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Wed, 14 Aug 2024 06:54:15 +0000 (GMT) Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA01.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 47E6sE6Y000594 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 14 Aug 2024 06:54:14 GMT Received: from [10.239.132.245] (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; Tue, 13 Aug 2024 23:54:10 -0700 Message-ID: <4d89a048-eef0-4295-a4cc-500390f005d1@quicinc.com> Date: Wed, 14 Aug 2024 14:54:07 +0800 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] iommu/arm-smmu-qcom: remove runtime pm enabling for TBU driver To: Georgi Djakov , Pranjal Shrivastava CC: , , , , , , , , , Georgi Djakov References: <1722335443-30080-1-git-send-email-quic_zhenhuah@quicinc.com> <3cb1da06-88e3-4dd2-b56c-e0ab725ef6b2@quicinc.com> Content-Language: en-US From: Zhenhua Huang In-Reply-To: <3cb1da06-88e3-4dd2-b56c-e0ab725ef6b2@quicinc.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) 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-ORIG-GUID: pdVfXk8RUQ1JOGXNvkSnyCAy4DqL2LQ- X-Proofpoint-GUID: pdVfXk8RUQ1JOGXNvkSnyCAy4DqL2LQ- X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-08-14_04,2024-08-13_02,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 adultscore=0 phishscore=0 suspectscore=0 mlxscore=0 mlxlogscore=938 malwarescore=0 bulkscore=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2407110000 definitions=main-2408140046 Hi Georgi, On 2024/8/13 20:06, Georgi Djakov wrote: > Hi Zhenhua, > > On 8/13/2024 10:56 AM, Zhenhua Huang wrote: >> >> On 2024/8/13 15:20, Pranjal Shrivastava wrote: >>> On Tue, Aug 13, 2024 at 10:37:33AM +0800, Zhenhua Huang wrote: >>>> >>>> On 2024/8/12 21:25, Pranjal Shrivastava wrote: >>>>> On Tue, Jul 30, 2024 at 06:30:43PM +0800, Zhenhua Huang wrote: >>>>>> TBU driver has no runtime pm support now, adding pm_runtime_enable() >>>>>> seems to be useless. Remove it. >>>>>> >>>>>> Signed-off-by: Zhenhua Huang > [..] >>> I agree that there are no pm_runtime_suspend/resume calls within the TBU >>> driver. I'm just trying to understand why was pm_runtime enabled here >>> earlier (since it's not implemented) in order to ensure that removing it >>> doesn't cause further troubles? >> >> See above my assumption, need Georgi to comment but. > > Thank you for looking at the code! Your assumptions are mostly correct, > but if you try this patch on a real sdm845 device you will notice some > issues. So it's actually needed to re-configure the power-domains, three Thanks Georgi for your comments! Hmm... so you found some bugs on sdm845 ? sorry that I don't have sdm845 on hand... > of which (MMNOC GDSCs) are requiring this because of a HW bug. I should > have put a comment in the code to avoid confusion, but it took me some > time to confirm it. > > I have sent a patch to handle this more cleanly: > https://lore.kernel.org/lkml/20240813120015.3242787-1-quic_c_gdjako@quicinc.com > > So we should not remove the runtime pm calls until some version of the > above patch gets merged. In my sense, above patch should not result in turning off gdsc? It's just open the support for RPM.. I tried to do same change for arm-smmu driver, w/ test I see cx_gdsc which is the power-domain for gfx_smmu, is on: .. /sys/kernel/debug/pm_genpd/cx_gdsc # cat current_state on Are you worrying that not setting active will turn off related PD? or Could you please explain a bit more about how the change impacted power domain status? Thanks in advance :) > > Thanks, > Georgi > >>> I see Georgi added it as a part of >>> https://lore.kernel.org/all/20240704010759.507798-1-quic_c_gdjako@quicinc.com/ >>> >>> But I'm unsure why was it required to fix that bug? >> >> I'm just thinking it is dead code and want to see if my understanding is correct. > >