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Date:	Sat, 1 Nov 2008 11:51:52 -0600
From:	Grant Grundler <grundler@...isc-linux.org>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	linux-pci@...r.kernel.org, kristen.c.accardi@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Add option to passively listen for PCIE hotplug events

On Wed, Oct 29, 2008 at 08:09:03PM +0000, Matthew Garrett wrote:
> Various pieces of hardware (such as the Acer Aspire One and Asus EEE) 
> use PCIE hotplug to change the state of devices in response to events 
> such as the removal of SD cards or disabling the wireless radio. 
> However, they do not provide firmware support for this. As a consequence 
> pciehp will refuse to load and various things break.
> 
> The existing workaround has been to use the pciehp_force option. This is 
> undesirable as there is little guarantee that manipulating the power 
> file in the slot directory will actually result in anything happening, 
> leading to potential user confusion and hardware damage. This patch adds 
> a new option, pciehp_passive. In this configuration pciehp will listen 
> for events and notify the PCI core appropriately. However, it will not 
> provide any user controllable sysfs attributes and so the risk of 
> confusion or damage is averted. Any system slots that do have firmware 
> support will continue to provide full functionality.
> 
> Signed-off-by: Matthew Garrett <mjg@...hat.com>

Can you add something to Documentation/ for this new option?
Either kernel-parameters.txt or something in PCI/ seems appropriate.

Just cutting/pasting the above would be good enough for me.

thanks,
grant

> 
> ---
> 
> diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
> index 4b23bc3..b878432 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -41,6 +41,7 @@ int pciehp_debug;
>  int pciehp_poll_mode;
>  int pciehp_poll_time;
>  int pciehp_force;
> +int pciehp_passive;
>  struct workqueue_struct *pciehp_wq;
>  
>  #define DRIVER_VERSION	"0.4"
> @@ -55,10 +56,12 @@ module_param(pciehp_debug, bool, 0644);
>  module_param(pciehp_poll_mode, bool, 0644);
>  module_param(pciehp_poll_time, int, 0644);
>  module_param(pciehp_force, bool, 0644);
> +module_param(pciehp_passive, bool, 0644);
>  MODULE_PARM_DESC(pciehp_debug, "Debugging mode enabled or not");
>  MODULE_PARM_DESC(pciehp_poll_mode, "Using polling mechanism for hot-plug events or not");
>  MODULE_PARM_DESC(pciehp_poll_time, "Polling mechanism frequency, in seconds");
>  MODULE_PARM_DESC(pciehp_force, "Force pciehp, even if _OSC and OSHP are missing");
> +MODULE_PARM_DESC(pciehp_passive, "Listen for pciehp events, even if _OSC and OSHP are missing");
>  
>  #define PCIE_MODULE_NAME "pciehp"
>  
> @@ -85,6 +88,13 @@ static struct hotplug_slot_ops pciehp_hotplug_slot_ops = {
>    	.get_cur_bus_speed =	get_cur_bus_speed,
>  };
>  
> +static struct hotplug_slot_ops pciehp_passive_hotplug_slot_ops = {
> +	.owner =		THIS_MODULE,
> +	.get_adapter_status =	get_adapter_status,
> +  	.get_max_bus_speed =	get_max_bus_speed,
> +  	.get_cur_bus_speed =	get_cur_bus_speed,
> +};
> +
>  /*
>   * Check the status of the Electro Mechanical Interlock (EMI)
>   */
> @@ -212,7 +222,11 @@ static int init_slots(struct controller *ctrl)
>  		hotplug_slot->info = info;
>  		hotplug_slot->private = slot;
>  		hotplug_slot->release = &release_slot;
> -		hotplug_slot->ops = &pciehp_hotplug_slot_ops;
> +		if (pciehp_passive &&
> +		    pciehp_get_hp_hw_control_from_firmware(ctrl->pci_dev))
> +			hotplug_slot->ops = &pciehp_passive_hotplug_slot_ops;
> +		else
> +			hotplug_slot->ops = &pciehp_hotplug_slot_ops;
>  		slot->hotplug_slot = hotplug_slot;
>  		snprintf(name, SLOT_NAME_SIZE, "%u", slot->number);
>  
> @@ -407,7 +421,7 @@ static int pciehp_probe(struct pcie_device *dev, const struct pcie_port_service_
>  	u8 value;
>  	struct pci_dev *pdev = dev->port;
>  
> -	if (pciehp_force)
> +	if (pciehp_force || pciehp_passive)
>  		dev_info(&dev->device,
>  			 "Bypassing BIOS check for pciehp use on %s\n",
>  			 pci_name(pdev));
> @@ -435,7 +449,7 @@ static int pciehp_probe(struct pcie_device *dev, const struct pcie_port_service_
>  	t_slot = pciehp_find_slot(ctrl, ctrl->slot_device_offset);
>  
>  	t_slot->hpc_ops->get_adapter_status(t_slot, &value); /* Check if slot is occupied */
> -	if (value && pciehp_force) {
> +	if (value && (pciehp_force || pciehp_passive)) {
>  		rc = pciehp_enable_slot(t_slot);
>  		if (rc)	/* -ENODEV: shouldn't happen, but deal with it */
>  			value = 0;
> @@ -474,7 +488,7 @@ static int pciehp_suspend (struct pcie_device *dev, pm_message_t state)
>  static int pciehp_resume (struct pcie_device *dev)
>  {
>  	dev_info(&dev->device, "%s ENTRY\n", __func__);
> -	if (pciehp_force) {
> +	if (pciehp_force || pciehp_passive) {
>  		struct controller *ctrl = get_service_data(dev);
>  		struct slot *t_slot;
>  		u8 status;
> 
> -- 
> Matthew Garrett | mjg59@...f.ucam.org
> --
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