Re: [PATCH v2.6.38-rc7] Revert "libata: ahci_start_engine compliant to AHCI spec"

[Jian Peng <jipeng2005@xxxxxxxxx>]

Hi, Rafael,

 

I am using Dell E6410 with same AHCI host controller as your system, but could not reproduce the bug you found out (using Ubuntu 11.04 and 2.6.39-rc6 kernel).

Do you know which config file I need change to perform this testing?

 

Thanks,

Jian

On Wed, May 18, 2011 at 2:25 PM, Jian Peng <jipeng2005@xxxxxxxxx> wrote:

Sure, Please try this. Thanks,

 

diff -Naur a/drivers/ata/libahci.c b/drivers/ata/libahci.c
--- a/drivers/ata/libahci.c 2011-05-18 14:23:36.564665643 -0700
+++ b/drivers/ata/libahci.c 2011-05-18 14:24:52.564614378 -0700
@@ -539,27 +539,6 @@

 {
  void __iomem *port_mmio = ahci_port_base(ap);
  u32 tmp;
- u8 status;
-
- status = readl(port_mmio + PORT_TFDATA) & 0xFF;
-
- /*
-  * At end of section 10.1 of AHCI spec (rev 1.3), it states
-  * Software shall not set PxCMD.ST to 1 until it is determined
-  * that a functoinal device is present on the port as determined by
-  * PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h
-  *

-  * Even though most AHCI host controllers work without this check,

-  * specific controller will fail under this condition
-  */
- if (status & (ATA_BUSY | ATA_DRQ))
-  return;
- else {
-  ahci_scr_read(&ap->link, SCR_STATUS, &tmp);
-
-  if ((tmp & 0xf) != 0x3)
-   return;
- }
 
  /* start DMA */
  tmp = readl(port_mmio + PORT_CMD);

@@ -1353,6 +1332,8 @@

 
  ahci_start_engine(ap);
 
+ msleep(5);

+
  if (online)

   *class = ahci_dev_classify(ap);

2011/5/18 Rafael J. Wysocki <rjw@xxxxxxx>

On Wednesday, May 18, 2011, Jian Peng wrote:
> Hi, Valdis/Rafael/Michael,
>
> Could you help me test the following change?
>
> After reverting 81ca7e4, add 5ms delay as follow since that seems also
> fixing the issue on my SATA host controller that requires 81ca7e4.
>
> In drivers/ata/libahci.c, inside ahci_hardreset() function,
>
>

> 1333 <http://lxr.linux.no/linux+*/drivers/ata/libahci.c#L1333>
> ahci_start_engine
> <http://lxr.linux.no/linux+*/+code=ahci_start_engine>(ap
> <http://lxr.linux.no/linux+*/+code=ap>);
>
>             msleep(5);1334
> <http://lxr.linux.no/linux+*/drivers/ata/libahci.c#L1334>1335
> <http://lxr.linux.no/linux+*/drivers/ata/libahci.c#L1335>        if
> (online <http://lxr.linux.no/linux+*/+code=online>)1336
> <http://lxr.linux.no/linux+*/drivers/ata/libahci.c#L1336>
>   *class <http://lxr.linux.no/linux+*/+code=class> = ahci_dev_classify
> <http://lxr.linux.no/linux+*/+code=ahci_dev_classify>(ap

> <http://lxr.linux.no/linux+*/+code=ap>);

>
> Since my host controller requires time to switch internal state to be ready.
> Please let me know your testing result.

Could you simply post a patch?

Rafael

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