From: Lukas Wunner <lukas@wunner.de>
To: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Cc: bhelgaas@google.com, austin_bolen@dell.com,
alex_gagniuc@dellteam.com, keith.busch@intel.com,
Shyam_Iyer@Dell.com, okaya@kernel.org, linux-pci@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC v2 2/4] PCI: pciehp: Do not turn off slot if presence comes up after link
Date: Thu, 21 Feb 2019 08:36:34 +0100 [thread overview]
Message-ID: <20190221073634.snvazxlzgvjhilaz@wunner.de> (raw)
In-Reply-To: <20190220012031.10741-3-mr.nuke.me@gmail.com>
On Tue, Feb 19, 2019 at 07:20:28PM -0600, Alexandru Gagniuc wrote:
> @@ -213,6 +213,21 @@ void pciehp_handle_disable_request(struct controller *ctrl)
> ctrl->request_result = pciehp_disable_slot(ctrl, SAFE_REMOVAL);
> }
>
> +static bool is_delayed_presence_up_event(struct controller *ctrl, u32 events)
> +{
> + bool present, link_active;
> +
> + if (!ctrl->inband_presence_disabled)
> + return false;
> +
> + present = pciehp_card_present(ctrl);
> + link_active = pciehp_check_link_active(ctrl);
> +
> + if (!present || !link_active || events & PCI_EXP_SLTSTA_DLLSC)
> + return false;
> +
> + return true;
> +}
> void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
Newline please after the closing curly brace.
> @@ -220,13 +235,22 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
> /*
> * If the slot is on and presence or link has changed, turn it off.
> * Even if it's occupied again, we cannot assume the card is the same.
> + * When the card is swapped, we also expect a change in link state,
> + * without which, it's likely presence became high after link-active.
> */
Maybe it's just me but I find the code comment difficult to understand.
How about something along the lines of:
/*
* If the slot is on and presence or link has changed, turn it off.
* Even if it's occupied again, we cannot assume the card is the same.
+ *
+ * An exception is a delayed "Card present" after a "Link Up".
+ * This can happen on controllers with in-band presence disabled,
+ * PCIe r5.0 sec X.Y.Z.
*/
> mutex_lock(&ctrl->state_lock);
> + present = pciehp_card_present(ctrl);
> + link_active = pciehp_check_link_active(ctrl);
> switch (ctrl->state) {
These two assignments appear to be superfluous as you're also performing
them in pciehp_check_link_active().
Thanks,
Lukas
next prev parent reply other threads:[~2019-02-21 7:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 1:20 [PATCH RFC v2 0/4] PCI: pciehp: Do not turn off slot if presence comes up after link Alexandru Gagniuc
2019-02-20 1:20 ` [PATCH RFC v2 1/4] PCI: hotplug: Add support for disabling in-band presence Alexandru Gagniuc
2019-02-21 7:19 ` Lukas Wunner
2019-02-21 18:05 ` Alex_Gagniuc
2019-02-20 1:20 ` [PATCH RFC v2 2/4] PCI: pciehp: Do not turn off slot if presence comes up after link Alexandru Gagniuc
2019-02-21 7:36 ` Lukas Wunner [this message]
2019-02-22 19:56 ` Alex_Gagniuc
2019-02-23 6:49 ` Lukas Wunner
2019-02-24 22:27 ` Alex_Gagniuc
2019-02-20 1:20 ` [PATCH RFC v2 3/4] PCI: hotplug: Wait for PDS when in-band presence is disabled Alexandru Gagniuc
2019-02-20 1:20 ` [PATCH RFC v2 4/4] PCI: hotplug: Add quirk For Dell nvme pcie switches Alexandru Gagniuc
2019-02-21 7:56 ` Lukas Wunner
2019-02-21 18:35 ` Alex_Gagniuc
2019-02-22 1:20 ` Joe Perches
2019-02-22 2:04 ` Oliver
2019-02-22 19:19 ` Alex_Gagniuc
2019-02-21 15:38 ` [PATCH RFC v2 0/4] PCI: pciehp: Do not turn off slot if presence comes up after link Lukas Wunner
2019-02-21 18:17 ` Alex_Gagniuc
2019-04-19 0:01 ` Bjorn Helgaas
2019-04-19 15:22 ` [PATCH v3 " Alexandru Gagniuc
2019-04-19 15:22 ` [PATCH v3 1/4] PCI: hotplug: Add support for disabling in-band presence Alexandru Gagniuc
2019-04-19 15:22 ` [PATCH v3 2/4] PCI: pciehp: Do not turn off slot if presence comes up after link Alexandru Gagniuc
2019-04-19 15:22 ` [PATCH v3 3/4] PCI: hotplug: Wait for PDS when in-band presence is disabled Alexandru Gagniuc
2019-04-19 15:22 ` [PATCH v3 4/4] PCI: hotplug: Add quirk For Dell nvme pcie switches Alexandru Gagniuc
2019-04-19 21:00 ` Alan J. Wylie
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