[U-Boot-Users] IDE access swaps the bytes.

[U-Boot-Users] IDE access swaps the bytes.

[Helio Fujimoto]

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[U-Boot-Users] IDE access swaps the bytes.

[Travis B. Sawyer]

Helio Fujimoto wrote:

 >it is attached directly to the bus. There is an FPGA which is controls 
the
 >IDE interface. The IDE data bus [0-15] is connected to the MPC855T 
data bus [15-0].


Ah.  We also have CF direct to local bus....
Here's how we connected it so as to keep common code common:

PER_DATA8     <->   CF_DATA15
PER_DATA9     <->   CF_DATA14
PER_DATA10   <->   CF_DATA13
PER_DATA11   <->   CF_DATA12
PER_DATA12   <->   CF_DATA11
PER_DATA13   <->   CF_DATA10
PER_DATA14   <->   CF_DATA9
PER_DATA15   <->   CF_DATA8
PER_DATA0   <->   CF_DATA7
PER_DATA1   <->   CF_DATA6
PER_DATA2   <->   CF_DATA5
PER_DATA3   <->   CF_DATA4
PER_DATA4   <->   CF_DATA3
PER_DATA5   <->   CF_DATA2
PER_DATA6   <->   CF_DATA1
PER_DATA7   <->   CF_DATA0

Since you're running directly from 855T local bus and not from your fpga,
you're in for some rewiring.  If, however, your data lines run through 
your fpga,
you can simply reprogram the pins.

Good luck,

Travis
ps:  I just switched from Evolution to Thunderbird, I hope this is plain 
text only!

[U-Boot-Users] IDE access swaps the bytes.

[Helio Fujimoto]

Thanks. That's what I suspected.

My webmail sends HTML messages by default, and I keep forgetting to set up
"plain text". Sorry about that.

Regards,

Helio Fujimoto.

=====================
Helio Fujimoto wrote:

>it is attached directly to the bus. There is an FPGA which is controls
the
>IDE interface. The IDE data bus [0-15] is connected to the MPC855T
data bus [15-0].


Ah.  We also have CF direct to local bus....
Here's how we connected it so as to keep common code common:

PER_DATA8     <->   CF_DATA15
PER_DATA9     <->   CF_DATA14
PER_DATA10   <->   CF_DATA13
PER_DATA11   <->   CF_DATA12
PER_DATA12   <->   CF_DATA11
PER_DATA13   <->   CF_DATA10
PER_DATA14   <->   CF_DATA9
PER_DATA15   <->   CF_DATA8
PER_DATA0   <->   CF_DATA7
PER_DATA1   <->   CF_DATA6
PER_DATA2   <->   CF_DATA5
PER_DATA3   <->   CF_DATA4
PER_DATA4   <->   CF_DATA3
PER_DATA5   <->   CF_DATA2
PER_DATA6   <->   CF_DATA1
PER_DATA7   <->   CF_DATA0

Since you're running directly from 855T local bus and not from your fpga,
you're in for some rewiring.  If, however, your data lines run through
your fpga,
you can simply reprogram the pins.

Good luck,

Travis
ps:  I just switched from Evolution to Thunderbird, I hope this is plain
text only!

[U-Boot-Users] IDE access swaps the bytes.

[Helio Fujimoto]

Wolfgang,
Sorry, I didn't see that. I am resending it in plain text.

======
Hi, there,
I am using the u-boot with a MPC855T based board, and
I am trying to boot from a compact flash by using the diskboot command.
After debugging the code, I found out that the u-boot does
not detect a DOS partition in the compact flash because
the bytes are swapped when data is read from the IDE.
In the same way, when the IDE device information is
gotten, they are shown as if they are swapped two by
two.

As the processor is big-endian, I supposed the u-boot
would automatically fix this swapping problem, though I
could not understand how. The IDE interface is set in
the CPU to have "16-bit" access. I don't know if I should
set a "define" to fix this swapping problem, or if I should
change the code (cmd_ide.c, I guess) using #ifdef <my platform>.
Actually, the Compact flash data sheet specifies exactly that, for a big
endian processor I should swap data when accessing a content inside it
(because in the compact flash access the even address data is the least
significant byte), and to not swap when reading the identification, exactly
the opposite of what is done in the code (in my understanding, I could be
wrong...)
Could anyone please explain this to me?

Thanks,

Helio Fujimoto.

[U-Boot-Users] IDE access swaps the bytes.

[Wolfgang Denk]

In message <OF3F292F76.1C02E690-ON88256F5E.006658A6-88256F5E.006658AA@Cyclades.com> you wrote:
> 
> I am using the u-boot with a MPC855T based board, and
> I am trying to boot from a compact flash by using the diskboot command.

I'm sorry, but my crystal ball is in dire need of an ectoplasmic  up-
grade  - in it's current state I am unable to see how your CF card is
attached to the system - is it  through  the  PCMCIA  controller,  or
directly on the bus, or what?

> After debugging the code, I found out that the u-boot does
> not detect a DOS partition in the compact flash because
> the bytes are swapped when data is read from the IDE.

This is something that is specific to your hardware, then.  It  works
fine on the systems we have here.

> As the processor is big-endian, I supposed the u-boot
> would automatically fix this swapping problem, though I
> could not understand how. The IDE interface is set in

By use of appropriate access macros?

> set a "define" to fix this swapping problem, or if I should
> change the code (cmd_ide.c, I guess) using #ifdef <my platform>.

Don't change the code as long as you don't  understand  what's  going
on.  As mentioned before: the current code is working fine on several
systems with both big- and little-endian architectures.

> Could anyone please explain this to me?

Without studying the schematics of your board? That's not  exactly  a
one-banana problem...

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Without facts, the decision cannot be made logically. You  must  rely
on your human intuition.
	-- Spock, "Assignment: Earth", stardate unknown

[U-Boot-Users] IDE access swaps the bytes

[Helio Fujimoto]

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[U-Boot-Users] IDE access swaps the bytes

[Wolfgang Denk]

In message <OF51AF3CF8.D4D195DC-ON88256F5E.005E7CA5-88256F5E.005E7CA8@Cyclades.com> you wrote:
> <FONT face=3D"Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size=
> =3D2><div><TABLE cellPadding=3D0 width=3D"100%">    <TR>    <TD colSpan=3D2=
> >      <P>Hi, there,</P>      <P>&nbsp;</P></TD></TR>  <FORM action=3D/trac=
> ker/index.php method=3Dpost>  <TR>    <TD colSpan=3D2>      <P>I am using t=
> he u-boot with a MPC855T based board, and <BR>I am trying       to boot fro=
> m a compact flash by using the diskboot command. After       debugging the =
> code, I found out that the u-boot does <BR>not detect a DOS       partition=
...


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