[U-Boot] Memory size detection on P1011

[U-Boot] Memory size detection on P1011

[Felix Radensky]

Hi,

I'm working on a custom board based on P1011.
There are 2 board flavours, with either 128MB or 256MB of soldered
DDR2 SDRAM. Having u-boot image per board works fine, but I'd like
to have a single image and use get_ram_size() to detect memory size
at runtime. So far I had no luck.

The only significant difference between memory devices on these boards
is the number of banks: 4 banks on 128MB board and 8 banks on 256MB
board.

The memory size detection logic is loosely based on the code in
boards/tqc/tqm85xx/sdram.c, but I use fsl_ddr_set_memctl_regs()
to configure DDR controller registers and enable the controller.
The sequence is:

1. Configure TLBs for 2GB DDR
2. Configure LAWs for 2GB DDR
3. Configure DDR controller registers and enable DDR controller,
     CS0_BNDS is set to 256MB.
4. Iterate over possible memory sizes starting from the largest.
     Each iteration configures CS0_CONFIG (sets number of banks, rows 
and columns)
     and runs get_ram_size()

What I observe on 128MB board, is that only 32KB of RAM is detected in 
both
first and second iteration. So it seems that setting number of banks 
to 8 on
4-bank devices is fatal, and cannot be changed even if CS0_CONFIG is 
modified.

I've tried to rerun DDR controller initialization sequence with new 
CS0_CONFIG
value, but that just hangs the board. I've also tried to disable DDR 
controller via
RORDEVDISR register and then enable it and reconfigure DDR. That also 
leads
to hang.

I hope Freescale gurus on the list can help me to find a solution.

Thanks in advance.

Felix.

[U-Boot] Memory size detection on P1011

[York Sun]

Felix,

On Thu, 2011-05-05 at 16:17 +0300, Felix Radensky wrote:
> Hi,
> 
> I'm working on a custom board based on P1011.
> There are 2 board flavours, with either 128MB or 256MB of soldered
> DDR2 SDRAM. Having u-boot image per board works fine, but I'd like
> to have a single image and use get_ram_size() to detect memory size
> at runtime. So far I had no luck.
> 
> The only significant difference between memory devices on these boards
> is the number of banks: 4 banks on 128MB board and 8 banks on 256MB
> board.
> 
> The memory size detection logic is loosely based on the code in
> boards/tqc/tqm85xx/sdram.c, but I use fsl_ddr_set_memctl_regs()
> to configure DDR controller registers and enable the controller.
> The sequence is:
> 
> 1. Configure TLBs for 2GB DDR
> 2. Configure LAWs for 2GB DDR
> 3. Configure DDR controller registers and enable DDR controller,
>      CS0_BNDS is set to 256MB.
> 4. Iterate over possible memory sizes starting from the largest.
>      Each iteration configures CS0_CONFIG (sets number of banks, rows 
> and columns)
>      and runs get_ram_size()
> 
> What I observe on 128MB board, is that only 32KB of RAM is detected in 
> both
> first and second iteration. So it seems that setting number of banks 
> to 8 on
> 4-bank devices is fatal, and cannot be changed even if CS0_CONFIG is 
> modified.
> 
> I've tried to rerun DDR controller initialization sequence with new 
> CS0_CONFIG
> value, but that just hangs the board. I've also tried to disable DDR 
> controller via
> RORDEVDISR register and then enable it and reconfigure DDR. That also 
> leads
> to hang.
> 
> I hope Freescale gurus on the list can help me to find a solution.
> 
> Thanks in advance.
> 

I don't think get_ram_size works for your case. If you want to test the
DDR to find the correct size, you have to initialize the DDR first. But
you cannot do this correctly without knowing the number of banks. You
may be able to blindly set the bank number and test the DDR to catch the
error if there is any, but you have to run this code somewhere else, for
example, in the flash (before relocation).

There might be another way. Do you have any board ID to distinguish
these two kinds?

York

[U-Boot] Memory size detection on P1011

[Felix Radensky]

