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From: Bjorn Helgaas <helgaas@kernel.org>
To: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Cc: linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, mka@chromium.org,
	quic_vbadigan@quicinc.com, quic_hemantk@quicinc.com,
	quic_nitegupt@quicinc.com, quic_skananth@quicinc.com,
	quic_ramkri@quicinc.com, manivannan.sadhasivam@linaro.org,
	swboyd@chromium.org, dmitry.baryshkov@linaro.org,
	svarbanov@mm-sol.com, agross@kernel.org, andersson@kernel.org,
	konrad.dybcio@somainline.org, lpieralisi@kernel.org,
	robh@kernel.org, kw@linux.com, bhelgaas@google.com,
	linux-phy@lists.infradead.org, vkoul@kernel.org, kishon@ti.com,
	mturquette@baylibre.com, linux-clk@vger.kernel.org,
	Bjorn Andersson <bjorn.andersson@linaro.org>
Subject: Re: [PATCH v7 1/5] PCI: qcom: Add system suspend and resume support
Date: Tue, 20 Sep 2022 13:16:37 -0500	[thread overview]
Message-ID: <20220920181637.GA1121154@bhelgaas> (raw)
In-Reply-To: <1663669347-29308-2-git-send-email-quic_krichai@quicinc.com>

On Tue, Sep 20, 2022 at 03:52:23PM +0530, Krishna chaitanya chundru wrote:
> Add suspend and resume syscore ops.
> 
> Few PCIe endpoints like NVMe and WLANs are always expecting the device
> to be in D0 state and the link to be active (or in l1ss) all the time
> (including in S3 state).

What does this have to do with the patch?  I don't see any NVMe or
WLAN patches here.

> In qcom platform PCIe resources( clocks, phy etc..) can released
> when the link is in L1ss to reduce the power consumption. So if the link
> is in L1ss, release the PCIe resources. And when the system resumes,
> enable the PCIe resources if they released in the suspend path.

What's the connection with L1.x?  Links enter L1.x based on activity
and timing.  That doesn't seem like a reliable indicator to turn PHYs
off and disable clocks.

> is_suspended flag indicates if the PCIe resources are released or not
> in the suspend path.

Why is "is_suspended" important for the commit log?  It looks like
just a standard implementation detail.

> Its observed that access to Ep PCIe space to mask MSI/MSIX is happening
> at the very late stage of suspend path (access by affinity changes while
> making CPUs offline during suspend, this will happen after devices are
> suspended (after all phases of suspend ops)). If we turn off clocks in
> any PM callback, afterwards running into crashes due to un-clocked access
> due to above mentioned MSI/MSIx access.
> So, we are making use of syscore framework to turn off the PCIe clocks
> which will be called after making CPUs offline.

Add blank lines between paragraphs.  Or rewrap into a single paragraph.

s/Its observed/It's observed/
s/MSIX/MSI-X/ throughout
s/MSIx/MSI-X/ throughout

Bjorn

WARNING: multiple messages have this Message-ID (diff)
From: Bjorn Helgaas <helgaas@kernel.org>
To: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Cc: linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, mka@chromium.org,
	quic_vbadigan@quicinc.com, quic_hemantk@quicinc.com,
	quic_nitegupt@quicinc.com, quic_skananth@quicinc.com,
	quic_ramkri@quicinc.com, manivannan.sadhasivam@linaro.org,
	swboyd@chromium.org, dmitry.baryshkov@linaro.org,
	svarbanov@mm-sol.com, agross@kernel.org, andersson@kernel.org,
	konrad.dybcio@somainline.org, lpieralisi@kernel.org,
	robh@kernel.org, kw@linux.com, bhelgaas@google.com,
	linux-phy@lists.infradead.org, vkoul@kernel.org, kishon@ti.com,
	mturquette@baylibre.com, linux-clk@vger.kernel.org,
	Bjorn Andersson <bjorn.andersson@linaro.org>
Subject: Re: [PATCH v7 1/5] PCI: qcom: Add system suspend and resume support
Date: Tue, 20 Sep 2022 13:16:37 -0500	[thread overview]
Message-ID: <20220920181637.GA1121154@bhelgaas> (raw)
In-Reply-To: <1663669347-29308-2-git-send-email-quic_krichai@quicinc.com>

On Tue, Sep 20, 2022 at 03:52:23PM +0530, Krishna chaitanya chundru wrote:
> Add suspend and resume syscore ops.
> 
> Few PCIe endpoints like NVMe and WLANs are always expecting the device
> to be in D0 state and the link to be active (or in l1ss) all the time
> (including in S3 state).

What does this have to do with the patch?  I don't see any NVMe or
WLAN patches here.

> In qcom platform PCIe resources( clocks, phy etc..) can released
> when the link is in L1ss to reduce the power consumption. So if the link
> is in L1ss, release the PCIe resources. And when the system resumes,
> enable the PCIe resources if they released in the suspend path.

What's the connection with L1.x?  Links enter L1.x based on activity
and timing.  That doesn't seem like a reliable indicator to turn PHYs
off and disable clocks.

