mactel-support team mailing list archive

[Mario Schwalbe <schwalbe@xxxxxxxxxxxxxxxxx>]

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Hi,

adamhorden@xxxxxxxxxxxxxx schrieb:
> Do you want me to update the following packages for Januty in the PPA:
> 
> mbp-nvidia-bl-dkms
> nvidia-bl-dkms

both nvidia backlight packages are already available for jaunty. i updated
them last week while upgrading to jaunty.

to explain the differences of those packages:

(1) mbp_nvidia_bl: is an Apple specific driver that uses Apple's firmware interface
    to adjust brightness. this mechanism is known to be present on all recent Apple
    machines, including those with Intel and ATI graphics. however it doesn't support
    all machines, because only a few are listed in its device table. the driver has
    been accepted upstream, but the PPA version naturally is somewhat newer.

    pros:
        * auto-loading works (as of Jaunty) unless blacklisted

    almost completely superseded by nvidia_bl due to the following
    drawbacks:
        * only 16 levels (0-15) available
        * lowest level 1 is at approx. 15% brightness which is too bright at night
          and drains more power than necessary
        * buggy firmware, that sometimes - in particular after resuming from suspend
          or rebooting - doesn't reflect to current state
        * for some unknown reasons doesn't work on the MacBook 5 and MacBook Air 2
          if using Nvidia's proprietary graphics driver. switching to a text console
          or using the open-source 'solves' this problems.

(2) nvidia_bl: complete new driver which drives the graphics adapter's smartdimmer
    registers directly, and hence, does only work on machines with Nvidia graphics
    (not necessarily Apple machines). due to its hackish design - it maps the graphics
    adapters registers without registering itself properly to not conflict with the
    actual driver - it is not yet upstream and most likely never will.

    pros:
	* supports more machines not just Apple ones
        * 32 (NV4x chips) or 1024 (NV5x chips) distinct brightness levels
        * no buggy firmware that has to be worked around
    cons:
	* no auto-loading
        * for some unknown reasons doesn't work on the MacBook Pro 5

since no one is in all cases better that the other, there are 2 drivers right now.
unless you have a MacBook Pro 5 where mbp_nvidia_bl is the only working driver, i'd
suggest to prefer nvidia_bl over mbp_nvidia_bl.

ciao,
Mario

- --
 Wo das Chaos auf die Ordnung trifft, gewinnt meist das Chaos,
 weil es besser organisiert ist.
     - Friedrich Nietzsche -

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