From: Jeff Garzik <jeff@garzik.org>
To: Kalra Ashish-B00888 <ashish.kalra@freescale.com>
Cc: IDE/ATA development list <linux-ide@vger.kernel.org>
Subject: Re: PMP device port link speed issues
Date: Thu, 25 Oct 2007 06:25:51 -0400 [thread overview]
Message-ID: <47206F2F.4020206@garzik.org> (raw)
In-Reply-To: <2A6F278C5B66C4459AF4013E77A40CD301003114@zin33exm20.fsl.freescale.net>
Kalra Ashish-B00888 wrote:
> While testing the "sata_fsl" driver with a Sil3726 based PMP, we had a
> specific configuration where the host port to PMP link speed was
> 1.5Gbps, while the PMP has configured it's device port(s) link speed to
> 3Gbps. This configuration causes NCQ hangs on certain Seagate drives,
> probably because of the link speed difference between host and PMP
> device & PMP device ports and drives.
>
> Does it makes sense to limit the PMP device port link speeds to the host
> port link speed ?
>
> I believe currently sata_pmp_attach() is calling sata_link_init_spd()
> for each PMP device port and thus causing PMP device port link speeds
> being configured independent of host port link speed. Probably the PMP
> device port links should be limited to the host link speed.
Interesting question. I'm sure Tejun will chime in, but I'm wondering
if there is any real use -- even theoretical -- for running downstream
links faster than the host<->PMP link?
Jeff
next prev parent reply other threads:[~2007-10-25 10:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-25 10:18 PMP device port link speed issues Kalra Ashish-B00888
2007-10-25 10:25 ` Jeff Garzik [this message]
2007-10-26 2:45 ` Tejun Heo
2007-10-29 13:59 ` Kalra Ashish-B00888
2007-10-29 23:20 ` Tejun Heo
2007-10-30 3:58 ` Tejun Heo
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