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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
Merge tag 'backlight-next-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight
Pull backlight updates from Lee Jones:
"Fix-ups:
- Improve bootloader/kernel device handover
Bug Fixes:
- Stabilise backlight in ktd253 driver"
* tag 'backlight-next-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
backlight: pwm_bl: Improve bootloader/kernel device handover
backlight: ktd253: Stabilize backlight
+83
-46
+55
-20
drivers/video/backlight/ktd253-backlight.c
+55
-20
drivers/video/backlight/ktd253-backlight.c
···
25
25
26
26
#define KTD253_T_LOW_NS (200 + 10) /* Additional 10ns as safety factor */
27
27
#define KTD253_T_HIGH_NS (200 + 10) /* Additional 10ns as safety factor */
28
+
#define KTD253_T_OFF_CRIT_NS 100000 /* 100 us, now it doesn't look good */
28
29
#define KTD253_T_OFF_MS 3
29
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31
struct ktd253_backlight {
···
35
34
u16 ratio;
36
35
};
37
36
37
+
static void ktd253_backlight_set_max_ratio(struct ktd253_backlight *ktd253)
38
+
{
39
+
gpiod_set_value_cansleep(ktd253->gpiod, 1);
40
+
ndelay(KTD253_T_HIGH_NS);
41
+
/* We always fall back to this when we power on */
42
+
}
43
+
44
+
static int ktd253_backlight_stepdown(struct ktd253_backlight *ktd253)
45
+
{
46
+
/*
47
+
* These GPIO operations absolutely can NOT sleep so no _cansleep
48
+
* suffixes, and no using GPIO expanders on slow buses for this!
49
+
*
50
+
* The maximum number of cycles of the loop is 32 so the time taken
51
+
* should nominally be:
52
+
* (T_LOW_NS + T_HIGH_NS + loop_time) * 32
53
+
*
54
+
* Architectures do not always support ndelay() and we will get a few us
55
+
* instead. If we get to a critical time limit an interrupt has likely
56
+
* occured in the low part of the loop and we need to restart from the
57
+
* top so we have the backlight in a known state.
58
+
*/
59
+
u64 ns;
60
+
61
+
ns = ktime_get_ns();
62
+
gpiod_set_value(ktd253->gpiod, 0);
63
+
ndelay(KTD253_T_LOW_NS);
64
+
gpiod_set_value(ktd253->gpiod, 1);
65
+
ns = ktime_get_ns() - ns;
66
+
if (ns >= KTD253_T_OFF_CRIT_NS) {
67
+
dev_err(ktd253->dev, "PCM on backlight took too long (%llu ns)\n", ns);
68
+
return -EAGAIN;
69
+
}
70
+
ndelay(KTD253_T_HIGH_NS);
71
+
return 0;
72
+
}
73
+
38
74
static int ktd253_backlight_update_status(struct backlight_device *bl)
39
75
{
40
76
struct ktd253_backlight *ktd253 = bl_get_data(bl);
41
77
int brightness = backlight_get_brightness(bl);
42
78
u16 target_ratio;
43
79
u16 current_ratio = ktd253->ratio;
44
-
unsigned long flags;
80
+
int ret;
45
81
46
82
dev_dbg(ktd253->dev, "new brightness/ratio: %d/32\n", brightness);
47
83
···
100
62
}
101
63
102
64
if (current_ratio == 0) {
103
-
gpiod_set_value_cansleep(ktd253->gpiod, 1);
104
-
ndelay(KTD253_T_HIGH_NS);
105
-
/* We always fall back to this when we power on */
65
+
ktd253_backlight_set_max_ratio(ktd253);
106
66
current_ratio = KTD253_MAX_RATIO;
107
67
}
108
68
109
-
/*
110
-
* WARNING:
111
-
* The loop to set the correct current level is performed
112
-
* with interrupts disabled as it is timing critical.
113
-
* The maximum number of cycles of the loop is 32
114
-
* so the time taken will be (T_LOW_NS + T_HIGH_NS + loop_time) * 32,
115
-
*/
116
-
local_irq_save(flags);
117
69
while (current_ratio != target_ratio) {
118
70
/*
119
71
* These GPIO operations absolutely can NOT sleep so no
120
72
* _cansleep suffixes, and no using GPIO expanders on
121
73
* slow buses for this!