Hi York,

On 05/05/2011 04:29 PM, York Sun wrote:
> Felix,
>
> On Thu, 2011-05-05 at 16:17 +0300, Felix Radensky wrote:
>> Hi,
>>
>> I'm working on a custom board based on P1011.
>> There are 2 board flavours, with either 128MB or 256MB of soldered
>> DDR2 SDRAM. Having u-boot image per board works fine, but I'd like
>> to have a single image and use get_ram_size() to detect memory size
>> at runtime. So far I had no luck.
>>
>> The only significant difference between memory devices on these boards
>> is the number of banks: 4 banks on 128MB board and 8 banks on 256MB
>> board.
>>
>> The memory size detection logic is loosely based on the code in
>> boards/tqc/tqm85xx/sdram.c, but I use fsl_ddr_set_memctl_regs()
>> to configure DDR controller registers and enable the controller.
>> The sequence is:
>>
>> 1. Configure TLBs for 2GB DDR
>> 2. Configure LAWs for 2GB DDR
>> 3. Configure DDR controller registers and enable DDR controller,
>>       CS0_BNDS is set to 256MB.
>> 4. Iterate over possible memory sizes starting from the largest.
>>       Each iteration configures CS0_CONFIG (sets number of banks, rows
>> and columns)
>>       and runs get_ram_size()
>>
>> What I observe on 128MB board, is that only 32KB of RAM is detected in
>> both
>> first and second iteration. So it seems that setting number of banks
>> to 8 on
>> 4-bank devices is fatal, and cannot be changed even if CS0_CONFIG is
>> modified.
>>
>> I've tried to rerun DDR controller initialization sequence with new
>> CS0_CONFIG
>> value, but that just hangs the board. I've also tried to disable DDR
>> controller via
>> RORDEVDISR register and then enable it and reconfigure DDR. That also
>> leads
>> to hang.
>>
>> I hope Freescale gurus on the list can help me to find a solution.
>>
>> Thanks in advance.
>>
> I don't think get_ram_size works for your case. If you want to test the
> DDR to find the correct size, you have to initialize the DDR first. But
> you cannot do this correctly without knowing the number of banks. You
> may be able to blindly set the bank number and test the DDR to catch the
> error if there is any, but you have to run this code somewhere else, for
> example, in the flash (before relocation).
>
> There might be another way. Do you have any board ID to distinguish
> these two kinds?
>
> York
>
>

Thanks a lot for a prompt reply, I appreciate it very much.

I suspected this might be the case. The tqm boards I've
used as a reference all have 4-bank memory devices, so
that's why it get_ram_size() works for them.

We'll have to keep board ID on EEPROM to distinguish
between boards with different RAM sizes.

Thanks a lot for your help.

Felix.

[U-Boot] Memory size detection on P1011

[Wolfgang Denk]

Dear York Sun,

In message <1304602168.21927.16.camel@oslab-l1> you wrote:
> 
> I don't think get_ram_size works for your case. If you want to test the

You are wrong. We have been doing this for a long time on many boards
with similar properties.

> DDR to find the correct size, you have to initialize the DDR first. But
> you cannot do this correctly without knowing the number of banks. You
> may be able to blindly set the bank number and test the DDR to catch the

Incorrect number of banks will give different results than correct
number, so try both. The correct configuration is simply the one that
gives the maximum total memory size.

> error if there is any, but you have to run this code somewhere else, for
> example, in the flash (before relocation).

Of course the RAM init code runs before relocation.

> There might be another way. Do you have any board ID to distinguish
> these two kinds?

The recommended way is to use get_ram_size().

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Overdrawn?  But I still have checks left!

[U-Boot] Memory size detection on P1011

[Felix Radensky]

Hi Wolfgang,

On 05/05/2011 09:24 PM, Wolfgang Denk wrote:
> Dear York Sun,
>
> In message<1304602168.21927.16.camel@oslab-l1>  you wrote:
>> I don't think get_ram_size works for your case. If you want to test the
> You are wrong. We have been doing this for a long time on many boards
> with similar properties.
>
>> DDR to find the correct size, you have to initialize the DDR first. But
>> you cannot do this correctly without knowing the number of banks. You
>> may be able to blindly set the bank number and test the DDR to catch the
> Incorrect number of banks will give different results than correct
> number, so try both. The correct configuration is simply the one that
> gives the maximum total memory size.

I'm trying to do that, but get the same wrong memory size
in both cases. On the other hand, if I program the correct
number of banks from the start, get_ram_size() returns the
correct size in both cases.

The closest example of using get_ram_size() I've found is
for MPC8548 TQM boards. But all these boards have 4-bank
memory devices, so I'm sure my case was tested. Don't you
think there can be a problem with reprogramming bank number
in this particular DDR controller ?

Felix.

[U-Boot] Memory size detection on P1011

[Wolfgang Denk]

Dear Felix Radensky,

In message <4DC2F72F.2050009@embedded-sol.com> you wrote:
> 
> The closest example of using get_ram_size() I've found is
> for MPC8548 TQM boards. But all these boards have 4-bank
> memory devices, so I'm sure my case was tested. Don't you
> think there can be a problem with reprogramming bank number
> in this particular DDR controller ?

I haven't done this myself yet on this hardware, but I would be very
surprised if you could not reprogram the controller.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
You might not be as stupid as you look. This is not hard. Let's think
about this. I mean ... I'll think about this, and  you  can  join  in
when you know the words.             - Terry Pratchett, _Men at Arms_

[U-Boot] Memory size detection on P1011

[Felix Radensky]

Hi York,

On 05/05/2011 10:43 PM, Wolfgang Denk wrote:
> Dear Felix Radensky,
>
> In message<4DC2F72F.2050009@embedded-sol.com>  you wrote:
>> The closest example of using get_ram_size() I've found is
>> for MPC8548 TQM boards. But all these boards have 4-bank
>> memory devices, so I'm sure my case was tested. Don't you
>> think there can be a problem with reprogramming bank number
>> in this particular DDR controller ?
> I haven't done this myself yet on this hardware, but I would be very
> surprised if you could not reprogram the controller.
>
>

Can you please clarify this for me. If I understand you correctly,
the number of banks cannot be changed after DDR controller was
initialized. Is my understanding correct ?

Thanks a lot.

Felix.