From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH] [SCSI] LIBSAS: fix libsas link error issue Date: Wed, 15 Jun 2011 00:15:34 -0400 Message-ID: <4DF831E6.3050502@interlog.com> References: <1308064628-11826-1-git-send-email-yxlraid@gmail.com> <1308065367.2401.24.camel@mulgrave> Reply-To: dgilbert@interlog.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Xiangliang Yu Cc: James Bottomley , "yxlraid@gmail.com" , "jack_wang@usish.com" , "lucas.demarchi@profusion.mobi" , "maciej.trela@intel.com" , "dan.j.williams@intel.com" , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jacky Feng List-Id: linux-scsi@vger.kernel.org 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@gmail.com wrote: >>> From: Xiangliang Yu >>> >>> -- 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 >>> --- >>> 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(.max_linkrate, .max_linkrate) Doug Gilbert