Re: Poor write performance to boot area using rcar-gen3-sdhi

[Richard Weinberger <richard@nod.at>]

----- Ursprüngliche Mail -----
> Von: "Christian Loehle" <CLoehle@hyperstone.com>
> Your eMMC likely treats the boot partitions differently than the user area, e.g.
> in regards to cache.
> Is this reproducible for more 4k writes? What about larger writes?

Yes. So far every write size I tried is slow.
Sometimes (1 out of 50) small writes are fast, that's most likely a caching effect
of eMMC internals.

> The eMMC might not even have the mapping available after boot and first has to
> internally switch to it, in contrast to at u-boot stage?

Wouldn't that explain only the first slow write?
I see poor write speed also on repeated runs.
 
> Anyway this is probably more a question to your eMMC manufacturer and nothing
> the host is to be blamed, as you mentioned yourself, the time is spent at
> CMD25.

The eMMC manufacturer says there is nothing special about the boot area
and write speed should be equally fast.

Can it be that rcar-gen3-sdhi changes some timings after switching?
Either in software or on hardware.

Thanks,
//richard