Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755500AbbHLMfl (ORCPT ); Wed, 12 Aug 2015 08:35:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39666 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751976AbbHLMfg (ORCPT ); Wed, 12 Aug 2015 08:35:36 -0400 Subject: Re: [linux-sunxi] [PATCH 3/3] mmc: sunxi: use controller automatic clock gating. To: hramrach@gmail.com, linux-sunxi@googlegroups.com, Seungwon Jeon , Jaehoon Chung , Ulf Hansson , Maxime Ripard , =?UTF-8?Q?David_Lanzend=c3=b6rfer?= , Chen-Yu Tsai , Arnd Bergmann , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: From: Hans de Goede Message-ID: <55CB3D92.6040403@redhat.com> Date: Wed, 12 Aug 2015 14:35:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1748 Lines: 58 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); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/