From mboxrd@z Thu Jan  1 00:00:00 1970
From: Robert Hancock <hancockrwd@gmail.com>
Subject: Re: ExpressCard compact flash card very slow
Date: Tue, 22 Feb 2011 23:48:18 -0600
Message-ID: <4D649FA2.5010204@gmail.com>
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To: Damon Lynch <damonlynch@gmail.com>
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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.