linux-kernel - Re: Stop SSD from waiting for "Spinning up disk..."

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Date:	Wed, 24 Jun 2015 09:28:52 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Jeff Chua <jeff.chua.linux@...il.com>
Cc:	Martin Steigerwald <martin@...htvoll.de>,
	Andreas Mohr <andi@...as.de>,
	lkml <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@....de>
Subject: Re: Stop SSD from waiting for "Spinning up disk..."

On Thu, Jun 25, 2015 at 12:22:47AM +0800, Jeff Chua wrote:
> On Wed, Jun 24, 2015 at 2:55 AM, Martin Steigerwald <martin@...htvoll.de> wrote:
> > Am Dienstag, 23. Juni 2015, 20:26:12 schriebst Du:
> >> Hi,
> >
> > Hi,
> >
> >> [proper In-Reply-To trail missing since lkml.org now fails to provide it]
> > […]
> >> > Greg,
> >> >
> >> > SSD is coming mainstream and it doesn't make sense wasting time
> >> > spinning up "disk" ...
> >>
> >> ...which probably is not truly being achieved
> >> by providing a *custom* kernel parameter
> >> which does apply to only those disk instances
> >> which some users *specifically* care about.
> >>
> >> Some things come to mind:
> >>
> >> - at this scope, generally spoken
> >>   one shouldn't be concerned with whether "we are SSD",
> >>   but rather whether "we (do not) need spinup"
> >>   (which might apply to a ton of different SCSI-based storage devices,
> >>   even some SAN-based platter-based ones)
> >>   *This* is what this is about
> >>   (and this could then have been reflected in kernel parameter naming)
> > […]
> >> - the kernel must already have some mechanisms to discern between
> >> (non-)platters (e.g. perhaps for knowing whether to support SSD TRIM
> >> command)
> >
> > Yep, for the first SSD in this laptop:
> >
> > merkaba:/sys> cat
> > ./devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sda/queue/rotational
> > 0
> 
> 
> It seems "rotational" is not reporting the correct status on USB devices ...
> 
> # cat /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/block/sda/queue/rotational
> 0
> # cat sys/devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/host10/target10:0:0/10:0:0:0/block/sdb/queue/rotational
> 1
> 
> # dmesg
> scsi host11: uas
> scsi 10:0:0:0: Direct-Access     JMicron  Generic          0114 PQ: 0 ANSI: 6
> 
> # cat /sys/kernel/debug/usb/devices
> T:  Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  4 Spd=5000 MxCh= 0
> D:  Ver= 3.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 9 #Cfgs=  1
> P:  Vendor=152d ProdID=0567 Rev= 1.14
> S:  Manufacturer=JMicron
> S:  Product=USB to ATA/ATAPI Bridge
> S:  SerialNumber=3186E514500030
> C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=  8mA
> I:  If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=uas
> 
> 
> Both sda and sdb have the same SSD model.

That's a bug in your USB bridge chip, odds are it is not reporting the
value properly.  There's nothing the scsi core or USB stack can do about
this, sorry.  Please complain to the hardware manufacturer.

greg k-h
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