From mboxrd@z Thu Jan 1 00:00:00 1970 From: hdegoede@redhat.com (Hans de Goede) Date: Wed, 12 Aug 2015 14:35:30 +0200 Subject: [linux-sunxi] [PATCH 3/3] mmc: sunxi: use controller automatic clock gating. In-Reply-To: References: Message-ID: <55CB3D92.6040403@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 In general this looks good, but I wonder how intensively this has been tested ? Also given the long latencies when using manual clock on/off support, have you done any testing to check what 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 ? Regards, Hans > --- > drivers/mmc/host/sunxi-mmc.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c > index f808a02..443cab5 100644 > --- a/drivers/mmc/host/sunxi-mmc.c > +++ b/drivers/mmc/host/sunxi-mmc.c > @@ -601,8 +601,13 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en) > rval = mmc_readl(host, REG_CLKCR); > rval &= ~(SDXC_CARD_CLOCK_ON | SDXC_LOW_POWER_ON); > > - if (oclk_en) > + if (oclk_en) { > rval |= SDXC_CARD_CLOCK_ON; > + if (!host->mmc->card || > + !(host->mmc->card->quirks & MMC_QUIRK_BROKEN_CLK_GATING)) > + > + rval |= SDXC_LOW_POWER_ON; > + } > > start = jiffies; > end = start + msecs_to_jiffies(750); >