[PATCH v2 3/3] ARM: shmobile: gose: Add QSPI device to DT

Geert Uytterhoeven geert at linux-m68k.org
Thu Nov 12 23:52:14 PST 2015

Hi Simon,

On Fri, Nov 13, 2015 at 1:51 AM, Simon Horman <horms at verge.net.au> wrote:
>> > Tested: Read /dev/mtd0 with 512K blocks at 1.7MB/s
>> That's slow: I get 6.7 MB/s on koelsch (69.9 Mbps for Quad Read according
>> to my in-kernel QSPI debug code). Is this with SYS-DMAC enabled?
> Yes it does seem very small.
> I think that the problem is that /dev/mtd0 is very small, only 262kB.
> And I do not see any interrupts for dma-controllers when reading from hit.

Performance suffers badly from using small block sizes, so that explains it.

> /dev/mdt1 is much later, 4.2MB.
> dd reads that at ~7MB/s using 512kB blocks.

That's better.



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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