linux-kernel - Re: How to disable DMA for compact-flash disk?

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Date:	Fri, 14 Aug 2009 14:51:27 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: How to disable DMA for compact-flash disk?

On 08/14/2009 02:32 PM, Alan Cox wrote:
>> Can you give me a clue as to what code needs poking?  I'm working
>> on the latest 31-rc5 tree, btw.
>>
>>
>> PS.  Can't get an ide based 2.6.31-rc5 kernel to boot in F11, though it doesn't seem
>> to be related to ide.  I probably have something wrong in my .config.
>
> Tejun made it all very class based so you have inheriting operations
> structures thus in pata_via.c find
>
> static struct ata_port_operations via_port_ops = {
>          .inherits       =&ata_bmdma_port_ops,
>
> and change it to
>
> static struct ata_port_operations via_port_ops = {
>          .inherits       =&ata_bmdma32_port_ops,
> --


I can't see that it made any difference:

pata_via 0000:00:0f.1: version 0.3.4
pata_via 0000:00:0f.1: PCI->APIC IRQ transform: INT A -> IRQ 20
scsi0 : pata_via
scsi1 : pata_via
ata1: PATA max UDMA/133 cmd 0x1f0 ctl 0x3f6 bmdma 0xe900 irq 14
ata2: PATA max UDMA/133 cmd 0x170 ctl 0x376 bmdma 0xe908 irq 15
ata1.01: CFA: Ridata CF, 20080820, max UDMA/133
ata1.01: 15662304 sectors, multi 0: LBA
ata1.01: limited to UDMA/33 due to 40-wire cable
ata1.01: configured for PIO4
scsi 0:0:1:0: Direct-Access     ATA      Ridata CF        2008 PQ: 0 ANSI: 5
sd 0:0:1:0: [sda] 15662304 512-byte logical blocks: (8.01 GB/7.46 GiB)
sd 0:0:1:0: [sda] Write Protect is off
sd 0:0:1:0: [sda] Mode Sense: 00 3a 00 00
sd 0:0:1:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
  sda:
sd 0:0:1:0: Attached scsi generic sg0 type 0
  sda1
sd 0:0:1:0: [sda] Attached SCSI disk

[root@...forge-D0-20 lanforge]# hdparm /dev/sda1

/dev/sda1:
  IO_support    =  0 (default)
  readonly      =  0 (off)
  readahead     = 256 (on)
  geometry      = 974/255/63, sectors = 14336000, start = 63


(read speed is still just under 3MB/s)


I used this patch:


diff --git a/drivers/ata/pata_via.c b/drivers/ata/pata_via.c
index 45657ca..0a1a3c9 100644
--- a/drivers/ata/pata_via.c
+++ b/drivers/ata/pata_via.c
@@ -420,7 +420,7 @@ static struct scsi_host_template via_sht = {
  };

  static struct ata_port_operations via_port_ops = {
-       .inherits       = &ata_bmdma_port_ops,
+       .inherits       = &ata_bmdma32_port_ops,
         .cable_detect   = via_cable_detect,
         .set_piomode    = via_set_piomode,
         .set_dmamode    = via_set_dmamode,
diff --git a/drivers/ata/sata_via.c b/drivers/ata/sata_via.c
index bdd43c7..0085d4a 100644
--- a/drivers/ata/sata_via.c
+++ b/drivers/ata/sata_via.c
@@ -114,7 +114,7 @@ static struct scsi_host_template svia_sht = {
  };

  static struct ata_port_operations svia_base_ops = {
-       .inherits               = &ata_bmdma_port_ops,
+       .inherits               = &ata_bmdma32_port_ops,
         .sff_tf_load            = svia_tf_load,
  };


Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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