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Mon, 22 Apr 2024 17:23:20 +0000 (GMT) Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA05.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 43MHNJWe005527 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 22 Apr 2024 17:23:19 GMT Received: from [10.71.109.81] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 22 Apr 2024 10:23:19 -0700 Message-ID: <7daeeaba-a33d-bf05-1371-d9b5fa0bf0a5@quicinc.com> Date: Mon, 22 Apr 2024 10:23:18 -0700 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH 1/3] drm/msm: don't clean up priv->kms prematurely Content-Language: en-US To: Dmitry Baryshkov CC: Rob Clark , Sean Paul , Marijn Suijten , David Airlie , Daniel Vetter , , , , References: <20240420-mdp4-fixes-v1-0-96a70f64fa85@linaro.org> <20240420-mdp4-fixes-v1-1-96a70f64fa85@linaro.org> <67fbd629-3e80-b706-83a3-7baff3efd6c1@quicinc.com> From: Abhinav Kumar In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: Gik2XTWn6sjBZbjbXowMENMblUen81bD X-Proofpoint-ORIG-GUID: Gik2XTWn6sjBZbjbXowMENMblUen81bD X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-22_09,2024-04-22_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 mlxlogscore=740 mlxscore=0 malwarescore=0 clxscore=1015 adultscore=0 bulkscore=0 spamscore=0 phishscore=0 lowpriorityscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2404010003 definitions=main-2404220072 On 4/21/2024 3:35 PM, Dmitry Baryshkov wrote: > On Sat, Apr 20, 2024 at 04:02:00PM -0700, Abhinav Kumar wrote: >> >> >> On 4/19/2024 7:33 PM, Dmitry Baryshkov wrote: >>> MSM display drivers provide kms structure allocated during probe(). >>> Don't clean up priv->kms field in case of an error. Otherwise probe >>> functions might fail after KMS probe deferral. >>> >> >> So just to understand this more, this will happen when master component >> probe (dpu) succeeded but other sub-component probe (dsi) deferred? >> >> Because if master component probe itself deferred it will allocate priv->kms >> again isnt it and we will not even hit here. > > Master probing succeeds (so priv->kms is set), then kms_init fails at > runtime, during binding of the master device. This results in probe > deferral from the last component's component_add() function and reprobe > attempt when possible (once the next device is added or probed). However > as priv->kms is NULL, probe crashes. > >> >>> Fixes: a2ab5d5bb6b1 ("drm/msm: allow passing struct msm_kms to msm_drv_probe()") Actually, Is this Fixes tag correct? OR is this one better Fixes: 506efcba3129 ("drm/msm: carve out KMS code from msm_drv.c") >>> Signed-off-by: Dmitry Baryshkov >>> --- >>> drivers/gpu/drm/msm/msm_kms.c | 1 - >>> 1 file changed, 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c >>> index af6a6fcb1173..6749f0fbca96 100644 >>> --- a/drivers/gpu/drm/msm/msm_kms.c >>> +++ b/drivers/gpu/drm/msm/msm_kms.c >>> @@ -244,7 +244,6 @@ int msm_drm_kms_init(struct device *dev, const struct drm_driver *drv) >>> ret = priv->kms_init(ddev); >>> if (ret) { >>> DRM_DEV_ERROR(dev, "failed to load kms\n"); >>> - priv->kms = NULL; >>> return ret; >>> } >>> >