On 02/22/2011 07:01 PM, Damon Lynch wrote:
When using a Lexar ExpressCard CompactFlash (CF) reader in an ExpressCard slot, the speed of this high speed device is very slow (relatively speaking, of course).It performs at ~28MB/s instead of ~80MB/s it should be with a fast CompactFlash card. This is the product: http://www.lexar.com/products/lexar-professional-expresscard-compactflash-cf-reader?category=213 The CF card can run at UDMA/133, but is set to run at UDMA/33. $dmesg [ 1.687119] scsi0 : pata_jmicron [ 1.692480] scsi1 : pata_jmicron [ 1.692523] ata1: PATA max UDMA/100 cmd 0x4020 ctl 0x4014 bmdma 0x4000 irq 19 [ 1.692525] ata2: PATA max UDMA/100 cmd 0x4018 ctl 0x4010 bmdma 0x4008 irq 19 [ 1.870088] usb 1-6: new high speed USB device using ehci_hcd and address 3 [ 1.890676] ata1.00: CFA: TRANSCEND, 20091215, max UDMA/133 [ 1.890678] ata1.00: 125059072 sectors, multi 0: LBA [ 1.890681] ata1.00: limited to UDMA/33 due to 40-wire cable [ 1.930831] ata1.00: configured for UDMA/33 [ 1.930984] scsi 0:0:0:0: Direct-Access ATA TRANSCEND 2009 PQ: 0 ANSI: 5 [ 1.931132] sd 0:0:0:0: [sda] 125059072 512-byte logical blocks: (64.0 GB/59.6 GiB) [ 1.931144] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 1.931181] sd 0:0:0:0: [sda] Write Protect is off [ 1.931184] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 1.931371] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 1.932525] sda: sda1 [ 1.932904] sd 0:0:0:0: [sda] Attached SCSI disk
The CF adapter probably doesn't support the 80-wire cable detect protocol properly so the kernel thinks there's only a 40-wire cable connected to it. You can try libata.force=80c on the kernel command line and see what that does.
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