On Thu, 2015-09-24 at 12:01 +0200, Hans de Goede wrote: > Hi, > > On 24-09-15 11:40, Ian Campbell wrote: > > On Wed, 2015-09-23 at 21:59 +0200, Hans de Goede wrote: > > > In recent allwinner kernel sources the mmc clk-delay settings have > > > been > > > slightly tweaked, and for sun9i they are completely different then > > > what > > > we are using. > > > > > > This commit brings us in sync with what allwinner does, fixing > > > problems > > > accessing sdcards on some A33 devices (and likely others). > > > > > > For pre sun9i hardware this makes the following changes: > > > -At 400Khz change the sample delay from 7 to 0 (first introduced in > > > A31 sdk) > > > > This one applied to sun9i as well as pre I think? > > > > > -At 50 Mhz change the sample delay from 5 to 4 (first introduced in > > > A23 sdk) > > > > By my reading it also changes oclk from 2 to 1 on <sun9i @ >50MHz. > > Right, I did not list that as we never do > 50MHz,
But the being changed here does handle that (the else hz > 50000000 case) and that is changing even if we somehow coincidentally arrange that this code is never used today I think it is worth mentioning so that if it does become used we have the history of when/why it was changed. > later on in the code > we've: > > cfg->f_max = 52000000; > > And that 52 is somewhat symbolically there, it is meant for 52MHz sdio > where as mmc / sdcards run at 50MHz max. Are these timings used for sdio as well then? That seems worth noting. > > > I don't really follow the a/w SDK stuff, is it the case that a given > > Ann > > SDK is tested and supported by Allwinner and used on real devices for > > processors Amm < Ann (chronologically, ? > > Yes and no, Allwinner used to have separate kernel sources for each > die, so one for sun4i, sun5i, sun6i and sun7i. > > Recently they have changed to one unified kernel tree though, so all > of sun6i, sun8i and sun9i build from the same kernel tree. Note that > sun7i is missing from the list. > > > IOW if a change was introduced in the A31 SDK do we then have > > confidence > > that it doesn't break A20 due to Allwinners (and their customer's) use > > of > > the A31 SDK on A20 or are we relying on our own + community testing? > > It is safe to assume that the A23 changes do not break on the A31 since > that is using the same kernel sources. The changes may cause issues > on A20 though (A10 / A13 do not use the sample delay bits of the register > AFAICT). So I've run several tests on A20 and things seem to work fine > with the new settings there. Great. > I believe that the mmc controller and the mmc clock bits really are the > same over all of A20 / A23 / A31 / A33, and that these new tweaked values > are better to use everywhere. > > Regards, > > Hans > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
