Re: [linux-sunxi] [PATCH 3/3] mmc: sunxi: use controller automatic clock gating.

From: Michal Suchanek
Date: Wed Aug 12 2015 - 08:54:27 EST

On 12 August 2015 at 14:35, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> Hi,
> On 12-08-15 14:23, Michal Suchanek wrote:
>> When core does not set the MMC_QUIRK_BROKEN_CLK_GATING flag enable
>> automatic hardware controlled clock gating on the mmc interface.
>> Signed-off-by: Michal Suchanek <hramrach@xxxxxxxxx>
> In general this looks good, but I wonder how intensively this has
> been tested ?

Unlike the wrong timeout it does not cause the boards to crash frequently ;-)

It would be nice if somebody actively using some board atm tested this.

> Also given the long latencies when using manual
> clock on/off support, have you done any testing to check what

I suspect the long latency is due to the controller flushing data to
the card or something like that since it happens only under load.

> sort of latencies this adds, e.g. Both with and without
> the patch, dump all the filesystem caches:
> echo 3 > /proc/sys/vm/drop_caches
> And then do:
> time cat /some/small/file/on/the/sdcard
> Do this at least 3 time both with and without the patch, and see
> if there are any noticable differences ?

Yes, it would be good idea to test.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at