[Libre-soc-dev] HDMI, DVI, DisplayPort on SBC (like Raspberry Pi) and on BMC

Cole Poirier colepoirier at gmail.com
Tue Jan 26 19:54:15 GMT 2021

On Mon, Jan 25, 2021 at 10:57 AM Jacob Lifshay <programmerjake at gmail.com> wrote:
> On Mon, Jan 25, 2021, 10:23 Luke Kenneth Casson Leighton <lkcl at lkcl.net>
> wrote:
> > power draw and raw data bandwidth for 4k monitors is MENTAL.
> >
> yup, hence why we might recommend only using 1080p or 1440p for the 1x32
> DDR3/4.
> >
> > i found a datasheet online for DDR4 that estimated power consumption for
> > "high performance" (lots of FIFOs, 8x AXI4 Buses) DDR4 and it was ONE WATT.
> >
> > that's insane: it's 30% of the entire power budget for the entire SoC.

Here's my two cents on this. For the high-bandwidth low-latency
applications of video and 3d why don't we use on die (on package?, I'm
not familiar enough to know which) LPDDR4X (0.6V vs 1.1V for LPDDR4)
which is drastically lower power and much lower latency than off
external SDRAM. We then also have expandable/swappable regular ddr4
DIMMs but running at a much lower clock speed/data rate to provide
larger memory that's needed for general purpose use cases. Thoughts?
Reasons why this would be prohibitively x, y or z and therefore not a
good idea or a possible solution?


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