)
+ {
+	int i;
+	ide_hwif_t *hwif = ide_hwifs;
+	ide_drive_t *drive;
+
+	i = 0;
+	do {
+		drive = &hwif->drives[i];
+		i++;
+		if (strncmp(drive->name,"hd",2) == 0) {
+			while (drive->waiting_for_dma)
+			udelay(10);
+		} else {
+			i = 0;
+		}
+	} while (i != 0);
+}	
+
 
 static unsigned int calc_speed(int mult)
 {
@@ -146,6 +165,7 @@ static void do_powersaver(union msr_long
 	longhaul->bits.RevisionKey = 0;
 
 	preempt_disable();
+	ide_idle();	/* avoid ide timeouts when bus master off */
 	local_irq_save(flags);
 
 	/*

Whilst it may work fine, and 99.9% of VIA systems are likely IDE, it does
nothing about SCSI, so it's not quite perfect.

That said, even a 99% coverage is better than a 0% coverage we currently have.

It also seems quite racy, as it does nothing to prevent new transactions
from beginning after the drive has become idle.

		Dave