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Date: Mon, 19 Dec 2016 01:05:10 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Lukas Wunner <lukas@...ner.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Andreas Noever <andreas.noever@...il.com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
Tomas Winkler <tomas.winkler@...el.com>,
Amir Levy <amir.jer.levy@...el.com>
Subject: Re: [PATCH v3 6/7] thunderbolt: Power down controller when idle
On Sat, Dec 17, 2016 at 4:39 PM, Lukas Wunner <lukas@...ner.de> wrote:
> Document and implement Apple's ACPI-based (but nonstandard) pm mechanism
> for Thunderbolt. Briefly, an ACPI method provided by Apple is used to
> cut power to the controller. A GPE is enabled while the controller is
> powered down which sideband-signals a plug event, whereupon we reinstate
> power using the ACPI method.
>
> This saves 1.7 W on machines with a Light Ridge controller and is
> reported to save 4 W on Cactus Ridge 4C and Falcon Ridge 4C. (I believe
> 4 W includes the bus power drawn by Apple's Gigabit Ethernet adapter.)
> It fixes (at least partially) a power regression introduced in 3.17 by
> commit 7bc5a2bad0b8 ("ACPI: Support _OSI("Darwin") correctly").
>
> +++ b/drivers/thunderbolt/power.c
> @@ -0,0 +1,347 @@
> +#include <linux/delay.h>
> +#include <linux/pci.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "power.h"
> +
> +#ifdef pr_fmt
> +#undef pr_fmt
> +#endif
Perhaps just define pr_fmt before any other include?
We have such check where actually default pr_fmt is defined. No need
to duplicate.
> +#define pr_fmt(fmt) KBUILD_MODNAME " %s: " fmt, dev_name(dev)
> +
> + /* prevent interrupts during system sleep transition */
> + if (ACPI_FAILURE(acpi_disable_gpe(NULL, power->wake_gpe))) {
> + pr_err("cannot disable wake GPE, resuming\n");
dev_err?
> + pm_request_resume(dev);
> + return -EAGAIN;
> + }
> +
> + return DPM_DIRECT_COMPLETE;
> +}
> + pr_info("resetting power switch\n");
> + if (ACPI_FAILURE(acpi_execute_simple_method(power->set, NULL, 0))) {
> + pr_err("cannot call power->set method\n");
> + dev->power.runtime_error = -EIO;
> + }
> +
> + if (ACPI_FAILURE(acpi_enable_gpe(NULL, power->wake_gpe))) {
> + pr_err("cannot enable wake GPE, resuming\n");
> + pm_request_resume(dev);
> + }
Ditto. pr_ -> dev_ ?
Also in the rest of code where applicable.
> + /*
> + * On gen 2 controllers, the wake GPE fires as long as the controller
> + * is powered up. Poll until it's powered down before enabling the GPE.
> + */
> + for (i = 0; i < 300; i++) {
300 is magic.
> + if (ACPI_FAILURE(acpi_evaluate_integer(power->get,
> + NULL, NULL, &powered_down))) {
> + pr_err("cannot call power->get method, resuming\n");
> + goto err;
> + }
> + if (powered_down)
> + break;
> + usleep_range(800, 1600);
Why 800? Perhaps comment on this.
> + }
> + if (!powered_down) {
> + pr_err("refused to power down, resuming\n");
> + goto err;
> + }
> +
> + if (ACPI_FAILURE(acpi_enable_gpe(NULL, power->wake_gpe))) {
> + pr_err("cannot enable wake GPE, resuming\n");
> + goto err;
> + }
> +
> + return 0;
> +
> +err:
err_resume: ?
> + acpi_execute_simple_method(power->set, NULL, 1);
> + dev->bus->pm->runtime_resume(dev);
> + pci_walk_bus(pdev->subordinate, request_resume, NULL);
> + return -EAGAIN;
> +}
> +void thunderbolt_power_init(struct tb *tb)
> +{
> + struct device *upstream_dev, *nhi_dev = &tb->nhi->pdev->dev;
> + struct tb_power *power = NULL;
> + struct acpi_handle *nhi_handle;
> +
> + power = kzalloc(sizeof(*power), GFP_KERNEL);
> + if (!power) {
> + dev_err(nhi_dev, "cannot allocate power data\n");
> + goto err;
> + }
> +
> + nhi_handle = ACPI_HANDLE(nhi_dev);
> + if (!nhi_handle) {
> + dev_err(nhi_dev, "cannot find ACPI handle\n");
> + goto err;
> + }
> +
> + /* Macs introduced 2011/2012 have XRPE, 2013+ have TRPE */
> + if (ACPI_FAILURE(acpi_get_handle(nhi_handle, "XRPE", &power->set)) &&
> + ACPI_FAILURE(acpi_get_handle(nhi_handle, "TRPE", &power->set))) {
> + dev_err(nhi_dev, "cannot find power->set method\n");
> + goto err;
> + }
> +
> + if (ACPI_FAILURE(acpi_get_handle(nhi_handle, "XRIL", &power->get))) {
> + dev_err(nhi_dev, "cannot find power->get method\n");
> + goto err;
> + }
> +
> + if (ACPI_FAILURE(acpi_evaluate_integer(nhi_handle, "XRIN", NULL,
> + &power->wake_gpe))) {
> + dev_err(nhi_dev, "cannot find wake GPE\n");
> + goto err;
> + }
> +
> + if (ACPI_FAILURE(acpi_install_gpe_handler(NULL, power->wake_gpe,
> + ACPI_GPE_LEVEL_TRIGGERED, nhi_wake, nhi_dev))) {
> + dev_err(nhi_dev, "cannot install GPE handler\n");
> + goto err;
> + }
> +
> + if (!nhi_dev->parent || !nhi_dev->parent->parent) {
> + dev_err(nhi_dev, "cannot find upstream bridge\n");
> + goto err;
> + }
> + upstream_dev = nhi_dev->parent->parent;
> +
> + pci_walk_bus(to_pci_dev(upstream_dev)->bus, disable_pme_poll,
> + to_pci_dev(upstream_dev)->subordinate);
> +
> + power->pm_domain.ops = *upstream_dev->bus->pm;
> + power->pm_domain.ops.prepare = upstream_prepare;
> + power->pm_domain.ops.complete = upstream_complete;
> + power->pm_domain.ops.runtime_suspend = upstream_runtime_suspend;
> + power->pm_domain.ops.runtime_resume = upstream_runtime_resume;
> + power->tb = tb;
> + dev_pm_domain_set(upstream_dev, &power->pm_domain);
> +
> + tb->power = power;
> +
> + return;
> +
> +err:
err_free: ?
> + dev_err(nhi_dev, "controller will stay powered up permanently\n");
> + kfree(power);
> +}
> +
> +void thunderbolt_power_fini(struct tb *tb)
> +{
> + struct device *nhi_dev = &tb->nhi->pdev->dev;
> + struct device *upstream_dev = nhi_dev->parent->parent;
> + struct tb_power *power = tb->power;
> +
> + if (!power)
> + return;
Would be the case?
> +
> + tb->power = NULL;
> + dev_pm_domain_set(upstream_dev, NULL);
> +
> + if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, power->wake_gpe,
> + nhi_wake)))
> + dev_err(nhi_dev, "cannot remove GPE handler\n");
> +
> + kfree(power);
> +}
--
With Best Regards,
Andy Shevchenko
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