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Wed, 24 Jul 2024 16:51:21 +0000 (GMT) Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA04.qualcomm.com (8.17.1.19/8.17.1.19) with ESMTPS id 46OGpKHm004312 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Jul 2024 16:51:20 GMT Received: from [10.110.5.87] (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; Wed, 24 Jul 2024 09:51:19 -0700 Message-ID: <5c4a230e-ed7b-44d4-a2a3-0ecb9e784dd0@quicinc.com> Date: Wed, 24 Jul 2024 09:51:19 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2 0/7] Add power domain and MSI functionality with PCIe host generic ECAM driver To: Dmitry Baryshkov , Manivannan Sadhasivam CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <1721067215-5832-1-git-send-email-quic_mrana@quicinc.com> <20240724133139.GB3349@thinkpad> Content-Language: en-US From: Mayank Rana In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] 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: 8D5wnAS4-Q6Bf-cJ3f4W_J0JI9vlffhP X-Proofpoint-GUID: 8D5wnAS4-Q6Bf-cJ3f4W_J0JI9vlffhP 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=2024-07-24_17,2024-07-24_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 bulkscore=0 malwarescore=0 suspectscore=0 mlxscore=0 clxscore=1015 phishscore=0 spamscore=0 adultscore=0 mlxlogscore=850 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2407110000 definitions=main-2407240121 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240724_095134_182160_9DF2EB8F X-CRM114-Status: GOOD ( 16.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/24/2024 6:34 AM, Dmitry Baryshkov wrote: > On Wed, 24 Jul 2024 at 16:31, Manivannan Sadhasivam > wrote: >> >> On Wed, Jul 24, 2024 at 10:12:17AM +0300, Dmitry Baryshkov wrote: >>> On Wed, 24 Jul 2024 at 06:58, Mayank Rana wrote: >>>> >>>> >>>> >>>> On 7/23/2024 7:13 PM, Dmitry Baryshkov wrote: >>>>> On Mon, Jul 15, 2024 at 11:13:28AM GMT, Mayank Rana wrote: >>>>>> Based on previously received feedback, this patch series adds functionalities >>>>>> with existing PCIe host generic ECAM driver (pci-host-generic.c) to get PCIe >>>>>> host root complex functionality on Qualcomm SA8775P auto platform. >>>>>> >>>>>> Previously sent RFC patchset to have separate Qualcomm PCIe ECAM platform driver: >>>>>> https://lore.kernel.org/all/d10199df-5fb3-407b-b404-a0a4d067341f@quicinc.com/T/ >>>>>> >>>>>> 1. Interface to allow requesting firmware to manage system resources and performing >>>>>> PCIe Link up (devicetree binding in terms of power domain and runtime PM APIs is used in driver) >>>>>> 2. Performing D3 cold with system suspend and D0 with system resume (usage of GenPD >>>>>> framework based power domain controls these operations) >>>>>> 3. SA8775P is using Synopsys Designware PCIe controller which supports MSI controller. >>>>>> This MSI functionality is used with PCIe host generic driver after splitting existing MSI >>>>>> functionality from pcie-designware-host.c file into pcie-designware-msi.c file. >>>>> >>>>> Please excuse me my ignorance if this is described somewhere. Why are >>>>> you using DWC-specific MSI handling instead of using GIC ITS? >>>> Due to usage of GIC v3 on SA8775p with Gunyah hypervisor, we have >>>> limitation of not supporting GIC ITS >>>> functionality. We considered other approach as usage of free SPIs (not >>>> available, limitation in terms of mismatch between number of SPIs >>>> available with physical GIC vs hypervisor) and extended SPIs (not >>>> supported with GIC hardware). Hence we just left with DWC-specific MSI >>>> controller here for MSI functionality. >>> >>> ... or extend Gunyah to support GIC ITS. I'd say it is a significant >>> deficiency if one can not use GIC ITS on Gunyah platforms. >>> >> >> It if were possible, Qcom would've went with that. Unfortunately, it is not. > > Ack. > Mayank, if the patch gets resent for any reason, please add this to > the commit message. ACK. Regards, Mayank >> >> - Mani >> >> -- >> மணிவண்ணன் சதாசிவம் > > >