Re: Re: libata / IDE cs5536: 80c cable detect issue (and worse?)

Andreas Mohr
2013-07-19T12:26:56Z

On Fri, Jul 19, 2013 at 12:40:38PM +0200, Bartlomiej Zolnierkiewicz wrote:
>
> Hi,
>
> On Thursday, July 18, 2013 08:25:41 PM Andreas Mohr wrote:
> > Hi,
> >
> > forgot to mention that I had already added a libata.force=40c boot
> > after my 80c config issue discovery
> > which did successfully cause the "limiting to UDMA/33 due to 40c foo" dmesg
> > yet where there's now initial but strong confirmation via reports
> > that the resulting UDMA/33 limit did NOT manage to fix corruption issues,
> > thus it's more strongly likely that the "bound to ill-suited pata_amd driver"
> > (due to incorrectly configuring speeds, or due to not configuring speeds
> > at all due to possibly BIOS not providing emulation of PCI register accesses
> > to Geode bus, which would be properly supported by pata_cs5536 OTOH)
> > thing is the actual reason and might fix it (fingers crossed).
>
> UDMA/66 (and higher) requires 80-wire cable to work (if the vendor states
> that UDMA/66 is supported then UDMA/100 should also work on CS5536). UDMA/33
> should work just fine with 40-wire cable. Therefore this indeed sounds more
> like wrong driver being selected issue than a cable problem.

Hohumm, news flash:

We just found out that such image corruption
(not sure yet whether it's an *identical* case of corruption though)
also can occur when having the CF image written by a premium USB combo writer
on a *completely different machine* (should have done that counter check
somewhat earlier, sorry...).
IOW, this quite likely frees the driver from being the culprit
for our specific case, i.e. we're likely talking about a stupid software issue.

BUT, I'm still suspecting that we have a severe case of having the wrong driver activated:

. lsmod:
sd_mod 25977 2
snd_cs5535audio 6485 0
ata_generic 2239 0
pata_cs5536 2294 0
pata_amd 6641 1
libata 117483 3 ata_generic,pata_cs5536,pata_amd
scsi_mod 106093 2 sd_mod,libata
cs5535_gpio 1756 0

Pray tell me, this does look like pata_cs5536 gets loaded
due to also containing the PCI ID, yet then fails to bind,
as opposed to pata_amd which does (reference count 1)?

We also tried the pata_cs5536.msr=1 boot parm:

[ 0.000000] Kernel command line: [..........] pata_cs5536.msr=1 libata.force=40c [............]

, and that did NOT cause the only recognizeable pata_cs5536-triggered
log message
printk(KERN_ERR DRV_NAME ": Using MSR regs instead of PCI\n");
to occur in dmesg, IOW this driver *is* inactive.

We only had a

[ 68.861778] pata_amd 0000:00:0f.2: version 0.4.1
[ 68.864570] scsi0 : pata_amd
[ 68.865240] scsi1 : pata_amd

So, AFAICS, this leaves us with up to three (perhaps four?) corrections
that one would want to have:

- remove the woefully improper (forgotten!?!) CS5536 ID from pata_amd
(this correction is what one would want to have, and this would work fine,
right? Famous last words...)

- do a cable correction patch for libata side (I do think that indicating
40c if even one device is 40c-only is the way to go [as long as libata
cannot handle per-device settings], for safety reasons,
and if so that's probably also preferrable to advertising an UNK value,
since UNK would skip towards device-side cable detection
which might be unreliable in case ATA ID values (i.e., ATA_ID_HW_CONFIG)
happen to be incorrect,
e.g. especially in the case of CF cards (OTOH it specifically looks
for a 0x2000 bit being *set* for 80c indication,
thus it should be reliable after all since you'd expect ignorant/older
devices to provide zeroed fields only...)

- and what about cable correction patch for IDE side? Since IDE layer
cable probing sequence algo appears to be different ("why??"),
this might require advertising a different cable flag

- perhaps pata_cs5536 DMI quirk for that board, in case UDMA/100
(BIOS reports cable 0x03 value i.e. both 80c) happens to be too fast,
but given the advanced state of our discussion (pata_cs5536 driver
even completely inactive!!) and the DMI recognition issues that I reported
(empty strings) I don't think that's relevant, at least not now

Thanks,

Andreas Mohr