Hi, according to my data sheets the K4B8G1646D is the DDR3L and the K4B8G1646Q isn't.
So please someone double-check before moving around chips&money.
So it is not the wrong chip but it might be too much noise on the data/clock/etc. which doubles for a dual-die/dual-chip-select chip. This gets better margin when increasing voltage levels.
Am 16.08.2017 um 09:32 schrieb Michael Mrozek EvilDragon@openpandora.org:
Okay... Now we have a bit of a problem.
Apparently,.as the memory was basically working but just freezing (we we thought was a software issue), we've ordered the memory already - we have 4000 of those chips in stock.
I'm now trying to find our whether we can exchange them (they're still untouched and sealed), but this might not work...
What downsides do we.have with DDR3 memory? How much more power.do http://power.do/ they consume? How much more.heat do they produce?
ignoring non-linear effects: (1.5V/1.35V)^2 = 1.23 i.e. 23% more.
Are there any other downsides?
A tiny one: we need separate DTB for 2GB and 4GB... But U-Boot can load the right one since we already have two different U-Boot binaries.
BR, Nikolaus
On August 16, 2017 2:29:37 AM GMT+02:00, Michael Mrozek EvilDragon@openpandora.org wrote: On Di, 2017-08-15 at 17:00 -0700, Tony Lindgren wrote:
I just checked the part number on the 4GB RAM chips - and indeed, it is the K4B8G1646D, which means we have the DDR3 and NOT the DDR3L version (which would be K4B8G1646Q).
That's the reason we need 1.5V here. So we got the wrong memory chips for our use case!
I'll check back with what we ordered and what we received.
- Tony Lindgren tony@atomide.com [170815 16:57]:
Somehow we need 1.50V for the 4GB DDR3 to work reliably. No idea so far why this is though.
And here's the related kernel dts change for 1.50V.
Tony
8< ----------------------- From tony Mon Sep 17 00:00:00 2001 From: Tony Lindgren tony@atomide.com Date: Tue, 15 Aug 2017 13:06:47 -0700 Subject: [PATCH] ARM: dts: Fix up DDR3 voltage for pyra 4G
Looks like we need 1.50V instead of 1.35V for pyra-4g DDR3 to work reliably. Note that this needs to match the voltage configured by the bootloader.
When testing memory with two instances of memtester 1900M for example, make sure ti-soc-thermal and thermal-generic-adc modules are loaded. You may also need to use a proper heat sink on the CPU board.
arch/arm/boot/dts/pyra-mainboard-v5.0.dtsi | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/arm/boot/dts/pyra-mainboard-v5.0.dtsi b/arch/arm/boot/dts/pyra-mainboard-v5.0.dtsi --- a/arch/arm/boot/dts/pyra-mainboard-v5.0.dtsi +++ b/arch/arm/boot/dts/pyra-mainboard-v5.0.dtsi @@ -816,6 +816,12 @@ vbus-supply = <&otg_reg>; };
+/* pyra-4g memory needs 1.50V instead of 1.35V somehow */ +&smps6_reg {
- regulator-min-microvolt = <1500000>;
- regulator-max-microvolt = <1500000>;
+};
&smps10_out1_reg { /* never turn on or it may burn the Palmas! */ status = "disabled"; -- Mit freundlichen Grüßen,
Michael Mrozek
OpenPandora GmbH Geschäftsführer: Michael Mrozek
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