I think there are two issues here: the first is the missing alignment
workaround, since i'll be upgrading to 3.4.69 anyway i'll insert some
diagnostic messages in radeon_device.c and see what happens. But i'm
pretty certain now that this isn't the cause for the lockups. They are
probably (quite certainly) caused by the dynamic binding/unbinding of
AGP memory which the Uninorth chipset used in 32-bit powermacs obviously
doesn't support. All it supports seems to be statically allocating a 256
MB contigouous non-cacheable AGP aperture and using that (since the
chipset doesn't do any address mapping via the GART as indicated in the
OpenBSD code). So to get AGP mode working again on those machines one
would have to disable the dynamic memory stuff. Question: Would that
require changes in the driver only or also in the DRM ?
Cheers
Jochen
Am 14.11.2013 02:37, schrieb Michel Dänzer:
On Mit, 2013-11-13 at 19:07 +0100, Jochen Rollwagen wrote:
I started investigating the problem because AGP mode used to work with
the UMS drivers (although I now understand they didn’t really use AGP
memory)
They used AGP memory but didn't dynamically bind memory to the AGP
aperture or unbind it from there.
and in the second patch I mentioned below Benjamin Herrenschmidt
stated that “there's a chip errata (for the pre-R600 chips). On those
chips, the aperture must be aligned to the aperture size (that is
FB_START in MC_FB_LOCATION must be aligned to the aperture size).”
Since that workaround/patch definitely isn’t in the current DRM code
any more (probably got lost in the transition to KMS) my idea was to
re-apply the three-line workaround/patch (which should be quite
trivial given the comment in radeon_vram_location in the drm kernel
code).
So, have you verified that the aperture is not aligned to its size for
you? If it's not, does aligning it help stability with AGP?
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
