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 4B427C433F5 for ; Sat, 5 Feb 2022 11:53:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376676AbiBELxa (ORCPT ); Sat, 5 Feb 2022 06:53:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358916AbiBELx3 (ORCPT ); Sat, 5 Feb 2022 06:53:29 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DCEDBC061347; Sat, 5 Feb 2022 03:53:28 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7CFF460C8E; Sat, 5 Feb 2022 11:53:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FDF1C340E8; Sat, 5 Feb 2022 11:53:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644062007; bh=lUBbvL5wH7PnC+Gd4WGcambxq9nvtgxEqvEU6mzfiRo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bhK7ZDiqSab8DUUIr/SuKZlRlf3Apz37KIjRYW5ESXygnA1T0E43ssRgZ5oS8jDVy fHty8+NsYap5H0Zd3LnvjrPWKJ3lzbeZGnt6gYrVB3f+QTmCnfocYQvJf6oJNCE7nB gHo2Js3WCg6ZXbimc4OenCAYUOfWqV9zA4w2F/7U= Date: Sat, 5 Feb 2022 12:53:24 +0100 From: Greg Kroah-Hartman To: Alexey Khoroshilov Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Michael Stapelberg , Maxime Ripard Subject: Re: [PATCH 5.10 12/25] drm/vc4: hdmi: Make sure the device is powered with CEC Message-ID: References: <20220204091914.280602669@linuxfoundation.org> <20220204091914.688259001@linuxfoundation.org> <91a59ee1-cca4-8d0c-4f86-388434eb5a39@ispras.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <91a59ee1-cca4-8d0c-4f86-388434eb5a39@ispras.ru> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sat, Feb 05, 2022 at 02:40:37PM +0300, Alexey Khoroshilov wrote: > On 04.02.2022 12:20, Greg Kroah-Hartman wrote: > > From: Maxime Ripard > > > > Commit 20b0dfa86bef0e80b41b0e5ac38b92f23b6f27f9 upstream. > > > > The original commit depended on a rework commit (724fc856c09e ("drm/vc4: > > hdmi: Split the CEC disable / enable functions in two")) that > > (rightfully) didn't reach stable. > > > > However, probably because the context changed, when the patch was > > applied to stable the pm_runtime_put called got moved to the end of the > > vc4_hdmi_cec_adap_enable function (that would have become > > vc4_hdmi_cec_disable with the rework) to vc4_hdmi_cec_init. > > > > This means that at probe time, we now drop our reference to the clocks > > and power domains and thus end up with a CPU hang when the CPU tries to > > access registers. > > > > The call to pm_runtime_resume_and_get() is also problematic since the > > .adap_enable CEC hook is called both to enable and to disable the > > controller. That means that we'll now call pm_runtime_resume_and_get() > > at disable time as well, messing with the reference counting. > > > > The behaviour we should have though would be to have > > pm_runtime_resume_and_get() called when the CEC controller is enabled, > > and pm_runtime_put when it's disabled. > > > > We need to move things around a bit to behave that way, but it aligns > > stable with upstream. > > > > Cc: # 5.10.x > > Cc: # 5.15.x > > Cc: # 5.16.x > > Reported-by: Michael Stapelberg > > Signed-off-by: Maxime Ripard > > Signed-off-by: Greg Kroah-Hartman > > --- > > drivers/gpu/drm/vc4/vc4_hdmi.c | 27 ++++++++++++++------------- > > 1 file changed, 14 insertions(+), 13 deletions(-) > > > > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c > > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c > > @@ -1402,18 +1402,18 @@ static int vc4_hdmi_cec_adap_enable(stru > > u32 val; > > int ret; > > > > - ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev); > > - if (ret) > > - return ret; > > - > > - val = HDMI_READ(HDMI_CEC_CNTRL_5); > > - val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET | > > - VC4_HDMI_CEC_CNT_TO_4700_US_MASK | > > - VC4_HDMI_CEC_CNT_TO_4500_US_MASK); > > - val |= ((4700 / usecs) << VC4_HDMI_CEC_CNT_TO_4700_US_SHIFT) | > > - ((4500 / usecs) << VC4_HDMI_CEC_CNT_TO_4500_US_SHIFT); > > - > > if (enable) { > > + ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev); > > + if (ret) > > + return ret; > > + > > + val = HDMI_READ(HDMI_CEC_CNTRL_5); > > + val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET | > > + VC4_HDMI_CEC_CNT_TO_4700_US_MASK | > > + VC4_HDMI_CEC_CNT_TO_4500_US_MASK); > > + val |= ((4700 / usecs) << VC4_HDMI_CEC_CNT_TO_4700_US_SHIFT) | > > + ((4500 / usecs) << VC4_HDMI_CEC_CNT_TO_4500_US_SHIFT); > > + > > HDMI_WRITE(HDMI_CEC_CNTRL_5, val | > > VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET); > > HDMI_WRITE(HDMI_CEC_CNTRL_5, val); > > @@ -1439,7 +1439,10 @@ static int vc4_hdmi_cec_adap_enable(stru > > HDMI_WRITE(HDMI_CEC_CPU_MASK_SET, VC4_HDMI_CPU_CEC); > > HDMI_WRITE(HDMI_CEC_CNTRL_5, val | > > VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET); > > + > > + pm_runtime_put(&vc4_hdmi->pdev->dev); > > } > > + > > return 0; > > } > > > > @@ -1531,8 +1534,6 @@ static int vc4_hdmi_cec_init(struct vc4_ > > if (ret < 0) > > goto err_delete_cec_adap; > > > > - pm_runtime_put(&vc4_hdmi->pdev->dev); > > - > > return 0; > > > > err_delete_cec_adap: > > > > > > The patch has moved initialization of val local variable into if > (enable) branch. But the variable is used in in the else branch as well. > As a result we write of its initialized value here: > > HDMI_WRITE(HDMI_CEC_CNTRL_5, val | > VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET); > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > static > int vc4_hdmi_cec_adap_enable(struct cec_adapter *adap, bool enable) > { > struct vc4_hdmi *vc4_hdmi = cec_get_drvdata(adap); > /* clock period in microseconds */ > const u32 usecs = 1000000 / CEC_CLOCK_FREQ; > u32 val; > int ret; > > if (enable) { > ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev); > if (ret) > return ret; > > val = HDMI_READ(HDMI_CEC_CNTRL_5); > ..... > > } else { > HDMI_WRITE(HDMI_CEC_CPU_MASK_SET, VC4_HDMI_CPU_CEC); > HDMI_WRITE(HDMI_CEC_CNTRL_5, val | <------------------ UNINIT VALUE > VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET); > > pm_runtime_put(&vc4_hdmi->pdev->dev); > } > > return 0; > } So what does this mean? That this backport is incorrect and should be dropped? Or that the original commit was wrong? Or something else? confused, greg k-h