Hi,
Several years ago, I started a thread about stability issues with hp zx1 chipset and ATI FireGL X1 graphics adapter on ia64 platform [1]. As an attempt to minimize problems, a quirk was introduced to restrict AGP mode to 2x [2]. This never solve the stability issues, as the real cause was in fact incorrect settings of the selectable timer interrupt frequency [3].
The attached patch thus removes the useless restriction on AGP mode. Indeed, I'm running at full AGP 4x mode for several weeks now without a problem.
The attached patch applies cleanly against 3.15-rc5.
Thanks,
Émeric
[1] http://marc.info/?l=dri-devel&m=126494456828755&w=2 [2] http://cgit.freedesktop.org/xorg/driver/xf86-video-ati/commit/?id=a7f465f733... [3] http://marc.info/?l=linux-ia64&m=140077543819871&w=2