Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756594AbdCXIdL (ORCPT ); Fri, 24 Mar 2017 04:33:11 -0400 Received: from mailgw01.mediatek.com ([218.249.47.110]:45719 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1756376AbdCXIc6 (ORCPT ); Fri, 24 Mar 2017 04:32:58 -0400 Message-ID: <1490344369.22814.10.camel@mhfsdcap03> Subject: Re: [PATCH] mmc: core: Do not hold re-tuning during CMD6 commands From: Chaotian Jing To: Adrian Hunter CC: Ulf Hansson , Matthias Brugger , Jaehoon Chung , Shawn Lin , Masahiro Yamada , , , , , Date: Fri, 24 Mar 2017 16:32:49 +0800 In-Reply-To: <13a83728-0031-5683-c371-4b517df32299@intel.com> 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> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2471 Lines: 54 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. 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) , 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.