On 11/27/2015 12:19 PM, Jacek Anaszewski wrote:
Hi Milo, Thanks for the update. I have few comments below.
[...]
+static u8 lm3633_led_scale_max_brightness(struct ti_lmu_led *lmu_led, u32 imax) +{ + u8 max_current = lm3633_led_convert_current_to_index(imax); + const u8 max_brightness_table[] = { + [LMU_IMAX_5mA] = 191, + [LMU_IMAX_6mA] = 197, + [LMU_IMAX_7mA] = 203, + [LMU_IMAX_8mA] = 208, + [LMU_IMAX_9mA] = 212, + [LMU_IMAX_10mA] = 216, + [LMU_IMAX_11mA] = 219, + [LMU_IMAX_12mA] = 222, + [LMU_IMAX_13mA] = 225, + [LMU_IMAX_14mA] = 228, + [LMU_IMAX_15mA] = 230, + [LMU_IMAX_16mA] = 233, + [LMU_IMAX_17mA] = 235, + [LMU_IMAX_18mA] = 237, + [LMU_IMAX_19mA] = 239, + [LMU_IMAX_20mA] = 241, + [LMU_IMAX_21mA] = 242, + [LMU_IMAX_22mA] = 244, + [LMU_IMAX_23mA] = 246, + [LMU_IMAX_24mA] = 247, + [LMU_IMAX_25mA] = 249, + [LMU_IMAX_26mA] = 250, + [LMU_IMAX_27mA] = 251, + [LMU_IMAX_28mA] = 253, + [LMU_IMAX_29mA] = 254, + [LMU_IMAX_30mA] = 255, + };After analyzing the subject one more time I think that we need to change the approach regarding max brightness issue. At first - we shouldn't fix max current to max possible register value. Instead we should take led-max-microamp property and write its value to the [0x22 + bank offset] registers.
It was of course a mental shortcut. The value to write should be calculated by transforming the formula given next to the register documentation: 11111 = 29.8 mA 0.8mA steps, FS = 5mA + code * 0.8 mA code is here the [0x22 + bank_offset] register value. Effectively, the formula to calculate the register value basing on led-max-microamp value should be: FS = led-max-microamp - 5000 / 800 E.g. for 20.2 mA: FS = (20200 - 5000) / 800 = 19 for 29.8 mA: FS = (29800 - 5000) / 800 = 31 for 5 mA: FS = (5000 - 5000) / 800 = 0 From the above min, max and step values for led-max-microamp are 5000, 29800 and 800 respectively. Please correct DT documentation accordingly.
With this approach whole 0-255 range of brightness levels will be valid for the driver. In effect all LMU_IMAX* enums seem to be not needed.
-- Best Regards, Jacek Anaszewski -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
