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 3F5DFC71153 for ; Mon, 28 Aug 2023 17:16:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229618AbjH1RQH (ORCPT ); Mon, 28 Aug 2023 13:16:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229650AbjH1RPh (ORCPT ); Mon, 28 Aug 2023 13:15:37 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17A58A7; Mon, 28 Aug 2023 10:15:34 -0700 (PDT) Received: from pendragon.ideasonboard.com (117.145-247-81.adsl-dyn.isp.belgacom.be [81.247.145.117]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id F290C5AA; Mon, 28 Aug 2023 19:14:10 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1693242851; bh=9CcR3k+ZeoGhjHA5toY1lOOIlpjjD+5Lfe/6lzVQeHE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tLUQTTGF7w9btKRhO8eUPPdc4XjIc+UoZHKrLys93FItNwlwWpsP4oORW5RX0xph3 T2EV0r4tcg3k7eZt3sXgbn+VdIxeJXvX1XdGuJgrJKIFOCRa6meE52m8JqZVzLW3lX ubHhKfhWI+c/t+6UEV6b4aJUZtRdsvOeIFoOyjj8= Date: Mon, 28 Aug 2023 20:15:41 +0300 From: Laurent Pinchart To: Bryan O'Donoghue Cc: rfoss@kernel.org, todor.too@gmail.com, agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org, mchehab@kernel.org, hverkuil-cisco@xs4all.nl, sakari.ailus@linux.intel.com, andrey.konovalov@linaro.org, linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 4/9] media: qcom: camss: Fix VFE-17x vfe_disable_output() Message-ID: <20230828171541.GY14596@pendragon.ideasonboard.com> References: <20230822200626.1931129-1-bryan.odonoghue@linaro.org> <20230822200626.1931129-5-bryan.odonoghue@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230822200626.1931129-5-bryan.odonoghue@linaro.org> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi Bryan, Thank you for the patch. On Tue, Aug 22, 2023 at 09:06:21PM +0100, Bryan O'Donoghue wrote: > There are two problems with the current vfe_disable_output() routine. > > Firstly we rightly use a spinlock to protect output->gen2.active_num > everywhere except for in the IDLE timeout path of vfe_disable_output(). > Even if that is not racy "in practice" somehow it is by happenstance not > by design. > > Secondly we do not get consistent behaviour from this routine. On > sc8280xp 50% of the time I get "VFE idle timeout - resetting". In this > case the subsequent capture will succeed. The other 50% of the time, we > don't hit the idle timeout, never do the VFE reset and subsequent > captures stall indefinitely. > > Rewrite the vfe_disable_output() routine to > > - Quiesce write masters with vfe_wm_stop() > - Set active_num = 0 > > remembering to hold the spinlock when we do so followed by > > - Reset the VFE > > Testing on sc8280xp and sdm845 shows this to be a valid fix. > > Fixes: 7319cdf189bb ("media: camss: Add support for VFE hardware version Titan 170") > Cc: stable@vger.kernel.org > Signed-off-by: Bryan O'Donoghue I can't comment on the validity of the fix, but nothing shocks me in the patch, so I'm fine with it. > --- > .../media/platform/qcom/camss/camss-vfe-170.c | 19 +++---------------- > 1 file changed, 3 insertions(+), 16 deletions(-) > > diff --git a/drivers/media/platform/qcom/camss/camss-vfe-170.c b/drivers/media/platform/qcom/camss/camss-vfe-170.c > index 02494c89da91c..ae9137633c301 100644 > --- a/drivers/media/platform/qcom/camss/camss-vfe-170.c > +++ b/drivers/media/platform/qcom/camss/camss-vfe-170.c > @@ -500,28 +500,15 @@ static int vfe_disable_output(struct vfe_line *line) > struct vfe_output *output = &line->output; > unsigned long flags; > unsigned int i; > - bool done; > - int timeout = 0; > - > - do { > - spin_lock_irqsave(&vfe->output_lock, flags); > - done = !output->gen2.active_num; > - spin_unlock_irqrestore(&vfe->output_lock, flags); > - usleep_range(10000, 20000); Now that you don't sleep anymore, I think you can drop the inclusion of linux/delay.h. > - > - if (timeout++ == 100) { > - dev_err(vfe->camss->dev, "VFE idle timeout - resetting\n"); > - vfe_reset(vfe); > - output->gen2.active_num = 0; > - return 0; > - } > - } while (!done); > > spin_lock_irqsave(&vfe->output_lock, flags); > for (i = 0; i < output->wm_num; i++) > vfe_wm_stop(vfe, output->wm_idx[i]); > + output->gen2.active_num = 0; > spin_unlock_irqrestore(&vfe->output_lock, flags); > > + vfe_reset(vfe); > + > return 0; This function could become void, especially given that its only caller doesn't check the return value. > } > > -- > 2.41.0 > -- Regards, Laurent Pinchart