Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965434AbdCXJZI (ORCPT ); Fri, 24 Mar 2017 05:25:08 -0400 Received: from mga03.intel.com ([134.134.136.65]:55903 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934157AbdCXJYu (ORCPT ); Fri, 24 Mar 2017 05:24:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.36,214,1486454400"; d="scan'208";a="1111725958" Subject: Re: [PATCH] mmc: core: Do not hold re-tuning during CMD6 commands To: Chaotian Jing References: <1490336341-22292-1-git-send-email-chaotian.jing@mediatek.com> <1490336341-22292-2-git-send-email-chaotian.jing@mediatek.com> <13a83728-0031-5683-c371-4b517df32299@intel.com> <1490344369.22814.10.camel@mhfsdcap03> Cc: Ulf Hansson , Matthias Brugger , Jaehoon Chung , Shawn Lin , Masahiro Yamada , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: <03d54000-9ced-1b31-df80-d254f02433db@intel.com> Date: Fri, 24 Mar 2017 11:19:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <1490344369.22814.10.camel@mhfsdcap03> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2758 Lines: 64 On 24/03/17 10:32, Chaotian Jing wrote: > On Fri, 2017-03-24 at 09:52 +0200, Adrian Hunter wrote: >> On 24/03/17 08:19, Chaotian Jing wrote: >>> this patch is refine for 'commit c6dbab9cb58f ("mmc: core: Hold re-tuning >>> during switch commands")' >>> Since it has 3 retries at max for CMD6, if the first CMD6 got CRC error, >>> then should do re-tune before the next CMD6 was sent. >>> >>> Signed-off-by: Chaotian Jing >>> --- >>> drivers/mmc/core/mmc_ops.c | 3 +-- >>> 1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c >>> index fe80f26..6931927 100644 >>> --- a/drivers/mmc/core/mmc_ops.c >>> +++ b/drivers/mmc/core/mmc_ops.c >>> @@ -534,8 +534,6 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value, >>> bool use_r1b_resp = use_busy_signal; >>> unsigned char old_timing = host->ios.timing; >>> >>> - mmc_retune_hold(host); >>> - >>> /* >>> * If the cmd timeout and the max_busy_timeout of the host are both >>> * specified, let's validate them. A failure means we need to prevent >>> @@ -567,6 +565,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value, >>> cmd.sanitize_busy = true; >>> >>> err = mmc_wait_for_cmd(host, &cmd, MMC_CMD_RETRIES); >>> + mmc_retune_hold(host); >> >> That is not how mmc_retune_hold() works, you need mmc_retune_hold_now() as >> it is here: >> >> https://marc.info/?l=linux-mmc&m=148940903816582 >> >> But using "retries" with commands that have busy-waiting on the data line >> doesn't make much sense anyway. Particularly with CRC errors, I would >> expect the card is actually busily doing the switch and we need only to wait >> for it. The same can be true for timeout errors. For some CMD6 we might >> need to send CMD12 if the card is busy after an error. I would prefer an >> explicit attempt at recovery from CMD6 errors. >> > > It's the host driver's responsibility to ensure card is not in busy > state before issue the next R1B command, or the MMC core layer needs do > extra check/waiting before issue a R1B command. Better to deal with cards stuck in busy from the places where busy-waiting is expected. > I think the purpose of "re-tune" is trying to cover particular case(eg. > voltage fluctuate or EMI or some glitch of host/device which caused CRC > error) No, re-tuning is to compensate for drift caused primarily by temperature change. > error) , but in such cases, too many cases are disable re-tune function > by mmc_retune_hold(), for example, in this case, if a response CRC error > got then we never have chance to recover it. then cause system cannot > access emmc or suspend/resume fail. Maybe you have a hardware problem.