On Sat, Jan 29, 2011 at 12:45:25PM +0100, Matthieu Herrb wrote:
> Hi,
>
> More last minute X patches...
>
> mpf@ reported in PR6517 a problem with his 965GM chipset.
>
> He did some debugging and found that a patch to the kernel i915 drm
> driver from one of the X.Org maintaines (Chris Wilson) fixes his
> issues. I don't understand the patch (the X.Org bug report is about
> i855 cache coherency problems, not about 965GM) but since it helps
> both mpf and mcbride@ machines, I would like to see this committed.
>
> But wider testing is needed. Please apply the patch below to any
> machine you have running X with an intel chipset. Report success or
> failure to me please, with a dmesg and /var/log/Xorg.0.log.
>
> Thanks in advance.
>
> Original bug report:
> https://bugs.freedesktop.org/show_bug.cgi?id=27187
> and patch :
> https://bugs.freedesktop.org//attachment.cgi?id=41531
>
> Index: i915_drv.c
> ===================================================================
> RCS file: /cvs/OpenBSD/src/sys/dev/pci/drm/i915_drv.c,v
> retrieving revision 1.101
> diff -u -r1.101 i915_drv.c
> --- i915_drv.c 21 Sep 2010 23:05:41 -0000 1.101
> +++ i915_drv.c 29 Jan 2011 08:32:29 -0000
> @@ -995,16 +995,17 @@
> bus_space_write_4(dev_priv->ifp.i9xx.bst,
> dev_priv->ifp.i9xx.bsh, 0, 1);
> } else {
> - /*
> - * I8XX don't have a flush page mechanism, but do have the
> - * cache. Do it the bruteforce way. we write 1024 byes into
> - * the cache, then clflush them out so they'll kick the stuff
> - * we care about out of the chipset cache.
> - */
> - if (dev_priv->ifp.i8xx.kva != NULL) {
> - memset(dev_priv->ifp.i8xx.kva, 0, 1024);
> - agp_flush_cache_range((vaddr_t)dev_priv->ifp.i8xx.kva,
> - 1024);
> + int i;
> +
> + wbinvd();
That is a very large hammer. How often is this code called?
> +
> +#define I830_HIC 0x70
> +
> + I915_WRITE(I830_HIC, (I915_READ(I830_HIC) | (1<<31)));
> + for (i = 1000; i; i--) {
^^^^^^^^^^^^^^^^^^^^^^
really?
> + if (!(I915_READ(I830_HIC) & (1<<31)))
> + break;
> + delay(100);
> }
> }
> }
>
> --
> Matthieu Herrb
