diff options
| -rw-r--r-- | drivers/gpu/drm/nouveau/core/subdev/therm/fan.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c b/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c index 9ad6e166dd75..b7339b52559e 100644 --- a/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c +++ b/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c @@ -105,30 +105,37 @@ nouveau_therm_fan_sense(struct nouveau_therm *therm) struct nouveau_gpio *gpio = nouveau_gpio(therm); struct dcb_gpio_func func; u32 cycles, cur, prev; - u64 start; + u64 start, end, tach; if (gpio->find(gpio, 0, DCB_GPIO_FAN_SENSE, 0xff, &func)) return -ENODEV; - /* Monitor the GPIO input 0x3b for 250ms. + /* Time a complete rotation and extrapolate to RPM: * When the fan spins, it changes the value of GPIO FAN_SENSE. - * We get 4 changes (0 -> 1 -> 0 -> 1 -> [...]) per complete rotation. + * We get 4 changes (0 -> 1 -> 0 -> 1) per complete rotation. */ start = ptimer->read(ptimer); prev = gpio->get(gpio, 0, func.func, func.line); cycles = 0; do { + usleep_range(500, 1000); /* supports 0 < rpm < 7500 */ + cur = gpio->get(gpio, 0, func.func, func.line); if (prev != cur) { + if (!start) + start = ptimer->read(ptimer); cycles++; prev = cur; } - - usleep_range(500, 1000); /* supports 0 < rpm < 7500 */ - } while (ptimer->read(ptimer) - start < 250000000); - - /* interpolate to get rpm */ - return cycles / 4 * 4 * 60; + } while (cycles < 5 && ptimer->read(ptimer) - start < 250000000); + end = ptimer->read(ptimer); + + if (cycles == 5) { + tach = (u64)60000000000; + do_div(tach, (end - start)); + return tach; + } else + return 0; } static void |