From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752393AbcE0EN3 (ORCPT ); Fri, 27 May 2016 00:13:29 -0400 Received: from lucky1.263xmail.com ([211.157.147.130]:59640 "EHLO lucky1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750766AbcE0EN2 (ORCPT ); Fri, 27 May 2016 00:13:28 -0400 X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 X-RL-SENDER: shawn.lin@rock-chips.com X-FST-TO: linux-rockchip@lists.infradead.org X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: shawn.lin@rock-chips.com X-UNIQUE-TAG: X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH 2/2] mmc: dw_mmc: check card present before starting request To: Jaehoon Chung , Ulf Hansson References: <1464318141-5360-1-git-send-email-shawn.lin@rock-chips.com> <5747C306.7030909@samsung.com> Cc: shawn.lin@rock-chips.com, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Doug Anderson , linux-rockchip@lists.infradead.org From: Shawn Lin Message-ID: Date: Fri, 27 May 2016 12:13:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <5747C306.7030909@samsung.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2016/5/27 11:46, Jaehoon Chung 写道: > Hi Shawn, > > On 05/27/2016 12:02 PM, Shawn Lin wrote: >> The main reason to add this check is to avoid unnecessary >> mmc_request like the on-going cmd and the corresponding sbc >> if the card is removed. Although we have already checked this in >> dw_mci_handle_cd for runtime usage of sd card and dw_mci_init_slot >> for noremovable devices, but there is a timing gap before it really >> calls dw_mci_get_cd as mmc_detect_change needs some delay here. >> >> Another gain here is that we could save some checkings of card status >> after sd card been removed. >> >> Signed-off-by: Shawn Lin >> --- >> >> drivers/mmc/host/dw_mmc.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index cb30e91..8eb7898 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -105,6 +105,7 @@ struct idmac_desc { >> static bool dw_mci_reset(struct dw_mci *host); >> static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset); >> static int dw_mci_card_busy(struct mmc_host *mmc); >> +static int dw_mci_get_cd(struct mmc_host *mmc); >> >> #if defined(CONFIG_DEBUG_FS) >> static int dw_mci_req_show(struct seq_file *s, void *v) >> @@ -1255,7 +1256,7 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq) >> */ >> spin_lock_bh(&host->lock); >> >> - if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) { >> + if (!dw_mci_get_cd(mmc)) { >> spin_unlock_bh(&host->lock); >> mrq->cmd->error = -ENOMEDIUM; >> mmc_request_done(mmc, mrq); > > I think spin_lock/unlock_bh() should be removed at here. yes, we should hole the lock before dw_mci_queue_request as dw_mci_get_cd release it, in which state we do the minmum changes for achieving what we need here. I will fix it. > Instead, Can it locate before calling dw_mci_queue_request()? > > Anyway, it looks good to me. > > Best Regards, > Jaehoon Chung > >> > > > > -- Best Regards Shawn Lin