On 18 September 2017 at 02:45, Michael Mrozek EvilDragon@openpandora.org wrote:
Running with DLL off at that frequency is therefore waay outside JEDEC-specified territory.
Well, yes and no. JEDEC specifies in the documentation that the timings are different when DLL is off and also specifies that DLL should always been on.
So the timings specified by JEDEC are DLL On timings.
Well, yes and no. Most of the DDR3 spec assumes DLL-on timings, and DLL-off mode is optional, but they do specify *some* things for DLL-off mode to allow interoperability between applications that use DLL-off mode and memory that is specified to support it. JEDEC however only specifies DLL-off mode for frequency up to 125 MHz. Of course this doesn't mean that higher frequencies necessarily won't work, just that you can't rely on it.
Well, now I'm confused... I thought with DLL off it's running with 125MHz and with DLL on it's 532MHz?
No, tony just toggled the DLL-on/off bit. Running at a lower frequency would require all timings to be recalculated, and I'm not even sure EMIF supports running at such a low frequency.
I just checked: There ARE standard speed bins in the JEDEC document as well - but they are identical to the speed bins listed in the Samsung memory chip.
Yes, most of the datasheet is copied directly from the JEDEC spec. I'm pretty sure every ram manufacturer does that.
However, JEDEC has multiple timings for DDR3-1066 (E, F, G, F(Optional), and so on), which are all different.
There's no "and so on", DDR3-1066 only has E (CL=6), F (CL=7), and G (CL=8) as JEDEC-specified bins.
The timings are often also specified as 6-6-6 / 7-7-7 / 8-8-8, which refer to CL, nRCD and nRP. The three numbers are always the same for JEDEC-specified DDR3 bins.
The Samsung datasheet only has ONE DDR3-1066, which seems to be DDR3- 1066F.
Yes, memory is specified into one of these bins for each frequency it supports. For our memory that's the DDR3-1066F bin, which means it supports 7-7-7 timings (which we're using) and 8-8-8 timings.
Hm, but the battery chip ALSO seems to remember some stuff.
You can't boot with AC Adaptor only and without battery for the first time, but it seems it works when you have at least booted once with battery.
Various settings in the charger ic are changed from their default, and these will be retained as long as some form of power is available. This is also true for some palmas settings.
And I think you can even fully remove the power for a while and it keeps that setting for a few seconds.
It sounds plausible that it can survive a bit on capacitance alone, but no idea how long.
Could it be the PALMAS (or we?) do have some supercap included that keeps the settings for a few settings (so you can replace the battery, for example)?
Palmas has a supercap for some of its settings and for the RTC, indeed to allow you to replace the battery without losing those settings and date/time. It isn't enabled by default though, so whether it's being used or not depends on how palmas is being configured during boot. It probably also won't help the charger ic to retain its settings.
In any case, all of this is only relevant if you remove all sources of power (including battery), not merely power off.
Matthijs