tree c2451801c18faea4eb4c5331b1ca6df2e1a0617d
parent 2cf27aadde5bb1736426972c7e8f3ea3a389c345
author Takashi Iwai <tiwai@suse.de> 1422982283 +0100
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> 1423180566 +0000

FROMLIST: BACKPORT: drm/cirrus: Limit modes depending on bpp option

The commit [8975626ea35a: drm/cirrus: allow 32bpp framebuffers for
cirrus drm] broke X modesetting driver because cirrus driver still
provides the full list of modes up to 1280x1024 while the 32bpp can
support only up to 800x600.

We might be able to filter out the invalid modes in mode_valid
callback, but unfortunately the bpp in question can't be referred
there for now (let me know if there is a better way to retrieve the
bpp for the probed fb).

So, instead, this patch adds the bpp module option to specify the
maximal bpp explicitly and limits the resolutions in get_modes
depending on its value.

The default value is set to 24 so that the existing stuff keeps
working.  If you need a new 32bpp feature, specify cirrus.bpp=32
option explicitly.

Fixes: 897i5626ea35a ('drm/cirrus: allow 32bpp framebuffers for cirrus drm')

---
When I backported this, I set the default to 32bpp.

BUG=None
TEST=In a VM `modetest -M cirrus` returns modes 800x600 and below

(am from http://lists.freedesktop.org/archives/dri-devel/2015-February/076829.html)
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Zach Reizner <zachr@chromium.org>
Change-Id: Id7073b8235e98d71ec7a1c41cd2956495ac56552
Reviewed-on: https://chromium-review.googlesource.com/246600
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>