On 8/20/26 8:34 AM, Frieder Schrempf wrote:
On 19.08.26 14:47, Marek Vasut wrote:
On 8/19/26 12:10 PM, Frieder Schrempf wrote:
On 19.08.26 12:04, Marek Vasut wrote:
On 8/19/26 9:07 AM, Frieder Schrempf wrote:
From: Frieder Schrempf <[email protected]>
In some cases we need to call ddr_init() multiple times to try
different configurations.
What different configurations ? Details please ?
The detection of different DDR types/sizes on our SoMs has always been
based on trying the init and seeing if it succeeds, falling back to the
smaller sizes on failure. See here [1].
Could you maybe bring the interface up in some minimal 400 MTps or 100
MTps configuration and then read out the MR ID registers from the DRAM
to discern which DRAM configuration is present on your SoM? This would
be the ideal generic way of doing this, and it would be reliable since
the IDs are stable and surely indicate which DRAM chip and how big it is.
No, unfortunately this doesn't work. We already tried. The MR ID can't
be used as we have single and dual rank setups that report the same ID.
We have no way of knowing how many dies are connected unless we try it.
Is the controller unable to interact with each rank separately ? I would
expect in single rank setup, that read of MR ID from one rank would pass
and from the other rank it would fail ?