122
74
*/
123
-
gpiod_set_value(ktd253->gpiod, 0);
124
-
ndelay(KTD253_T_LOW_NS);
125
-
gpiod_set_value(ktd253->gpiod, 1);
126
-
ndelay(KTD253_T_HIGH_NS);
127
-
/* After 1/32 we loop back to 32/32 */
128
-
if (current_ratio == KTD253_MIN_RATIO)
75
+
ret = ktd253_backlight_stepdown(ktd253);
76
+
if (ret == -EAGAIN) {
77
+
/*
78
+
* Something disturbed the backlight setting code when
79
+
* running so we need to bring the PWM back to a known
80
+
* state. This shouldn't happen too much.
81
+
*/
82
+
gpiod_set_value_cansleep(ktd253->gpiod, 0);
83
+
msleep(KTD253_T_OFF_MS);
84
+
ktd253_backlight_set_max_ratio(ktd253);
129
85
current_ratio = KTD253_MAX_RATIO;
130
-
else
86
+
} else if (current_ratio == KTD253_MIN_RATIO) {
87
+
/* After 1/32 we loop back to 32/32 */
88
+
current_ratio = KTD253_MAX_RATIO;
89
+
} else {
131
90
current_ratio--;
91
+
}
132
92
}
133
-
local_irq_restore(flags);
134
93
ktd253->ratio = current_ratio;
135
94
136
95
dev_dbg(ktd253->dev, "new ratio set to %d/32\n", target_ratio);
+28
-26
drivers/video/backlight/pwm_bl.c
+28
-26
drivers/video/backlight/pwm_bl.c
···
409
409
static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
410
410
{
411
411
struct device_node *node = pb->dev->of_node;
412
+
bool active = true;
413
+
414
+
/*
415
+
* If the enable GPIO is present, observable (either as input
416
+
* or output) and off then the backlight is not currently active.
417
+
* */
418
+
if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
419
+
active = false;
420
+
421
+
if (!regulator_is_enabled(pb->power_supply))
422
+
active = false;
423
+
424
+
if (!pwm_is_enabled(pb->pwm))
425
+
active = false;
426
+
427
+
/*
428
+
* Synchronize the enable_gpio with the observed state of the
429
+
* hardware.
430
+
*/
431
+
if (pb->enable_gpio)
432
+
gpiod_direction_output(pb->enable_gpio, active);
433
+
434
+
/*
435
+
* Do not change pb->enabled here! pb->enabled essentially
436
+
* tells us if we own one of the regulator's use counts and
437
+
* right now we do not.
438
+
*/
412
439
413
440
/* Not booted with device tree or no phandle link to the node */
414
441
if (!node || !node->phandle)
···
447
420
* assume that another driver will enable the backlight at the
448
421
* appropriate time. Therefore, if it is disabled, keep it so.
449
422
*/
450
-
451
-
/* if the enable GPIO is disabled, do not enable the backlight */
452
-
if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
453
-
return FB_BLANK_POWERDOWN;
454
-
455
-
/* The regulator is disabled, do not enable the backlight */
456
-
if (!regulator_is_enabled(pb->power_supply))
457
-
return FB_BLANK_POWERDOWN;
458
-
459
-
/* The PWM is disabled, keep it like this */
460
-
if (!pwm_is_enabled(pb->pwm))
461
-
return FB_BLANK_POWERDOWN;
462
-
463
-
return FB_BLANK_UNBLANK;
423
+
return active ? FB_BLANK_UNBLANK: FB_BLANK_POWERDOWN;
464
424
}
465
425
466
426
static int pwm_backlight_probe(struct platform_device *pdev)
···
499
485
ret = PTR_ERR(pb->enable_gpio);
500
486
goto err_alloc;
501
487
}
502
-
503
-
/*
504
-
* If the GPIO is not known to be already configured as output, that
505
-
* is, if gpiod_get_direction returns either 1 or -EINVAL, change the
506
-
* direction to output and set the GPIO as active.
507
-
* Do not force the GPIO to active when it was already output as it
508
-
* could cause backlight flickering or we would enable the backlight too
509
-
* early. Leave the decision of the initial backlight state for later.
510
-
*/
511
-
if (pb->enable_gpio &&
512
-
gpiod_get_direction(pb->enable_gpio) != 0)
513
-
gpiod_direction_output(pb->enable_gpio, 1);
514
488
515
489
pb->power_supply = devm_regulator_get(&pdev->dev, "power");
516
490
if (IS_ERR(pb->power_supply)) {