Re: [Linux-ia64] framebuffer console

Richard Hirst
2001-11-04T22:06:37Z

On Wed, Oct 24, 2001 at 04:21:08PM -0700, David Mosberger wrote:
> >>>>> On Wed, 24 Oct 2001 12:26:59 +0100, Richard Hirst <rhirst@linuxcare.com> said:
>
> Richard> This patch solves the problem. Still surprised that cached
> Richard> accesses to the video memory crash the machine though..
>
> My understanding is that Merced doesn't handle cache line sized
> transactions to the PCI bus. Instead of going uncached, you might be
> able to use write-combining (for the video framebuffer, not for memory
> mapped control registers). That can give you noticably better
> performance.

Yes, write combining works. Could you include this in your tree
please, (patch is from a 2.4.9 tree)

Thanks,
Richard

--- linux/drivers/video/fbmem.c.ori Mon Nov 5 01:53:01 2001
+++ linux/drivers/video/fbmem.c Mon Nov 5 01:53:05 2001
@@ -605,6 +605,8 @@
vma->vm_flags |= VM_IO;
#elif defined(__sh__)
pgprot_val(vma->vm_page_prot) &= ~_PAGE_CACHABLE;
+#elif defined(__ia64__)
+ vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
#else
#warning What do we have to do here??
#endif