linux-kernel - Re: [PATCH v4 0/3] PCI: pciehp: Do not turn off slot if presence comes up after link

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Date:   Tue, 11 Feb 2020 05:49:40 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Stuart Hayes <stuart.w.hayes@...il.com>,
        Austin Bolen <austin_bolen@...l.com>, keith.busch@...el.com,
        Alexandru Gagniuc <mr.nuke.me@...il.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        "Gustavo A . R . Silva" <gustavo@...eddedor.com>,
        Sinan Kaya <okaya@...nel.org>,
        Oza Pawandeep <poza@...eaurora.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, Libor Pechacek <lpechacek@...e.cz>
Subject: Re: [PATCH v4 0/3] PCI: pciehp: Do not turn off slot if presence
 comes up after link

On Mon, Feb 10, 2020 at 06:08:16PM -0600, Bjorn Helgaas wrote:
> used ctrl_info() instead of pci_info() (I would actually like to change
> the whole driver to use pci_info(), but better to be consistent for now)

Most of the ctrl_info() calls prepend "Slot(%s): " to the message.
However that prefix can only be used once pci_hp_initialize() has
been called.

It would probably make sense to change ctrl_info() to always
include the prefix and change those invocations of ctrl_info()
which happen when the slot is not yet or no longer registered,
to pci_info().


> @@ -930,7 +940,7 @@ struct controller *pcie_init(struct pcie_device *dev)
>  		PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_CC |
>  		PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC);
>  
> -	ctrl_info(ctrl, "Slot #%d AttnBtn%c PwrCtrl%c MRL%c AttnInd%c PwrInd%c HotPlug%c Surprise%c Interlock%c NoCompl%c LLActRep%c%s\n",
> +	ctrl_info(ctrl, "Slot #%d AttnBtn%c PwrCtrl%c MRL%c AttnInd%c PwrInd%c HotPlug%c Surprise%c Interlock%c NoCompl%c IbPresDis%c LLActRep%c%s\n",
>  		(slot_cap & PCI_EXP_SLTCAP_PSN) >> 19,
>  		FLAG(slot_cap, PCI_EXP_SLTCAP_ABP),
>  		FLAG(slot_cap, PCI_EXP_SLTCAP_PCP),
> @@ -941,19 +951,10 @@ struct controller *pcie_init(struct pcie_device *dev)
>  		FLAG(slot_cap, PCI_EXP_SLTCAP_HPS),
>  		FLAG(slot_cap, PCI_EXP_SLTCAP_EIP),
>  		FLAG(slot_cap, PCI_EXP_SLTCAP_NCCS),
> +		ctrl->inband_presence_disabled,
>  		FLAG(link_cap, PCI_EXP_LNKCAP_DLLLARC),
>  		pdev->broken_cmd_compl ? " (with Cmd Compl erratum)" : "");

I've just reviewed the resulting commits on pci/hotplug once more and
think there's a small issue here:  If ctrl->inband_presence_disabled is 0,
the string will contain ASCII character 0 (end of string) and if it's 1
it will contain ASCII character 1 (start of header).  A possible solution
would be FLAG(ctrl->inband_presence_disabled, 1).

(The real solution would probably to have a printk format for this kind
of thing.)

Thanks,

Lukas