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leds: qcom-lpg: Require pattern to follow documentation
The leds-trigger-pattern documentation describes how the brightness of
the LED should transition linearly from one brightness value to the
next, over the given delta_t.
But the pattern engine in the Qualcomm LPG hardware only supports
holding the brightness for each entry for the period.
This subset of patterns can be represented in the leds-trigger-pattern
by injecting zero-time transitions after each entry in the pattern,
resulting in a pattern that pattern that can be rendered by the LPG.
Rework LPG pattern interface to require these zero-time transitions, to
make it comply with this subset of patterns and reject the patterns it
can't render.
Fixes: 24e2d05d1b
("leds: Add driver for Qualcomm LPG")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
This commit is contained in:
parent
73bce575ed
commit
e98a860f65
2 changed files with 43 additions and 8 deletions
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@ -35,11 +35,13 @@ Specify a hardware pattern for a Qualcomm LPG LED.
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The pattern is a series of brightness and hold-time pairs, with the hold-time
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expressed in milliseconds. The hold time is a property of the pattern and must
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therefor be identical for each element in the pattern (except for the pauses
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described below).
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described below). As the LPG hardware is not able to perform the linear
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transitions expected by the leds-trigger-pattern format, each entry in the
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pattern must be followed a zero-length entry of the same brightness.
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Simple pattern::
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"255 500 0 500"
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"255 500 255 0 0 500 0 0"
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^
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@ -54,7 +56,7 @@ in the pattern, the so called "low pause" and "high pause".
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Low-pause pattern::
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"255 1000 0 500 255 500 0 500"
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"255 1000 255 0 0 500 0 0 255 500 255 0 0 500 0 0"
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^
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@ -704,11 +704,12 @@ static int lpg_blink_mc_set(struct led_classdev *cdev,
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return ret;
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}
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static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *pattern,
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static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *led_pattern,
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u32 len, int repeat)
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{
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struct lpg_channel *chan;
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struct lpg *lpg = led->lpg;
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struct led_pattern *pattern;
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unsigned int brightness_a;
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unsigned int brightness_b;
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unsigned int actual_len;
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@ -719,18 +720,48 @@ static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *pattern,
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unsigned int hi_idx;
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unsigned int i;
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bool ping_pong = true;
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int ret;
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int ret = -EINVAL;
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/* Hardware only support oneshot or indefinite loops */
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if (repeat != -1 && repeat != 1)
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return -EINVAL;
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/*
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* The standardized leds-trigger-pattern format defines that the
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* brightness of the LED follows a linear transition from one entry
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* in the pattern to the next, over the given delta_t time. It
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* describes that the way to perform instant transitions a zero-length
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* entry should be added following a pattern entry.
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*
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* The LPG hardware is only able to perform the latter (no linear
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* transitions), so require each entry in the pattern to be followed by
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* a zero-length transition.
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*/
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if (len % 2)
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return -EINVAL;
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pattern = kcalloc(len / 2, sizeof(*pattern), GFP_KERNEL);
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if (!pattern)
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return -ENOMEM;
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for (i = 0; i < len; i += 2) {
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if (led_pattern[i].brightness != led_pattern[i + 1].brightness)
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goto out_free_pattern;
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if (led_pattern[i + 1].delta_t != 0)
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goto out_free_pattern;
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pattern[i / 2].brightness = led_pattern[i].brightness;
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pattern[i / 2].delta_t = led_pattern[i].delta_t;
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}
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len /= 2;
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/*
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* Specifying a pattern of length 1 causes the hardware to iterate
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* through the entire LUT, so prohibit this.
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*/
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if (len < 2)
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return -EINVAL;
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goto out_free_pattern;
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/*
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* The LPG plays patterns with at a fixed pace, a "low pause" can be
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@ -781,13 +812,13 @@ static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *pattern,
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* specify hi pause. Reject other variations.
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*/
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if (i != actual_len - 1)
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return -EINVAL;
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goto out_free_pattern;
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}
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}
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/* LPG_RAMP_DURATION_REG is a 9bit */
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if (delta_t >= BIT(9))
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return -EINVAL;
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goto out_free_pattern;
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/* Find "low pause" and "high pause" in the pattern */
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lo_pause = pattern[0].delta_t;
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@ -814,6 +845,8 @@ static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *pattern,
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out_unlock:
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mutex_unlock(&lpg->lock);
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out_free_pattern:
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kfree(pattern);
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return ret;
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}
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