On 08/01/2014 20:13, Jason Gunthorpe wrote:
On Wed, Jan 08, 2014 at 08:00:02PM +0100, boris brezillon wrote:
Hello Jason,
Le 08/01/2014 19:34, Jason Gunthorpe a ?crit :
On Wed, Jan 08, 2014 at 03:21:58PM +0100, Boris BREZILLON wrote:
+int of_get_nand_timings(struct device_node *np, struct nand_timings *timings)
+{
+ memset(timings, 0, sizeof(*timings));
+ of_property_read_u32(np, "tCLS-min", &timings->tCLS_min);
+ of_property_read_u32(np, "tCLH-min", &timings->tCLH_min);
+ of_property_read_u32(np, "tCS-min", &timings->tCS_min);
[..]
A while ago when discussing another controller it was pointed out
these values are all auto-probable directly from the NAND via a ONFI
defined GET FEATURE @0x01 query, and adding these timings to the DT
was NAK'd..
Basically you set the interface to the slowest ONFI timing mode, do
the GET FEATURE to the NAND chip and then increase the interface speed
to the highest mutually supported ONFI mode.
Is there some reason you need to encode this in the DT?
What if the NAND does not support the ONFI interface (and this is
exactly the case for the NAND available on the cubietruck board:
H27UCG8T2ATR).
Sounds like a good reason to me!
You might want to check if you can boil down the DT timings from the
huge list to just an ONFI mode number..
Sure, but the sunxi driver needs at least 19 of them...
I'd echo Rob's comments, the property needs to include the units
in the name, and I strongly recommend picoseconds for these
values.
Agreed, picosecond is a more future-proof unit.
Also, you might want to check that the ONFI names for these parameters
are used, not a vendor specific name to try and avoid confusion.
I'll check it.
Thanks.
Best Regards,
Boris
Jason
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