Hi Olof,
On Friday 20 January 2012 01:01 AM, Olof Johansson wrote:
Hi,
Sorry for the delay in responding, I know you pinged me about it yesterday.
On Thu, Jan 19, 2012 at 6:31 AM, Aneesh V<aneesh@xxxxxx> wrote:
device tree bindings for LPDDR2 SDRAM memories compliant
to JESD209-2 standard.
The 'lpddr2' binding in-turn uses another binding 'lpddr2-timings'
for specifying the AC timing parameters of the memory device at
different speed-bins.
As I just commented on the thread with Mike, I think we would be
better off sticking to embedding a standard JEDEC SPD structure in the
device tree. It's not large (128-256 bytes depending on memory type),
and it's clearly defined and used all over the industry.
It also has the benefit of reusing parsing code if you ever end up
with a system that uses DIMMs for memory, thus needing to parse the
SPD on said modules.
I did mention in the previous thread why SPD doesn't work for us ([1]
and [2]). Let me repeat the key points here.
1. I couldn't find an SPD addendum for LPDDR2 from the JEDEC website.
2. This seems to indicate that SPD is not used for LPDDR2 devices.
3. I tried to see if I can fit the DDR3 or DDR2 SPD for our needs. But
some of the AC timing parameters needed by our controller are not
available in those layouts.
I don't see any option other than defining a new binding for LPDDR2.
br,
Aneesh
[1] http://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg61250.html
[2] http://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg60473.html
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