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

[Richard Weinberger <richard@nod.at>]

----- Ursprüngliche Mail -----
> ----- Ursprüngliche Mail -----
>> Von: "Christian Loehle" <CLoehle@hyperstone.com>
>>> Can it be that rcar-gen3-sdhi changes some timings after switching?
>>> Either in software or on hardware.
>> 
>> Neither should be aware of the notion of a boot or user area partition.
>> Anything below mmc/core isn't, if we exclude the boot operation which is read
>> only, so not applicable to your problem.
>> So also a
>> while true; do dd if=/dev/zero of=/dev/mmcblkXboot0 bs=128K status=progress;
>> done
>> gives you like ~50KB/s consistently?
> 
> Exactly.
> 
> On the other hand, the very same command on /dev/mmcblk1p13 gives me always
> between
> 17 and 20 MB/s.

I did further tracing and on Linux I see clearly that tmio_mmc_irq() always much
later when writing to the boot area.

Another idea, since u-boot does not really support interrupts it polls various
status bits to detect completion of commands and data transfers.
Crazy idea: Maybe u-boot writes are faster than they should because it polls not always the
right bits?

...or Linux is too conservative and it matters for the boot area.

Thanks,
//richard