From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seungwon Jeon Subject: RE: Cache Control during mmc_suspend_host Date: Fri, 16 Dec 2011 17:50:21 +0900 Message-ID: <002901ccbbcf$be9b3990$3bd1acb0$%jun@samsung.com> References: <000f01ccb960$42ac2a40$c8047ec0$%jun@samsung.com> <002f01ccba19$9c2bd9d0$d4838d70$%jun@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailout1.samsung.com ([203.254.224.24]:28005 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751924Ab1LPIuX convert rfc822-to-8bit (ORCPT ); Fri, 16 Dec 2011 03:50:23 -0500 Received: from epcpsbgm1.samsung.com (mailout1.samsung.com [203.254.224.24]) by mailout1.samsung.com (Oracle Communications Messaging Exchange Server 7u4-19.01 64bit (built Sep 7 2010)) with ESMTP id <0LWA003RSGJ9VFJ0@mailout1.samsung.com> for linux-mmc@vger.kernel.org; Fri, 16 Dec 2011 17:50:22 +0900 (KST) Received: from DOTGIHJUN01 ([12.23.118.161]) by mmp1.samsung.com (Oracle Communications Messaging Exchange Server 7u4-19.01 64bit (built Sep 7 2010)) with ESMTPA id <0LWA00D9WGJX8J80@mmp1.samsung.com> for linux-mmc@vger.kernel.org; Fri, 16 Dec 2011 17:50:21 +0900 (KST) In-reply-to: Content-language: ko Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: 'Saugata Das' Cc: linux-mmc@vger.kernel.org Saugata Das wrote: > On 14 December 2011 10:04, Seungwon Jeon wrote= : > > Saugata Das wrote: > >> On 13 December 2011 11:57, Seungwon Jeon wr= ote: > >> > Hi Saugata, > >> > > >> > Saugata Das wrote: > >> >> Hi Seungwon Jeon > >> >> > >> >> I see a small issue with the implementation mmc_suspend_host, > >> >> > >> >> int mmc_suspend_host(struct mmc_host *host) > >> >> { > >> >> ..... > >> >> =A0 =A0 =A0 err =3D mmc_cache_ctrl(host, 0); > >> >> } > >> >> > >> >> So, within mmc_suspend_host we are disabling the cache. But I d= o not > >> >> see a corresponding enabling of cache within mmc_resume_host. I > >> >> suggest we have either enabling of cache within mmc_resume_host= or > >> >> within mmc_suspend_host, we replace mmc_cache_ctrl(host, 0) wit= h the > >> >> flush operation, mmc_flush_cache(host->card). > >> >> > >> > Currently, > >> > Cache is enabled in mmc_init_card() during mmc_resume_host(). > >> > > >> Thanks for your answer. > >> > >> If mmc_card_keep_power is TRUE, then do you know why from mmc_resu= me > >> we call mmc_init_card instead of just mmc_awake which should reduc= e > >> some latency of system wakeup ? > >> > > I didn't find that case of keeping the power > > during sleep in mmc unlike sdio. >=20 > I am talking about keeping VCCQ ON and switching OFF only VCC. This i= s > normally the SLEEP mode of eMMC, which provides quicker wakeup or > resume. Some platforms will like to have quicker resume and will like > to avoid doing a mmc_init_card during resume. If that happens, then > the cache control disabling from mmc_suspend_host will be a problem. > So, I suggest we change that to mmc_flush_cache which logically does > the same as you wanted but it is also future proof. Yes. Currently mmc can wake up from sleep state using only CMD0 in mmc_init_= card. If we separate the escape route from sleep state, it must be considered= =2E Thank you for suggestion. >=20 > > > >> > >> > Thanks, > >> > Seungwon Jeon. > >> >> > >> >> > >> >> Regards > >> >> Saugata > >> >> -- > >> >> To unsubscribe from this list: send the line "unsubscribe linux= -mmc" in > >> >> the body of a message to majordomo@vger.kernel.org > >> >> More majordomo info at =A0http://vger.kernel.org/majordomo-info= =2Ehtml > >> > > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-mm= c" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at =A0http://vger.kernel.org/majordomo-info.ht= ml > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" = in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html