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Wysocki" Cc: Christoph Hellwig , Ulf Hansson , "Rafael J. Wysocki" , Bjorn Helgaas , kbusch@kernel.org, axboe@kernel.dk, sagi@grimberg.me, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, andersson@kernel.org, konradybcio@kernel.org, Len Brown , linux-pm@vger.kernel.org Subject: Re: [PATCH] nvme-pci: Shutdown the device if D3Cold is allowed by the user Message-ID: <20241216164830.36lpu6gfnapsdar4@thinkpad> References: <20241205232900.GA3072557@bhelgaas> <20241209143821.m4dahsaqeydluyf3@thinkpad> <20241212055920.GB4825@lst.de> <13662231.uLZWGnKmhe@rjwysocki.net> <20241212151354.GA7708@lst.de> <20241214063023.4tdvjbqd2lrylb7o@thinkpad> <20241216162303.GA26434@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241216_084838_116750_AE4C5733 X-CRM114-Status: GOOD ( 19.89 ) X-BeenThere: linux-nvme@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-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Dec 16, 2024 at 05:42:30PM +0100, Rafael J. Wysocki wrote: > On Mon, Dec 16, 2024 at 5:23 PM Christoph Hellwig wrote: > > > > On Sat, Dec 14, 2024 at 12:00:23PM +0530, Manivannan Sadhasivam wrote: > > > We need a PM core API that tells the device drivers when it is safe to powerdown > > > the devices. The usecase here is with PCIe based NVMe devices but the problem is > > > applicable to other devices as well. > > > > Maybe I'm misunderstanding things, but I think the important part is > > to indicate when a suspend actually MUST put the device into D3. Because > > doing that should always be safe, but not always optimal. > > I'm not aware of any cases when a device must be put into D3cold > (which I think is what you mean) during system-wide suspend. > > Suspend-to-idle on x86 doesn't require this, at least not for > correctness. I don't think any platforms using DT require it either. > On suspend-to-idle, yes D3Cold doesn't make sense, but on suspend-to-ram it is pretty much required. That applies to DT as well. - Mani -- மணிவண்ணன் சதாசிவம்