Re: sata_sil boot problems with kernel 2.6.35 and current git

[Tejun Heo <tj@kernel.org>]

(cc's added)
Hello,

On 09/08/2010 08:26 PM, gianluca wrote:
> Today I tried  the kernel 2.6.35 in one of my boxes but I realized that the
> box doesn't detect my SATA HD anymore. The logs show that the driver sata_sil
> is correctly loaded. With 2.6.34 it worked fine.
> 
> So I tried to test the latest git to see if the issue was fixed, but that
> kernel exhibits the same behaviour. Then I looked at the linux-ide mailing list
> archives at http://marc.info/?t=128232284600001&r=1&w=2 and I found out that 
> the issue is known but not solved and since I could reliably reproduce the
> problen I started to bisect.
> 
> The logs of the bisection are attached. It pointed to the commit
> 978c066691a49a205673672a55685305663a2554 (  libata: Remove excess delay in the
> tf_load path ).
> 
> So I reverted that commit and got a bootable kernel again. I think this commit
> exposed a timing bug in the sata_sil driver.

I love you.  Thank you so much for bisecting it.  :-)

Can you please test whether the patch at the end of this message is
enough to fix the problem?

Alan, the above commit seems a bit dangerous as writes can be merged.
Also, ISTR delay requirements for PATA while loading registers.  Mark,
Sergei, what do you guys think?

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 030b1c4..6a43129 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -418,6 +418,7 @@ void ata_sff_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 		if (ioaddr->ctl_addr)
 			iowrite8(tf->ctl, ioaddr->ctl_addr);
 		ap->last_ctl = tf->ctl;
+		ap->ops->sff_check_status(ap);
 	}

 	if (is_addr && (tf->flags & ATA_TFLAG_LBA48)) {
@@ -453,6 +454,7 @@ void ata_sff_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 		iowrite8(tf->device, ioaddr->device_addr);
 		VPRINTK("device 0x%X\n", tf->device);
 	}
+	ap->ops->sff_check_status(ap);
 }
 EXPORT_SYMBOL_GPL(ata_sff_tf_load);