On Thu, Jun 23, 2022 at 07:56:31PM +0800, ChiaEn Wu wrote:
From: ChiaEn Wu chiaen_wu@richtek.com
Add Mediatek MT6370 Backlight support.
Signed-off-by: ChiaEn Wu chiaen_wu@richtek.com
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index a003e02..7cd823d 100644
<snip> +static int mt6370_init_backlight_properties(struct mt6370_priv *priv, + struct backlight_properties *props) +{ + struct device *dev = priv->dev; + u8 prop_val; + u32 brightness, ovp_uV, ocp_uA; + unsigned int mask, val; + int ret; + + /* Vendor optional properties */ + val = 0; + if (device_property_read_bool(dev, "mediatek,bled-pwm-enable")) + val |= MT6370_BL_PWM_EN_MASK; + + if (device_property_read_bool(dev, "mediatek,bled-pwm-hys-enable")) + val |= MT6370_BL_PWM_HYS_EN_MASK; + + ret = device_property_read_u8(dev, + "mediatek,bled-pwm-hys-input-th-steps", + &prop_val); + if (!ret) { + prop_val = clamp_val(prop_val, + MT6370_BL_PWM_HYS_TH_MIN_STEP, + MT6370_BL_PWM_HYS_TH_MAX_STEP); + /* + * prop_val = 1 --> 1 steps --> 0x00 + * prop_val = 2 ~ 4 --> 4 steps --> 0x01 + * prop_val = 5 ~ 16 --> 16 steps --> 0x10 + * prop_val = 17 ~ 64 --> 64 steps --> 0x11
^^^^^ These numbers are binary, not hex, right? If so, the comments should be 0b00 to 0b03 .
*/prop_val = (ilog2(roundup_pow_of_two(prop_val)) + 1) >> 1;val |= prop_val << (ffs(MT6370_BL_PWM_HYS_SEL_MASK) - 1);- }
- ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
val, val);- if (ret)
return ret;
Overall, I like this approach! Easy to read and understand.
<snip> +static int mt6370_bl_probe(struct platform_device *pdev) +{ + struct mt6370_priv *priv; + struct backlight_properties props = { + .type = BACKLIGHT_RAW, + .scale = BACKLIGHT_SCALE_LINEAR,
Sorry, I missed this before but the KConfig comment says that the backlight can support both linear and exponential curves.
Is there a good reason to default to linear?
Daniel.