> is_suspended flag indicates if the PCIe resources are released or not
> in the suspend path.

Why is "is_suspended" important for the commit log?  It looks like
just a standard implementation detail.

> Its observed that access to Ep PCIe space to mask MSI/MSIX is happening
> at the very late stage of suspend path (access by affinity changes while
> making CPUs offline during suspend, this will happen after devices are
> suspended (after all phases of suspend ops)). If we turn off clocks in
> any PM callback, afterwards running into crashes due to un-clocked access
> due to above mentioned MSI/MSIx access.
> So, we are making use of syscore framework to turn off the PCIe clocks
> which will be called after making CPUs offline.

Add blank lines between paragraphs.  Or rewrap into a single paragraph.

s/Its observed/It's observed/
s/MSIX/MSI-X/ throughout
s/MSIx/MSI-X/ throughout

Bjorn

-- 
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy

  reply	other threads:[~2022-09-20 18:16 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20 10:22 [PATCH v7 0/5] PCI: qcom: Add system suspend & resume support Krishna chaitanya chundru
2022-09-20 10:22 ` Krishna chaitanya chundru
2022-09-20 10:22 ` [PATCH v7 1/5] PCI: qcom: Add system suspend and " Krishna chaitanya chundru
2022-09-20 10:22   ` Krishna chaitanya chundru
2022-09-20 18:16   ` Bjorn Helgaas [this message]
2022-09-20 18:16     ` Bjorn Helgaas
2022-09-21  9:53     ` Krishna Chaitanya Chundru
2022-09-21  9:53       ` Krishna Chaitanya Chundru
2022-09-21 16:56       ` Bjorn Helgaas
2022-09-21 16:56         ` Bjorn Helgaas
2022-09-22 15:39         ` Krishna Chaitanya Chundru
2022-09-22 15:39           ` Krishna Chaitanya Chundru
2022-09-22 18:42           ` Bjorn Helgaas
2022-09-22 18:42             ` Bjorn Helgaas
2022-09-23  1:59             ` Krishna Chaitanya Chundru
2022-09-23  1:59               ` Krishna Chaitanya Chundru
2022-09-23 14:26               ` Bjorn Helgaas
2022-09-23 14:26                 ` Bjorn Helgaas
2022-09-25  1:53                 ` Krishna Chaitanya Chundru
2022-09-25  1:53                   ` Krishna Chaitanya Chundru
2022-09-28 14:32                   ` Krishna Chaitanya Chundru
2022-09-28 14:32                     ` Krishna Chaitanya Chundru
2022-09-26 15:30                 ` Krishna Chaitanya Chundru
2022-09-26 15:30                   ` Krishna Chaitanya Chundru
2022-09-29 18:53                   ` Bjorn Helgaas
2022-09-29 18:53                     ` Bjorn Helgaas
2022-10-03 12:10                     ` Krishna Chaitanya Chundru
2022-10-03 12:10                       ` Krishna Chaitanya Chundru
2022-10-05 21:13                       ` Bjorn Helgaas
2022-10-05 21:13                         ` Bjorn Helgaas
2022-10-12 14:06                         ` Krishna Chaitanya Chundru
2022-10-12 14:06                           ` Krishna Chaitanya Chundru
2022-10-13  0:44                           ` Bjorn Helgaas
2022-10-13  0:44                             ` Bjorn Helgaas
2022-09-20 21:58   ` Jeff Johnson
2022-09-20 21:58     ` Jeff Johnson
2022-09-20 10:22 ` [PATCH v7 2/5] PCI: qcom: Add retry logic for link to be stable in either L1.1 or L1.2 Krishna chaitanya chundru
2022-09-20 10:22   ` Krishna chaitanya chundru
2022-09-20 22:00   ` Jeff Johnson
2022-09-20 22:00     ` Jeff Johnson
2022-09-24  6:05   ` Vinod Koul
2022-09-24  6:05     ` Vinod Koul
2022-09-25  1:51     ` Krishna Chaitanya Chundru
2022-09-25  1:51       ` Krishna Chaitanya Chundru
2022-09-20 10:22 ` [PATCH v7 3/5] phy: core: Add support for phy suspend & resume Krishna chaitanya chundru
2022-09-20 10:22   ` Krishna chaitanya chundru
2022-09-20 10:22 ` [PATCH v7 4/5] phy: qcom: Add power suspend & resume callbacks to PCIe phy Krishna chaitanya chundru
2022-09-20 10:22   ` Krishna chaitanya chundru
2022-09-20 10:22 ` [PATCH v7 5/5] clk: qcom: gcc-sc7280: Update the .pwrsts for PCIe GDSC Krishna chaitanya chundru
2022-09-20 10:22   ` Krishna chaitanya chundru
2022-09-27  3:23 ` (subset) [PATCH v7 0/5] PCI: qcom: Add system suspend & resume support Bjorn Andersson
2022-09-27  3:23   ` Bjorn Andersson

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