From: "Krzysztof Wilczyński" <kw@linux.com>
To: Om Prakash Singh <omp@nvidia.com>
Cc: vidyas@nvidia.com, lorenzo.pieralisi@arm.com,
bhelgaas@google.com, thierry.reding@gmail.com,
jonathanh@nvidia.com, linux-tegra@vger.kernel.org,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
kthota@nvidia.com, mmaddireddy@nvidia.com
Subject: Re: [RESEND PATCH V1 3/5] PCI: tegra: Disable interrupts before entering L2
Date: Thu, 27 May 2021 14:13:10 +0200 [thread overview]
Message-ID: <20210527121310.GC213718@rocinante.localdomain> (raw)
In-Reply-To: <20210527115246.20509-4-omp@nvidia.com>
Hi Prakash,
> Tegra194 implements suspend_noirq() hook and during the system suspend, the link
> is taken to L2 state after PME_Turn_off handshake and if it doesn't go into L2,
> PERST# is asserted. It is observed that with some of the endpoints (Ex:- Marvell
> SATA controller), the link doesn't go into L2 state and asserting PERST# results
> in Surprise Link Down error and the corresponding AER interrupt is also raised.
> Since the system is in noirq phase, this interrupt is not served. Both PME and
> AER interrupts are served by the same wire interrupt in Tegra194, and since the
> PCIe sub-system enables wake capability for PME interrupt, having a pending AER
> interrupt is treated as PME wake interrupt by the system and prevents the system
> going into the suspend state. To address this issue, the interrupts are disabled
> before taking the link into L2 state as the interrupts are not expected anyway
> from the controller afterward.
This commit could use some formatting, perhaps splitting it into few
paragraphs and also I believe your line length could use some
adjustment. Having said that, I am not sure if the whole detailed
account of the problem is required to be included here in the commit
message.
> + /*
> + * PCIe controller exits from L2 only if reset is applied, so
> + * controller doesn't handle interrupts. But in cases where
> + * L2 entry fails, PERST# is asserted which can trigger surprise
> + * link down AER. However this function call happens in
> + * suspend_noirq(), so AER interrupt will not be processed.
> + * Disable all interrupts to avoid such a scenario.
> + */
[...]
This code comment added below makes for a better commit message that the
commit message above - clear, concise and straight to the point of why
this was added.
Krzysztof
next prev parent reply other threads:[~2021-05-27 12:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-27 11:52 [RESEND PATCH V1 0/5] Update pcie-tegra194 driver Om Prakash Singh
2021-05-27 11:52 ` [RESEND PATCH V1 1/5] PCI: tegra: Fix handling BME_CHGED event Om Prakash Singh
2021-05-27 16:06 ` Bjorn Helgaas
2021-05-27 11:52 ` [RESEND PATCH V1 2/5] PCI: tegra: Fix MSI-X programming Om Prakash Singh
2021-05-27 12:14 ` Krzysztof Wilczyński
2021-05-27 11:52 ` [RESEND PATCH V1 3/5] PCI: tegra: Disable interrupts before entering L2 Om Prakash Singh
2021-05-27 12:13 ` Krzysztof Wilczyński [this message]
2021-05-27 11:52 ` [RESEND PATCH V1 4/5] PCI: tegra: Don't allow suspend when Tegra PCIe is in EP mode Om Prakash Singh
2021-05-27 12:05 ` Krzysztof Wilczyński
2021-05-27 21:00 ` Krzysztof Wilczyński
2021-05-27 11:52 ` [RESEND PATCH V1 5/5] PCI: tegra: Cleanup unused code Om Prakash Singh
2021-05-27 12:00 ` [RESEND PATCH V1 0/5] Update pcie-tegra194 driver Krzysztof Wilczyński
2021-05-27 12:49 ` Jon Hunter
2021-05-27 12:52 ` Krzysztof Wilczyński
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