From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8318EC2BABC for ; Tue, 7 Apr 2020 06:38:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6418C2072A for ; Tue, 7 Apr 2020 06:38:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727162AbgDGGiU (ORCPT ); Tue, 7 Apr 2020 02:38:20 -0400 Received: from mga06.intel.com ([134.134.136.31]:58680 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726030AbgDGGiU (ORCPT ); Tue, 7 Apr 2020 02:38:20 -0400 IronPort-SDR: 6fVd+Tl0D+VeHngz5oTZt6+b0RZiD0ns7uydhDeTmfsxCghyYua5vgt/la/xdhb7hz5dIgTUFa venK98bfLUfw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Apr 2020 23:38:19 -0700 IronPort-SDR: acXIqMHlC2Var749gsjCYLUDv65hiGtYDDjyccFn7fbSKcPf0wneY31yBcdySE4077Hxhhc6Bx awghGDehFkcg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,353,1580803200"; d="scan'208";a="296867632" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.87]) ([10.237.72.87]) by FMSMGA003.fm.intel.com with ESMTP; 06 Apr 2020 23:38:16 -0700 Subject: Re: [PATCH v4 1/3] mmc: host: Introduce the request_atomic() for the host To: Baolin Wang , ulf.hansson@linaro.org Cc: orsonzhai@gmail.com, zhang.lyra@gmail.com, arnd@arndb.de, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org References: <04c25ff9f9b17d41d734c498e4be61dee745bb30.1585896945.git.baolin.wang7@gmail.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: <5a55947b-e920-4515-49cf-163f6d539421@intel.com> Date: Tue, 7 Apr 2020 09:37:30 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <04c25ff9f9b17d41d734c498e4be61dee745bb30.1585896945.git.baolin.wang7@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/04/20 10:05 am, Baolin Wang wrote: > The SD host controller can process one request in the atomic context if > the card is nonremovable, which means we can submit next request in the > irq hard handler when using the MMC host software queue to reduce the > latency. Thus this patch adds a new API request_atomic() for the host > controller, as well as adding support for host software queue to submit > a request by the new request_atomic() API. > > Moreover there is an unusual case that the card is busy when trying to > send a command, and we can not polling the card status in interrupt > context by using request_atomic() to dispatch requests. Thus we should > queue a work to try again in the non-atomic context in case the host > releases the busy signal later. > > Suggested-by: Adrian Hunter > Signed-off-by: Baolin Wang One minor point below, otherwise: Acked-by: Adrian Hunter > --- > drivers/mmc/host/mmc_hsq.c | 29 ++++++++++++++++++++++++++++- > drivers/mmc/host/mmc_hsq.h | 1 + > include/linux/mmc/host.h | 3 +++ > 3 files changed, 32 insertions(+), 1 deletion(-) > > diff --git a/drivers/mmc/host/mmc_hsq.c b/drivers/mmc/host/mmc_hsq.c > index b90b2c9..a57f802 100644 > --- a/drivers/mmc/host/mmc_hsq.c > +++ b/drivers/mmc/host/mmc_hsq.c > @@ -16,11 +16,20 @@ > #define HSQ_NUM_SLOTS 64 > #define HSQ_INVALID_TAG HSQ_NUM_SLOTS > > +static void mmc_hsq_retry_handler(struct work_struct *work) > +{ > + struct mmc_hsq *hsq = container_of(work, struct mmc_hsq, retry_work); > + struct mmc_host *mmc = hsq->mmc; > + > + mmc->ops->request(mmc, hsq->mrq); > +} > + > static void mmc_hsq_pump_requests(struct mmc_hsq *hsq) > { > struct mmc_host *mmc = hsq->mmc; > struct hsq_slot *slot; > unsigned long flags; > + int ret = 0; > > spin_lock_irqsave(&hsq->lock, flags); > > @@ -42,7 +51,24 @@ static void mmc_hsq_pump_requests(struct mmc_hsq *hsq) > > spin_unlock_irqrestore(&hsq->lock, flags); > > - mmc->ops->request(mmc, hsq->mrq); > + if (mmc->ops->request_atomic) > + ret = mmc->ops->request_atomic(mmc, hsq->mrq); > + else > + mmc->ops->request(mmc, hsq->mrq); > + > + /* > + * If returning BUSY from request_atomic(), which means the card > + * may be busy now, and we should change to non-atomic context to > + * try again for this unusual case, to avoid time-consuming operations > + * in the atomic context. > + * > + * Note: we just give a warning for other error cases, since the host > + * driver will handle them. > + */ > + if (ret == -EBUSY) > + schedule_work(&hsq->retry_work); > + else > + WARN_ON_ONCE(ret && ret != -EBUSY); 'ret != -EBUSY' is redundant because it is always true in the 'else' clause. > } > > static void mmc_hsq_update_next_tag(struct mmc_hsq *hsq, int remains) > @@ -325,6 +351,7 @@ int mmc_hsq_init(struct mmc_hsq *hsq, struct mmc_host *mmc) > hsq->mmc->cqe_private = hsq; > mmc->cqe_ops = &mmc_hsq_ops; > > + INIT_WORK(&hsq->retry_work, mmc_hsq_retry_handler); > spin_lock_init(&hsq->lock); > init_waitqueue_head(&hsq->wait_queue); > > diff --git a/drivers/mmc/host/mmc_hsq.h b/drivers/mmc/host/mmc_hsq.h > index 18b9cf5..ffdd9cd 100644 > --- a/drivers/mmc/host/mmc_hsq.h > +++ b/drivers/mmc/host/mmc_hsq.h > @@ -12,6 +12,7 @@ struct mmc_hsq { > wait_queue_head_t wait_queue; > struct hsq_slot *slot; > spinlock_t lock; > + struct work_struct retry_work; > > int next_tag; > int num_slots; > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index c318fb5..d4a50e5d 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -92,6 +92,9 @@ struct mmc_host_ops { > int err); > void (*pre_req)(struct mmc_host *host, struct mmc_request *req); > void (*request)(struct mmc_host *host, struct mmc_request *req); > + /* Submit one request to host in atomic context. */ > + int (*request_atomic)(struct mmc_host *host, > + struct mmc_request *req); > > /* > * Avoid calling the next three functions too often or in a "fast >