Nouveau - Sep 2012 - [Bug 55412] New: Screen turns black during boot after driver tries to set mode on NV50

https://bugs.freedesktop.org/show_bug.cgi?id=55412

          Priority: medium
            Bug ID: 55412
          Assignee: nouveau at lists.freedesktop.org
           Summary: Screen turns black during boot after driver tries to
                    set mode on NV50
        QA Contact: xorg-team at lists.x.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: lubosz at gmail.com
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: git
         Component: Driver/nouveau
           Product: xorg

Created attachment 67816
  --> https://bugs.freedesktop.org/attachment.cgi?id=67816&action=edit
kernel log without flags

The following commit on current nouveau git master breaks setting a valid
resolution at boot and results in a black screen.

commit 97d6852410a83e413d85649cb2cc10e17d6ee2ab
Author: Ben Skeggs <bskeggs at redhat.com>
Date:   Thu Jul 26 08:51:21 2012 +1000

    drm/nouveau/acpi: move definitions out of nouveau_drv.h

    Signed-off-by: Ben Skeggs <bskeggs at redhat.com>

An interesting thing about this bug is that it can be avoided with adding the
kernel flag nouveau.reg_debug=0x600. With this flag a wrong resolution is set
at boot and the screen does not turn black. The X Server cannot start anyway.

My native resolution is 1366x768. GRUB_GFXMODE is 1360x768x32, since the
greater resolution is not listed in grub's vbeinfo.
nouveau and blob run X with 1366x768.

I will attach a log with and without the flag at commit
97d6852410a83e413d85649cb2cc10e17d6ee2ab.

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https://bugs.freedesktop.org/show_bug.cgi?id=55412

--- Comment #1 from Lubosz Sarnecki <lubosz at gmail.com> ---
Created attachment 67817
  --> https://bugs.freedesktop.org/attachment.cgi?id=67817&action=edit
kernel log with nouveau.reg_debug=0x600

Booted with the flag nouveau.reg_debug=0x600.

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--- Comment #2 from Lubosz Sarnecki <lubosz at gmail.com> ---
I guess this can be closed, since it does not occur on Linux 3.6.6, which is
more recent than the mentioned git version.

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--- Comment #3 from Emil Velikov <emil.l.velikov at gmail.com> ---
Hi Lubosz

The commit mentioned was part of the big nouveau rework, that landed in the 3.7
kernel tree. Note that the commit has been rebased thus I cannot check why
exactly it's causing issues with your system
>From what I can see is
* With the offending commit, nouveau fails to detect any CRTC (outputs)
connected, thus the issue
* With the commit and "nouveau.reg_debug=0x600" nouveau complains
"nouveau: `0x600' invalid for parameter `reg_debug" and does not
load (at least
not mentioned in the log)

Can you try the latest nouveau git or linux 3.7 to establish it this regression
has been fixed or not

Thanks

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--- Comment #4 from m.b.lankhorst at gmail.com ---
Very easy to see what regressed, though..

upstream commit that made it to mainline is c0077061e7ea, with this:

     if (nv_encoder->dcb->lvdsconf.use_acpi_for_edid) {
-        if (!nouveau_acpi_edid(dev, connector)) {
+        if (!(nv_connector->edid = nouveau_acpi_edid(dev, connector))) {
             status = connector_status_connected;
             goto out;
         }

Which looks fine, but is inversion of logic. First it returned 0 on success,
now it returns NULL on failure.. Fix would presumably be one line only:

-        if (!(nv_connector->edid = nouveau_acpi_edid(dev, connector))) {
+        if ((nv_connector->edid = nouveau_acpi_edid(dev, connector))) {

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Maarten Lankhorst <m.b.lankhorst at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|nouveau at lists.freedesktop.o |m.b.lankhorst at gmail.com
                   |rg                          |

--- Comment #5 from Maarten Lankhorst <m.b.lankhorst at gmail.com> ---
http://lists.freedesktop.org/archives/dri-devel/2012-November/030048.html

Patch sent.

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