[U-Boot] [PATCH] sunxi: improve throughput in the sunxi_mmc driver

Maxime Ripard
2018-04-06T05:54:47Z

Hi Jaehoon,

On Wed, Mar 21, 2018 at 12:18:58PM +0100, Maxime Ripard wrote:
> From: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>
> Throughput tests have shown the sunxi_mmc driver to take over 10s to
> read 10MB from a fast eMMC device due to excessive delays in polling
> loops.
>
> This commit restructures the main polling loops to use get_timer(...)
> to determine whether a (millisecond) timeout has expired. We choose
> not to use the wait_bit function, as we don't need interruptability
> with ctrl-c and have at least one case where two bits (one for an
> error condition and another one for completion) need to be read and
> using wait_bit would have not added to the clarity.
>
> The observed speedup in testing on a A31 is greater than 10x (e.g. a
> 10MB write decreases from 9.302s to 0.884s).
>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

Any chance we can merge this for the next release?

Thanks!
Maxime

--
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering