Hello.
On 15-05-2012 23:20, Andre Hedrick (anhedric) wrote:
Sergei,
Sorry wrong answer about broken devices, and if I had taken such short
cuts in the past, the strength of the cheap storage would not have been
there or present today in Linux.
Just because someone calls it broken, because they don't read "ALL" the
associated specification,
Name the part I didn't read please.
it means they don't understand what they don't know.
From your words so far it follows to me that you who don't understand.
So try again with all the information before the classic call if
"it is broken" because I can't or don't know how to fix.
Your fix is incorrect because it blindly assumes that device is CFA basing
on word 0 while these alternate values (044Ah and 0040h) also correspond to
hard disks. We can't make such decisions without consulting word 83 first
which clearly follows from CFA 4.0. And in second of the identify data dumps
you sent to me privately the device erroneously don't indicate CFA command set
support in word 83, that's why it's not detected as CF. I agree however, that
we shoiuld try and overcome this incompatibility by adding more heuristics but
not in this proposed simplistic form.
Cheers,
Andre
-----Original Message-----
From: Sergei Shtylyov [mailto:sshtylyov@xxxxxxxxxx]
Sent: Tuesday, May 15, 2012 4:37 AM
To: Andre Hedrick (anhedric)
Cc: jgarzik@xxxxxxxxx; linux-ide@xxxxxxxxxxxxxxx; lkml@xxxxxxxxxxxxxxx
Subject: Re: CFA 4.0 patch
Hello.
On 15-05-2012 8:57, Andre Hedrick (anhedric) wrote:
This is a missing part of the CFA 4.0 and above support.
6.2.1.6.1 Word 0: General Configuration
This field indicates the general characteristics of the device.
When Word 0 of the Identify drive information is 848Ah then the device
is a CompactFlash Storage Card and complies with the CFA specification
and CFA command set. It is recommended that PC Card modes of operation
report only the 848Ah value as they are always intended as removable
devices.
Bits 15-0: CF Standard Configuration Value
Word 0 is 848Ah. This is the recommended value of Word 0.
Some operating systems require Bit 6 of Word 0 to be set to 1
(Non-removable device) to use the card as the root storage device. The
Card must be the root storage device when a host completely replaces
conventional disk storage with a CompactFlash Card in True IDE mode.
To
support this requirement and provide capability for any future
removable
media Cards, alternate handling of Word 0 is permitted.
Bits 15-0: CF Preferred Alternate Configuration Values
044Ah: This is the alternate value of Word 0 turns on ATA device and
turns off Removable Media and Removable Device while preserving all
Retired bits in the word.
0040h: This is the alternate value of Word 0 turns on ATA device and
turns off Removable Media and Removable Device while zeroing all
Retired bits in the word
If you did read a bit further, you'd have seen:
Bit 15-12: Configuration Flag
If bits 15:12 are set to 8h then Word 0 shall be 848Ah.
If bits 15:12 are set to 0h then Bits 11:0 are set using the definitions
below
and the Card is
required to support for the CFA command set and report that in bit 2 of
Word 83.
Bit 15:12 values other than 8h and 0h are prohibited.
That's why our code does what it does, and not checks for the
alternate
values. If our check in word 83 fails, we therefore have a broken
device.
Cheers,
Andre
--------------------
The Linux X-ATA/SATA guy
--- linux-2.6.32.orig/include/linux/ata.h Mon May 14 15:48:24 2012
+++ linux-2.6.32/include/linux/ata.h Mon May 14 15:51:42 2012
@@ -819,6 +819,10 @@
{
if (id[ATA_ID_CONFIG] == 0x848A) /* Traditional CF */
return 1;
+ if (id[ATA_ID_CONFIG] == 0x044A) /* Alternative CF w/
removable turned off, preserving retired bits */
+ return 1;
+ if (id[ATA_ID_CONFIG] == 0x0040) /* Alternative CF w/
removable turned off, zeroing retired bits*/
+ return 1;
/*
* CF specs don't require specific value in the word 0 anymore
and yet
* they forbid to report the ATA version in the word 80 and
require the
MBR, Sergei
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