linux-kernel - Re: [PATCH v2 3/3] PCI: qcom: Add system PM support

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Message-ID: <20220518132757.GC4791@thinkpad>
Date:   Wed, 18 May 2022 18:57:57 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Christoph Hellwig <hch@....de>
Cc:     bhelgaas@...gle.com, lorenzo.pieralisi@....com, kbusch@...nel.org,
        linux-nvme@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        svarbanov@...sol.com, bjorn.andersson@...aro.org, axboe@...com,
        quic_vbadigan@...cinc.com, quic_krichai@...cinc.com,
        quic_nitirawa@...cinc.com, vidyas@...dia.com, sagi@...mberg.me,
        linux-pm@...r.kernel.org, rafael@...nel.org,
        Prasad Malisetty <quic_pmaliset@...cinc.com>
Subject: Re: [PATCH v2 3/3] PCI: qcom: Add system PM support

On Wed, May 18, 2022 at 03:23:58PM +0200, Christoph Hellwig wrote:
> On Wed, May 18, 2022 at 06:49:13PM +0530, Manivannan Sadhasivam wrote:
> > From: Prasad Malisetty <quic_pmaliset@...cinc.com>
> > 
> > Add suspend and resume callbacks to handle system suspend and resume in
> > the Qcom PCIe controller driver. When the system suspends, PME turnoff
> > message will be sent to the device and the RC driver will wait for the
> > device to enter L23 Ready state. After that, the PHY will be powered down
> > and clocks/regulators will be disabled.
> 
> So what about just not doing this stupid power disabling to start
> with?  Unlike x86 where we do not have choice due to the BIOS, we
> apparently do here.  And disabling power is the wrong thing to do at
> least for SSDs as it massively increases the wear on the NAND.

That's the requirement the Chromebook based on SC7280 has. I will check
internally and get back.

Thanks,
Mani

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