On 11-06-14 09:44 PM, Xiangliang Yu wrote:
Subject: Re: [PATCH] [SCSI] LIBSAS: fix libsas link error issue
On Tue, 2011-06-14 at 23:17 +0800, yxlraid@xxxxxxxxx wrote:
From: Xiangliang Yu<yuxiangl@xxxxxxxxxxx>
-- The value of child link rate should is minimum of link rate, or
command will fail if child link rate is bigger than parent link rate.
Signed-off-by: Xiangliang Yu<yuxiangl@xxxxxxxxxxx>
---
drivers/scsi/libsas/sas_expander.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 874e29d..6ccca09 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -638,7 +638,7 @@ static void sas_ex_get_linkrate(struct domain_device *parent,
sas_port_add_phy(port, phy->phy);
}
}
- child->linkrate = min(parent_phy->linkrate, child->max_linkrate);
+ child->linkrate = min(parent_phy->linkrate, child->min_linkrate);
This patch doesn't look right. It will clamp the phy to the minim
possible link rate.
Link negotiation should get the minimum.
spl2r01.pdf [Most recent SAS-3 draft for the protocol layers]
5.7.4.2.1 SAS speed negotiation sequence overview
"The SAS speed negotiation sequence establishes communications between
the two phys on a physical link at the highest possible transmission
rate."
That seems to suggest:
min(<one_end>.max_linkrate, <other_end>.max_linkrate)
Doug Gilbert
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