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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AEF97C433F5 for ; Wed, 5 Jan 2022 21:34:51 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A1DFE10E1FE; Wed, 5 Jan 2022 21:34:50 +0000 (UTC) Received: from mail-oi1-x235.google.com (mail-oi1-x235.google.com [IPv6:2607:f8b0:4864:20::235]) by gabe.freedesktop.org (Postfix) with ESMTPS id E72A710E1FE for ; Wed, 5 Jan 2022 21:34:48 +0000 (UTC) Received: by mail-oi1-x235.google.com with SMTP id w7so999677oiw.0 for ; Wed, 05 Jan 2022 13:34:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:in-reply-to:references:from:user-agent:date:message-id :subject:to:cc; bh=aikMCKgudfdNFplAVHd5dZZXnejy0/EJjuSG/0Dh+Qk=; b=nojXfc3QeDa4iaP71sncYrCB3wu7bLLyOe3E6RLAx+SoyIv3/xzrXSplCVbTaqycvs jNlEcorkEg3VtM6xmPuL5OnmRIjchtMFOWw/kWuJQ3rJQGIkvo/eqxUo5B7jMsgSX/mw xLLXbTEalgpY7wNm4bRtUSyYCxO6JUWHZyDZE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:in-reply-to:references:from :user-agent:date:message-id:subject:to:cc; bh=aikMCKgudfdNFplAVHd5dZZXnejy0/EJjuSG/0Dh+Qk=; b=1OotrAsNFiP+gAktAKG0UCwqDHRGs7M8p9QfaYQkppQbbQseQ9ks2GDTBMGZDW+UK8 0jcUMO1H5U5W1evKteIkdzhMl40FQN+RLKXk5KMWdXV9WHYGoYoxAAKc7sy7VP8pm8mt FoPTanefgI2k5ZbPx2gpLZTMiM7eFtw14yTvLhXGefrPZnQxKJ7SOtuRaRKPwIU3Cnjo Ihb9KXlpD8MizdsZyoqAVRlEG4angp5U9fh1384r2CfIN90OBpSnsnJtaeIFEMlfHIzX CFI7nesMYsgvYRioW/9+yGuTaJ7+y8WbWVnxwC7KruAxqB3Uj3Cl4gy9MooB78hfxWRB p+4w== X-Gm-Message-State: AOAM531TF4BXkmrD0JMT8DA7Nn2ZBxZrdTkIFHKcIHZvNwHk/Xhu4Mv9 DZucsIsEJS/7KRmsZgKvb7JNeYC1tmSmzp6qHWgK3w== X-Google-Smtp-Source: ABdhPJz8SSN2Fj+FwJmMI6TRwdHCqoAnptzNFxaptsVJlo0Hr4xuSL1iBnb3nFWwft46rigEC0UuSxDvQnlNciU7W5Q= X-Received: by 2002:a54:4710:: with SMTP id k16mr4028697oik.32.1641418488161; Wed, 05 Jan 2022 13:34:48 -0800 (PST) Received: from 753933720722 named unknown by gmailapi.google.com with HTTPREST; Wed, 5 Jan 2022 13:34:47 -0800 MIME-Version: 1.0 In-Reply-To: <1640805422-21904-1-git-send-email-quic_khsieh@quicinc.com> References: <1640805422-21904-1-git-send-email-quic_khsieh@quicinc.com> From: Stephen Boyd User-Agent: alot/0.9.1 Date: Wed, 5 Jan 2022 13:34:47 -0800 Message-ID: Subject: Re: [PATCH v2] drm/msm/dp: populate connector of struct dp_panel To: Kuogee Hsieh , agross@kernel.org, airlied@linux.ie, bjorn.andersson@linaro.org, daniel@ffwll.ch, dmitry.baryshkov@linaro.org, robdclark@gmail.com, sean@poorly.run, vkoul@kernel.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: quic_sbillaka@quicinc.com, linux-arm-msm@vger.kernel.org, quic_abhinavk@quicinc.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, aravindh@codeaurora.org, freedreno@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Quoting Kuogee Hsieh (2021-12-29 11:17:02) > There is kernel crashed due to unable to handle kernel NULL > pointer dereference of dp_panel->connector while running DP link > layer compliance test case 4.2.2.6 (EDID Corruption Detection). Can you explain how we get into that situation? Like "We never assign struct dp_panel::connector, instead the connector is stored in struct msm_dp::connector. When we run compliance testing test case 4.2.2.6 dp_panel_handle_sink_request() won't have a valid edid set in struct dp_panel::edid so we'll try to use the connectors real_edid_checksum and hit a NULL pointer deref error because the connector pointer is never assigned." > This patch