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Message-ID: <201803192119.WIzt6M4j%fengguang.wu@intel.com>
Date: Mon, 19 Mar 2018 21:53:16 +0800
From: kbuild test robot <lkp@...el.com>
To: Daniel Drake <drake@...lessm.com>
Cc: kbuild-all@...org, rjw@...ysocki.net, lenb@...nel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
linux@...lessm.com, chiu@...lessm.com, mathias.nyman@...el.com,
linux-usb@...r.kernel.org
Subject: Re: [PATCH] ACPI / PM: allow deeper wakeup power states with no _SxD
nor _SxW
Hi Daniel,
I love your patch! Perhaps something to improve:
[auto build test WARNING on v4.16-rc4]
[also build test WARNING on next-20180319]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Daniel-Drake/ACPI-PM-allow-deeper-wakeup-power-states-with-no-_SxD-nor-_SxW/20180319-185209
config: i386-randconfig-x074-201811 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All warnings (new ones prefixed by >>):
drivers/acpi/device_pm.c: In function 'acpi_dev_pm_get_state':
>> drivers/acpi/device_pm.c:607:7: warning: 'sxd_status' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (sxd_status == AE_OK && target_state > ACPI_STATE_S0)
^
vim +/sxd_status +607 drivers/acpi/device_pm.c
516
517 /**
518 * acpi_dev_pm_get_state - Get preferred power state of ACPI device.
519 * @dev: Device whose preferred target power state to return.
520 * @adev: ACPI device node corresponding to @dev.
521 * @target_state: System state to match the resultant device state.
522 * @d_min_p: Location to store the highest power state available to the device.
523 * @d_max_p: Location to store the lowest power state available to the device.
524 *
525 * Find the lowest power (highest number) and highest power (lowest number) ACPI
526 * device power states that the device can be in while the system is in the
527 * state represented by @target_state. Store the integer numbers representing
528 * those stats in the memory locations pointed to by @d_max_p and @d_min_p,
529 * respectively.
530 *
531 * Callers must ensure that @dev and @adev are valid pointers and that @adev
532 * actually corresponds to @dev before using this function.
533 *
534 * Returns 0 on success or -ENODATA when one of the ACPI methods fails or
535 * returns a value that doesn't make sense. The memory locations pointed to by
536 * @d_max_p and @d_min_p are only modified on success.
537 */
538 static int acpi_dev_pm_get_state(struct device *dev, struct acpi_device *adev,
539 u32 target_state, int *d_min_p, int *d_max_p)
540 {
541 char method[] = { '_', 'S', '0' + target_state, 'D', '\0' };
542 acpi_handle handle = adev->handle;
543 unsigned long long ret;
544 int d_min, d_max;
545 bool wakeup = false;
546 acpi_status sxd_status;
547 acpi_status status;
548
549 /*
550 * If the system state is S0, the lowest power state the device can be
551 * in is D3cold, unless the device has _S0W and is supposed to signal
552 * wakeup, in which case the return value of _S0W has to be used as the
553 * lowest power state available to the device.
554 */
555 d_min = ACPI_STATE_D0;
556 d_max = ACPI_STATE_D3_COLD;
557
558 /*
559 * If present, _SxD methods return the minimum D-state (highest power
560 * state) we can use for the corresponding S-states. Otherwise, the
561 * minimum D-state is D0 (ACPI 3.x).
562 */
563 if (target_state > ACPI_STATE_S0) {
564 /*
565 * We rely on acpi_evaluate_integer() not clobbering the integer
566 * provided if AE_NOT_FOUND is returned.
567 */
568 ret = d_min;
569 sxd_status = acpi_evaluate_integer(handle, method, NULL, &ret);
570 if ((ACPI_FAILURE(sxd_status) && sxd_status != AE_NOT_FOUND)
571 || ret > ACPI_STATE_D3_COLD)
572 return -ENODATA;
573
574 /*
575 * We need to handle legacy systems where D3hot and D3cold are
576 * the same and 3 is returned in both cases, so fall back to
577 * D3cold if D3hot is not a valid state.
578 */
579 if (!adev->power.states[ret].flags.valid) {
580 if (ret == ACPI_STATE_D3_HOT)
581 ret = ACPI_STATE_D3_COLD;
582 else
583 return -ENODATA;
584 }
585 d_min = ret;
586 wakeup = device_may_wakeup(dev) && adev->wakeup.flags.valid
587 && adev->wakeup.sleep_state >= target_state;
588 } else {
589 wakeup = adev->wakeup.flags.valid;
590 }
591
592 /*
593 * If _PRW says we can wake up the system from the target sleep state,
594 * the D-state returned by _SxD is sufficient for that (we assume a
595 * wakeup-aware driver if wake is set). Still, if _SxW exists
596 * (ACPI 3.x), it should return the maximum (lowest power) D-state that
597 * can wake the system. _S0W may be valid, too.
598 */
599 if (wakeup) {
600 method[3] = 'W';
601 status = acpi_evaluate_integer(handle, method, NULL, &ret);
602 if (status == AE_NOT_FOUND) {
603 /* No _SxW. In this case, the ACPI spec says that we
604 * must not go into any power state deeper than the
605 * value returned from _SxD.
606 */
> 607 if (sxd_status == AE_OK && target_state > ACPI_STATE_S0)
608 d_max = d_min;
609 } else if (ACPI_SUCCESS(status) && ret <= ACPI_STATE_D3_COLD) {
610 /* Fall back to D3cold if ret is not a valid state. */
611 if (!adev->power.states[ret].flags.valid)
612 ret = ACPI_STATE_D3_COLD;
613
614 d_max = ret > d_min ? ret : d_min;
615 } else {
616 return -ENODATA;
617 }
618 }
619
620 if (d_min_p)
621 *d_min_p = d_min;
622
623 if (d_max_p)
624 *d_max_p = d_max;
625
626 return 0;
627 }
628
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