Messages in this thread |  | | | Date | Sun, 18 Mar 2012 12:06:18 +0100 | | From | Lars-Peter Clausen <> | | Subject | Re: [PATCH v2 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register |
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On 03/17/2012 01:07 AM, Axel Lin wrote: > The datasheet says 00000000 to 00101110 are reserved, and the min value of the > voltage setting is 1.8 V. > Thus don't write 0 to AUTO output voltage select register (address 1Ah). > > Table 50. AUTOOUT - AUTO output voltage select register (address 1Ah) bit description[1] > Bit Symbol Access Description > 7:0 auto_out R/W VO(prog) = 0.625 + auto_out × 0.025 V > eg. 00000000 to 00101110: reserved > 00101111: 1.8 V (min) > 01010011: 2.7 V > 01101010: 3.275 V > 01101011: 3.300 V > 01101100: 3.325 V > 01111111 : 3.800 V (max) > ..... ..... > 11111110 : 3.800 V > 11111111 : 3.800 V > > This patch also fixes a bug in pcf50633_regulator_list_voltage. > It is wrong to do "index += 0x2f" for PCF50633_REGULATOR_AUTO in > pcf50633_regulator_list_voltage. The purpose of adding 0x2f to index is because > current code return 0 in auto_voltage_bits when millivolts < 1800. > For millivolts > 1800, adding 0x2f to index is wrong. >
I think you misunderstood what the current code does. The first usable voltage is 1.8V which is equal to a index of of 0x2f. So the driver adds 0x2f to the index so that there is not a headroom of 0x2f unusable voltages. So a selector of 0 translates to 1.8V, a selector of 1 translates to 1.825V and so on.
I can see why you'd want to change it to simplify the code, but you also have to change the number of voltages for the AUTO regulator to 128. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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