From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH 2/2] mmc: dw_mmc: check card present before starting request Date: Fri, 27 May 2016 12:46:14 +0900 Message-ID: <5747C306.7030909@samsung.com> References: <1464318141-5360-1-git-send-email-shawn.lin@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout3.samsung.com ([203.254.224.33]:55729 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932194AbcE0DqQ (ORCPT ); Thu, 26 May 2016 23:46:16 -0400 In-reply-to: <1464318141-5360-1-git-send-email-shawn.lin@rock-chips.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Shawn Lin , Ulf Hansson Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Doug Anderson , linux-rockchip@lists.infradead.org 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. Instead, Can it locate before calling dw_mci_queue_request()? Anyway, it looks good to me. Best Regards, Jaehoon Chung >