All of lore.kernel.org
 help / color / mirror / Atom feed
From: Aaron Sowry <aaron-+1tCnOwpXBmzQB+pC5nmwQ@public.gmane.org>
To: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
Subject: NV50 backlight brightness
Date: Tue, 19 Oct 2010 11:10:30 +0200	[thread overview]
Message-ID: <20101019091030.GA28588@aeneby.se> (raw)


[-- Attachment #1.1: Type: text/plain, Size: 1117 bytes --]

Hi,

The NV50 codepath in nouveau_backlight.c invariably sets max_brightness to 1025, regardless of the chipset in question. The maximum brightness is not 1025 for all NV50 chipsets (for example, by setting the brightness via ACPI controls and peeking the brightness register, I find that the maximum brightness level for my a8 card is 0x4001df67 although I am unsure of the significance of the MSB).

This means when anything manipulates the backlight using nouveau controls (in my case, usually g-p-m), I get very low backlight brightnesses. 2 questions:

1) Is this a known problem, and has it been looked at before? My affected laptop is a ThinkPad and I know that some Macbooks are also affected, so I would be surprised if it isn't fairly common.

2) In the absence of a reliable way to determine a card's max_brightness by peeking registers or similar, is some kind of mapping table in the code an acceptable solution for assigning max_brightness values to certain chipsets?

This has been discussed at some length on the RedHat bugzilla here:
https://bugzilla.redhat.com/show_bug.cgi?id=625171

Cheers,
Aaron

[-- Attachment #1.2: Digital signature --]
[-- Type: application/pgp-signature, Size: 489 bytes --]

[-- Attachment #2: Type: text/plain, Size: 181 bytes --]

_______________________________________________
Nouveau mailing list
Nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
http://lists.freedesktop.org/mailman/listinfo/nouveau

             reply	other threads:[~2010-10-19  9:10 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-19  9:10 Aaron Sowry [this message]
     [not found] ` <20101019091030.GA28588-+1tCnOwpXBmzQB+pC5nmwQ@public.gmane.org>
2010-10-20 11:17   ` NV50 backlight brightness Ben Skeggs
2010-10-21  9:16     ` Aaron Sowry
     [not found]       ` <20101021091621.GA29567-+1tCnOwpXBmzQB+pC5nmwQ@public.gmane.org>
2010-10-21 10:45         ` Ben Skeggs
2010-10-22  9:57           ` Aaron Sowry
     [not found]             ` <20101022095740.GA30072-+1tCnOwpXBmzQB+pC5nmwQ@public.gmane.org>
2010-10-22 11:17               ` Ben Skeggs
     [not found]                 ` <FC457B53-D6EF-48DC-BB56-F2FAC3D84577-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-10-22 11:51                   ` Aaron Sowry

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20101019091030.GA28588@aeneby.se \
    --to=aaron-+1tcnowpxbmzqb+pc5nmwq@public.gmane.org \
    --cc=nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.