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 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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