fixes this problem by populating connector of dp_panel. > > [drm:dp_panel_read_sink_caps] *ERROR* panel edid read failed > Unable to handle kernel NULL pointer dereference at virtual address 00000000000006e1 > Mem abort info: > ESR = 0x96000006 > EC = 0x25: DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > Data abort info: > ISV = 0, ISS = 0x00000006 > CM = 0, WnR = 0 > user pgtable: 4k pages, 39-bit VAs, pgdp=0000000115f25000 > [00000000000006e1] pgd=00000001174fe003, p4d=00000001174fe003, pud=00000001174fe003, pmd=0000000000000000 > Internal error: Oops: 96000006 [#1] PREEMPT SMP This sort of stuff isn't really useful because it takes quite a few lines to say "We hit a NULL pointer deref" which was already stated. I'd rather have a clear description of what goes wrong and how setting the pointer in msm_dp_modeset_init() fixes it. > {...] > > Changes in V2: > -- populate panel connector at msm_dp_modeset_init() instead of at dp_panel_read_sink_caps() > > Fixes: 7948fe12d47 ("drm/msm/dp: return correct edid checksum after corrupted edid checksum read") > Signee-off-by: Kuogee Hsieh > --- > drivers/gpu/drm/msm/dp/dp_display.c | 25 +++++++++++++++---------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c > index 3449d3f..c282bbf 100644 > --- a/drivers/gpu/drm/msm/dp/dp_display.c > +++ b/drivers/gpu/drm/msm/dp/dp_display.c > @@ -1495,36 +1495,41 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor) > } > } > > -int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev, > +int msm_dp_modeset_init(struct msm_dp *dp, struct drm_device *dev, > struct drm_encoder *encoder) > { > struct msm_drm_private *priv; > + struct dp_display_private *dp_display; > int ret; > > - if (WARN_ON(!encoder) || WARN_ON(!dp_display) || WARN_ON(!dev)) > + if (WARN_ON(!encoder) || WARN_ON(!dp) || WARN_ON(!dev)) > return -EINVAL; > > priv = dev->dev_private; > - dp_display->drm_dev = dev; > + dp->drm_dev = dev; > + > + dp_display = container_of(dp, struct dp_display_private, dp_display); > > - ret = dp_display_request_irq(dp_display); > + ret = dp_display_request_irq(dp); > if (ret) { > DRM_ERROR("request_irq failed, ret=%d\n", ret); > return ret; > } > > - dp_display->encoder = encoder; > + dp->encoder = encoder; > > - dp_display->connector = dp_drm_connector_init(dp_display); > - if (IS_ERR(dp_display->connector)) { > - ret = PTR_ERR(dp_display->connector); > + dp->connector = dp_drm_connector_init(dp); > + if (IS_ERR(dp->connector)) { > + ret = PTR_ERR(dp->connector); > DRM_DEV_ERROR(dev->dev, > "failed to create dp connector: %d\n", ret); > - dp_display->connector = NULL; > + dp->connector = NULL; > return ret; > } > > - priv->connectors[priv->num_connectors++] = dp_display->connector; > + dp_display->panel->connector = dp->connector; This is the one line that matters I think? Can we reach the connector for the dp device without going through the panel in dp_panel_handle_sink_request()? That would reduce the number of struct elements if possible. > + > + priv->connectors[priv->num_connectors++] = dp->connector; Can we not rename all the local variables in this patch and do it later or never? Reading this patch takes a long time because we have to make sure nothing has actually changed with the rename of 'dp_display' to 'dp'. > return 0; > } > > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project >