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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id i4-20020a056870044400b000f15ca674b2sm4305696oak.52.2022.05.23.16.34.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 May 2022 16:34:40 -0700 (PDT) From: Bjorn Andersson To: Jonathan Corbet , Pavel Machek , Marijn Suijten Cc: Matthias Kaehlcke , Stephen Boyd , Satya Priya , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: [PATCH] leds: qcom-lpg: Require pattern to follow documentation Date: Mon, 23 May 2022 16:37:19 -0700 Message-Id: <20220523233719.1496297-1-bjorn.andersson@linaro.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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: 24e2d05d1b68 ("leds: Add driver for Qualcomm LPG") Signed-off-by: Bjorn Andersson Reviewed-by: Stephen Boyd --- Documentation/leds/leds-qcom-lpg.rst | 8 ++++-- drivers/leds/rgb/leds-qcom-lpg.c | 43 ++++++++++++++++++++++++---- 2 files changed, 43 insertions(+), 8 deletions(-) diff --git a/Documentation/leds/leds-qcom-lpg.rst b/Documentation/leds/leds= -qcom-lpg.rst index f12416f02dd8..de7ceead9337 100644 --- a/Documentation/leds/leds-qcom-lpg.rst +++ b/Documentation/leds/leds-qcom-lpg.rst @@ -35,11 +35,13 @@ Specify a hardware pattern for a Qualcomm LPG LED. The pattern is a series of brightness and hold-time pairs, with the hold-t= ime expressed in milliseconds. The hold time is a property of the pattern and = must therefor be identical for each element in the pattern (except for the paus= es -described below). +described below). As the LPG hardware is not able to perform the linear +transitions expected by the leds-trigger-pattern format, each entry in the +pattern must be followed a zero-length entry of the same brightness. =20 Simple pattern:: =20 - "255 500 0 500" + "255 500 255 0 0 500 0 0" =20 ^ | @@ -54,7 +56,7 @@ in the pattern, the so called "low pause" and "high pause= ". =20 Low-pause pattern:: =20 - "255 1000 0 500 255 500 0 500" + "255 1000 255 0 0 500 0 0 255 500 255 0 0 500 0 0" =20 ^ | diff --git a/drivers/leds/rgb/leds-qcom-lpg.c b/drivers/leds/rgb/leds-qcom-= lpg.c index cfa3362b2457..02f51cc61837 100644 --- a/drivers/leds/rgb/leds-qcom-lpg.c +++ b/drivers/leds/rgb/leds-qcom-lpg.c @@ -704,11 +704,12 @@ static int lpg_blink_mc_set(struct led_classdev *cdev, return ret; } =20 -static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *patter= n, +static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *led_pa= ttern, u32 len, int repeat) { struct lpg_channel *chan; struct lpg *lpg =3D led->lpg; + struct led_pattern *pattern; unsigned int brightness_a; unsigned int brightness_b; unsigned int actual_len; @@ -719,18 +720,48 @@ static int lpg_pattern_set(struct lpg_led *led, struc= t led_pattern *pattern, unsigned int hi_idx; unsigned int i; bool ping_pong =3D true; - int ret; + int ret =3D -EINVAL; =20 /* Hardware only support oneshot or indefinite loops */ if (repeat !=3D -1 && repeat !=3D 1) return -EINVAL; =20 + /* + * The standardized leds-trigger-pattern format defines that the + * brightness of the LED follows a linear transition from one entry + * in the pattern to the next, over the given delta_t time. It + * describes that the way to perform instant transitions a zero-length + * entry should be added following a pattern entry. + * + * The LPG hardware is only able to perform the latter (no linear + * transitions), so require each entry in the pattern to be followed by + * a zero-length transition. + */ + if (len % 2) + return -EINVAL; + + pattern =3D kcalloc(len / 2, sizeof(*pattern), GFP_KERNEL); + if (!pattern) + return -ENOMEM; + + for (i =3D 0; i < len; i +=3D 2) { + if (led_pattern[i].brightness !=3D led_pattern[i + 1].brightness) + goto out_free_pattern; + if (led_pattern[i + 1].delta_t !=3D 0) + goto out_free_pattern; + + pattern[i / 2].brightness =3D led_pattern[i].brightness; + pattern[i / 2].delta_t =3D led_pattern[i].delta_t; + } + + len /=3D 2; + /* * Specifying a pattern of length 1 causes the hardware to iterate * through the entire LUT, so prohibit this. */ if (len < 2) - return -EINVAL; + goto out_free_pattern; =20 /* * The LPG plays patterns with at a fixed pace, a "low pause" can be @@ -781,13 +812,13 @@ static int lpg_pattern_set(struct lpg_led *led, struc= t led_pattern *pattern, * specify hi pause. Reject other variations. */ if (i !=3D actual_len - 1) - return -EINVAL; + goto out_free_pattern; } } =20 /* LPG_RAMP_DURATION_REG is a 9bit */ if (delta_t >=3D BIT(9)) - return -EINVAL; + goto out_free_pattern; =20 /* Find "low pause" and "high pause" in the pattern */ lo_pause =3D pattern[0].delta_t; @@ -814,6 +845,8 @@ static int lpg_pattern_set(struct lpg_led *led, struct = led_pattern *pattern, =20 out_unlock: mutex_unlock(&lpg->lock); +out_free_pattern: + kfree(pattern); =20 return ret; } --=20 2.35.1