linux-kernel - Re: [PATCH v1 4/9] PCI/portdrv: Disable port driver in compat mode

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Message-ID: <38992036.3QHJjk5T7c@aspire.rjw.lan>
Date:   Wed, 07 Mar 2018 11:29:15 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, Keith Busch <keith.busch@...el.com>,
        Sinan Kaya <okaya@...eaurora.org>,
        Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH v1 4/9] PCI/portdrv: Disable port driver in compat mode

On Wednesday, March 7, 2018 7:13:45 AM CET Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> The "pcie_ports=compat" kernel parameter sets pcie_ports_disabled, which is
> intended to disable the PCIe port driver.  But even when it was disabled,
> we registered pcie_portdriver so we could work around a BIOS PME issue (see
> fe31e69740ed ("PCI/PCIe: Clear Root PME Status bits early during system
> resume")).
> 
> Registering the driver meant that the pcie_portdrv_probe() path called
> pci_enable_device(), pci_save_state(), pm_runtime_set_autosuspend_delay(),
> pm_runtime_use_autosuspend(), etc., even when the driver was disabled.
> 
> We've since moved the BIOS PME workaround from the port driver to the core,
> so stop registering the PCIe port driver in compat mode.
> 
> This means "pcie_ports=compat" will now be basically the same as turning
> off CONFIG_PCIEPORTBUS completely.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  drivers/pci/pcie/portdrv_core.c |    3 ---
>  drivers/pci/pcie/portdrv_pci.c  |    2 +-
>  2 files changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
> index ef3bad4ad010..9db77c683732 100644
> --- a/drivers/pci/pcie/portdrv_core.c
> +++ b/drivers/pci/pcie/portdrv_core.c
> @@ -212,9 +212,6 @@ static int get_port_device_capability(struct pci_dev *dev)
>  	int services = 0;
>  	int cap_mask = 0;
>  
> -	if (pcie_ports_disabled)
> -		return 0;
> -
>  	cap_mask = PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP
>  			| PCIE_PORT_SERVICE_VC;
>  	if (pci_aer_available())
> diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
> index f91afd09e356..c08ebd237242 100644
> --- a/drivers/pci/pcie/portdrv_pci.c
> +++ b/drivers/pci/pcie/portdrv_pci.c
> @@ -262,7 +262,7 @@ static int __init pcie_portdrv_init(void)
>  	int retval;
>  
>  	if (pcie_ports_disabled)
> -		return pci_register_driver(&pcie_portdriver);
> +		return -EACCES;
>  
>  	dmi_check_system(pcie_portdrv_dmi_table);
>  
> 
> 

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>