Messages in this thread | | | Date | Mon, 18 Mar 2013 09:26:40 +0100 | From | Danny Baumann <> | Subject | Re: [PATCH v2 3/3] ACPI video: Fix applying indexed initial brightness value. |
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Hi,
>> +static unsigned long long >> +acpi_video_bqc_value_to_level(struct acpi_video_device *device, >> + unsigned long long bqc_value) >> +{ >> + unsigned long long level; >> + >> + if (device->brightness->flags._BQC_use_index) { >> + if (device->brightness->flags._BCL_reversed) >> + bqc_value = device->brightness->count - 3 - bqc_value; >> + >> + level = device->brightness->levels[bqc_value + 2]; > > I don't understand this, what does the +2 have to do here? > _BQC returned us an index, and then we should just convert it to level, > why +2? > > The only explanation would be, for BIOS tables that return _BQC as > index, they are indexing from the 3rd entry. Is it the case? If so, I > think we need to put a comment here.
Yes, that's the case. The old code did the same thing:
>> - if (device->brightness->flags._BQC_use_index) { >> - if (device->brightness->flags._BCL_reversed) >> - *level = device->brightness->count >> - - 3 - (*level); >> - *level = device->brightness->levels[*level + 2]; >> + *level = acpi_video_bqc_value_to_level(device, *level);
That's also the reason for the -3 instead of -1 in the BCL_reversed case. I can add a comment, though.
>> + if (use_bios_initial_backlight) { >> + if (!br->flags._BQC_use_index) { >> + /* >> + * Set the backlight to the initial state. >> + * On some buggy laptops, _BQC returns an uninitialized >> + * value when invoked for the first time, i.e. >> + * level_old is invalid. Set the backlight to max_level >> + * in this case. >> + */ >> for (i = 2; i < br->count; i++) >> if (level_old == br->levels[i]) { >> level = level_old; >> break; >> } >> + } else { >> + level = acpi_video_bqc_value_to_level(device, >> + level_old); > > What about we convert the value to level first? > > if (use_bios_initial_backlight) { > level = acpi_video_bqc_value_to_level(device, level_old); > /* > * Set the backlight to the initial state. > * On some buggy laptops, _BQC returns an uninitialized > * value when invoked for the first time, i.e. > * level_old is invalid(no matter it is a level, or an > * index.) Set the backlight to max_level in this case. > */ > for (i = 2; i < br->count; i++) > if (level == br->levels[i]) > break; > if (i == br->count) > level = max_level; > }
That works as well, and looks cleaner to me as well. I'll change that.
Regards,
Danny
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