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=-12.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 025A0C072B5 for ; Fri, 24 May 2019 13:02:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C468F2133D for ; Fri, 24 May 2019 13:02:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=onstation.org header.i=@onstation.org header.b="smAVCUCy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391124AbfEXNCK (ORCPT ); Fri, 24 May 2019 09:02:10 -0400 Received: from onstation.org ([52.200.56.107]:54248 "EHLO onstation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391045AbfEXNCK (ORCPT ); Fri, 24 May 2019 09:02:10 -0400 Received: from localhost (c-98-239-145-235.hsd1.wv.comcast.net [98.239.145.235]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: masneyb) by onstation.org (Postfix) with ESMTPSA id B68C73E88C; Fri, 24 May 2019 13:02:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=onstation.org; s=default; t=1558702928; bh=z0jLt5GmPMP9SlehCoH5XOtq6l1p49diMIagJEvp4Qk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=smAVCUCykCHg++Dm5V8KlqfT5bsIWumj7ZrBGCUTy1m2iBlT5OcjhX8UojJtSkArp oO1iKMD08rTaMxV65tpG71BGKZI74eEZXsPUcu8XJmKDy+Un1OI9m7V5vCceJ9SDAz +SeCUTfxNxkazFQxBs6dIPwU4/AU/YhAZhx6naOQ= Date: Fri, 24 May 2019 09:02:08 -0400 From: Brian Masney To: Adrian Hunter Cc: ulf.hansson@linaro.org, faiz_abbas@ti.com, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH] mmc: sdhci: queue work after sdhci_defer_done() Message-ID: <20190524130208.GA16322@basecamp> References: <20190524111053.12228-1-masneyb@onstation.org> <70782901-a9ac-5647-1abe-89c86a44a01b@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <70782901-a9ac-5647-1abe-89c86a44a01b@intel.com> Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Fri, May 24, 2019 at 03:17:13PM +0300, Adrian Hunter wrote: > On 24/05/19 2:10 PM, Brian Masney wrote: > > WiFi stopped working on the LG Nexus 5 phone and the issue was bisected > > to the commit c07a48c26519 ("mmc: sdhci: Remove finish_tasklet") that > > moved from using a tasklet to a work queue. That patch also changed > > sdhci_irq() to return IRQ_WAKE_THREAD instead of finishing the work when > > sdhci_defer_done() is true. Change it to queue work to the complete work > > queue if sdhci_defer_done() is true so that the functionality is > > equilivent to what was there when the finish_tasklet was present. This > > corrects the WiFi breakage on the Nexus 5 phone. > > > > Signed-off-by: Brian Masney > > Fixes: c07a48c26519 ("mmc: sdhci: Remove finish_tasklet") > > --- > > See 'sdhci@f98a4900' in qcom-msm8974-lge-nexus5-hammerhead.dts for > > details about how the WiFi is wired into sdhci on this platform. > > > > bisect log: > > > > git bisect start > > # bad: [4dde821e4296e156d133b98ddc4c45861935a4fb] Merge tag 'xfs-5.2-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux > > git bisect bad 4dde821e4296e156d133b98ddc4c45861935a4fb > > # good: [e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd] Linux 5.1 > > git bisect good e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd > > # bad: [8c79f4cd441b27df6cadd11b70a50e06b3b3a2bf] Merge tag 'docs-5.2' of git://git.lwn.net/linux > > git bisect bad 8c79f4cd441b27df6cadd11b70a50e06b3b3a2bf > > # bad: [67a242223958d628f0ba33283668e3ddd192d057] Merge tag 'for-5.2/block-20190507' of git://git.kernel.dk/linux-block > > git bisect bad 67a242223958d628f0ba33283668e3ddd192d057 > > # good: [8ff468c29e9a9c3afe9152c10c7b141343270bf3] Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip > > git bisect good 8ff468c29e9a9c3afe9152c10c7b141343270bf3 > > # good: [e2a5be107f52cefb9010ccae6f569c3ddaa954cc] staging: kpc2000: kpc_spi: Fix build error for {read,write}q > > git bisect good e2a5be107f52cefb9010ccae6f569c3ddaa954cc > > # bad: [cf482a49af564a3044de3178ea28f10ad5921b38] Merge tag 'driver-core-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core > > git bisect bad cf482a49af564a3044de3178ea28f10ad5921b38 > > # good: [9f2e3a53f7ec9ef55e9d01bc29a6285d291c151e] Merge tag 'for-5.2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux > > git bisect good 9f2e3a53f7ec9ef55e9d01bc29a6285d291c151e > > # good: [b4b52b881cf08e13d110eac811d4becc0775abbf] Merge tag 'Wimplicit-fallthrough-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux > > git bisect good b4b52b881cf08e13d110eac811d4becc0775abbf > > # bad: [d5f758f2df8015b8dcf47b6403cc192e4cef734d] mmc: meson-gx: disable HS400 > > git bisect bad d5f758f2df8015b8dcf47b6403cc192e4cef734d > > # good: [b3fb9d64b497b890f7b779a9f0b40b5cc269ea18] mmc: mmci: define get_dctrl_cfg for legacy variant > > git bisect good b3fb9d64b497b890f7b779a9f0b40b5cc269ea18 > > # good: [ade024f130f742725da9219624b01666f04bc4a6] memstick: jmb38x_ms: remove set but not used variable 'data' > > git bisect good ade024f130f742725da9219624b01666f04bc4a6 > > # bad: [42c38d4a1bc41e78dedbf73b0fb35e44007789bb] mmc: core: Fix warning and undefined behavior in mmc voltage handling > > git bisect bad 42c38d4a1bc41e78dedbf73b0fb35e44007789bb > > # good: [19d2f695f4e82794df7465b029c02b104d1b9903] mmc: sdhci: Call mmc_request_done() from IRQ handler if possible > > git bisect good 19d2f695f4e82794df7465b029c02b104d1b9903 > > # bad: [71c733c4e1aeb83e8221e89caeec893d51f88b7b] mmc: tegra: add sdhci tegra suspend and resume > > git bisect bad 71c733c4e1aeb83e8221e89caeec893d51f88b7b > > # bad: [c07a48c2651965e84d35cf193dfc0e5f7892d612] mmc: sdhci: Remove finish_tasklet > > git bisect bad c07a48c2651965e84d35cf193dfc0e5f7892d612 > > # first bad commit: [c07a48c2651965e84d35cf193dfc0e5f7892d612] mmc: sdhci: Remove finish_tasklet > > > > drivers/mmc/host/sdhci.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c > > index 97158344b862..3563c3bc57c9 100644 > > --- a/drivers/mmc/host/sdhci.c > > +++ b/drivers/mmc/host/sdhci.c > > @@ -3115,7 +3115,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id) > > continue; > > > > if (sdhci_defer_done(host, mrq)) { > > - result = IRQ_WAKE_THREAD; > > + queue_work(host->complete_wq, &host->complete_work); > > The IRQ thread has a lot less latency than the work queue, which is why it > is done that way. > > I am not sure why you say this change is equivalent to what was there > before, nor why it fixes your problem. > > Can you explain some more? What I meant by the equivalent change was that tasklet_schedule() used to be called in this situation rather than returning IRQ_WAKE_THREAD. I'm honestly not sure exactly what's going on yet. Without the patch I sent out, wlan0 is not detected on the phone. Perhaps there is a subtle race condition somewhere that is exposed with the reduction in latency since I assume tasklet_schedule() is more expensive than doing the processing in the bottom half? I'll do some more digging and see if I can find more information. I sent this out to get a discussion started. Brian