On Thu, Jan 19, 2012 at 12:56 PM, Aneesh V <aneesh@xxxxxx> wrote: > 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. Ah, sorry. Missed it in the chain of replies. > 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. Bummer. I'm guessing most applications where LPDDR* is used won't be suitable for modular memory, so there's not the same need for SPD. > 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. Are those properties of the memory, or a combination of memory and board properties? I think it still makes sense for the memories that do have it to use the SPD format and extend with additional properties, at least if it's only a few additional properties needed. > I don't see any option other than defining a new binding for LPDDR2. Yeah, agreed. -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
