[PATCH 1/3] Pyra/LC15: Workaround for 4GB DDR3 SMPS6 voltage

Michael Mrozek EvilDragon at openpandora.org
Wed Aug 16 02:29:37 CEST 2017


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 at 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 at 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

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