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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A1E4C433EF for ; Wed, 9 Feb 2022 22:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234823AbiBIWDW (ORCPT ); Wed, 9 Feb 2022 17:03:22 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:47754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235022AbiBIWDN (ORCPT ); Wed, 9 Feb 2022 17:03:13 -0500 Received: from mail-lf1-x12b.google.com (mail-lf1-x12b.google.com [IPv6:2a00:1450:4864:20::12b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B549E00E24E for ; Wed, 9 Feb 2022 14:03:14 -0800 (PST) Received: by mail-lf1-x12b.google.com with SMTP id i17so6788279lfg.11 for ; Wed, 09 Feb 2022 14:03:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=Itlsq3+hS5Y9iy3ygo9I7us+gV+aSgo7u4P79ICKVnY=; b=BxtvxGZwH9hhHiy8OqyqqNmLvOfu7ij2Mqnmp1/5TkvYA1LfHMseH8fEdM/KqWrykN Xm0Q88VB32Y9XlGI2Abv9KXlMdTaG38aIFCdiCuKZojEob2BNqc0PwmETvRdBGt18eNO YE2ukUodr4x8Krd0cGDZkTU1gsIkbZNtmCqMaBd3FAqf+BUmkEYElvzH6rLgbqXy/n8z t5sLgvnrGB4CX7TiB7d5NG++iEGROz5rrn7xBhS88wDTcJvPGjDeAfCHiPJ+FszE/K1i jBF5N31tpafZqL88FgpKmSEWb8qWkdE8RukMSS6pQoW7SgonlfQy6YPimpMCYckSiRVK XjNQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=Itlsq3+hS5Y9iy3ygo9I7us+gV+aSgo7u4P79ICKVnY=; b=yrFfGGtqHjnAI/d7ZYXOIePwAd8ro6XWuJU7LMx5cA6a4C8HaXpJrXCta3omaBBNQl tB739uW/5k1bTfCvbgCP0DP+Veem2t0YnDT2AztUfC0/8fwiZVvE4SVOtl58vNYJrmV2 PSJR5ZvcwabW2D7qHF6lS1pUZlB00MVDnfSx15xHtLrV5M2EehA8fP+5v/wxFR5my5Yy jo0iMLzwDDsrqBI9+TD6/eV8sbAOSQNYR2uwqPuBsAKHVF9l5op1rqlq1dvSq82Ljj9F zQZvvhXZunHcI/6WTnsx5oBYUKN8scS21PuF+gSBdFbc6UeTJZKjRGG/lGzdXO+He2Qy 4ieQ== X-Gm-Message-State: AOAM533EyJovkUK5rwIvfQjaNPilYcf7Vp3EvnHMR+NgnndC0LARncOz fyKOigDr5E73suuaNAhGzFLvUA== X-Google-Smtp-Source: ABdhPJxlN+/1YXu/VKKNfgOkXudTxUBopzACvjjI7nQLgtidHg+iQN17+32xjG9smnA2peFinqqZPQ== X-Received: by 2002:ac2:5185:: with SMTP id u5mr3138375lfi.589.1644444192609; Wed, 09 Feb 2022 14:03:12 -0800 (PST) Received: from [192.168.1.211] ([37.153.55.125]) by smtp.gmail.com with ESMTPSA id n9sm914012lft.2.2022.02.09.14.03.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Feb 2022 14:03:11 -0800 (PST) Message-ID: <346cb67b-a5bb-b4ad-a15d-d2cfc850ccf5@linaro.org> Date: Thu, 10 Feb 2022 01:03:11 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH v2 1/2] drm/msm/dsi: Remove spurious IRQF_ONESHOT flag Content-Language: en-GB To: Daniel Thompson , Rob Clark , Sean Paul , Abhinav Kumar Cc: David Airlie , Daniel Vetter , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20220201174734.196718-1-daniel.thompson@linaro.org> <20220201174734.196718-2-daniel.thompson@linaro.org> From: Dmitry Baryshkov In-Reply-To: <20220201174734.196718-2-daniel.thompson@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/02/2022 20:47, Daniel Thompson wrote: > Quoting the header comments, IRQF_ONESHOT is "Used by threaded interrupts > which need to keep the irq line disabled until the threaded handler has > been run.". When applied to an interrupt that doesn't request a threaded > irq then IRQF_ONESHOT has a lesser known (undocumented?) side effect, > which it to disable the forced threading of irqs (and for "normal" kernels > it is a nop). In this case I can find no evidence that suppressing forced > threading is intentional. Had it been intentional then a driver must adopt > the raw_spinlock API in order to avoid deadlocks on PREEMPT_RT kernels > (and avoid calling any kernel API that uses regular spinlocks). > > Fix this by removing the spurious additional flag. > > This change is required for my Snapdragon 7cx Gen2 tablet to boot-to-GUI > with PREEMPT_RT enabled. > > Signed-off-by: Daniel Thompson Reviewed-by: Dmitry Baryshkov > --- > drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c > index 6b3ced4aaaf5d..3a3f53f0c8ae1 100644 > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c > @@ -1877,7 +1877,7 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi) > > /* do not autoenable, will be enabled later */ > ret = devm_request_irq(&pdev->dev, msm_host->irq, dsi_host_irq, > - IRQF_TRIGGER_HIGH | IRQF_ONESHOT | IRQF_NO_AUTOEN, > + IRQF_TRIGGER_HIGH | IRQF_NO_AUTOEN, > "dsi_isr", msm_host); > if (ret < 0) { > dev_err(&pdev->dev, "failed to request IRQ%u: %d\n", -- With best wishes Dmitry