On 4/21/05, Clem Taylor <clem.taylor@xxxxxxxxx> wrote:
> I'm working on a Au1550 driver for a PCI based co-processor. The
> driver provides mmap() that allows the mapping of a PCI BAR. From
> userspace I can happily read from the mmaped region, but writes just
> hang the user space program. gdb shows that the user program is
> sitting at the write statement. The read() and write() system calls
> work just fine as well.
I saw in drivers/video/epson1356fb.c it was doing:
// FIXME: shouldn't have to do this. If the pages are marked writeable,
// the TLB fault handlers should set these.
pgprot_val(vma->vm_page_prot) |= (_PAGE_DIRTY | _PAGE_VALID);
So I tried adding this before my io_remap_page_range() and it seems to
have fixed my problem. My mmap() write to a PCI device is working now.
I tried setting just the _PAGE_DIRTY bit and that seems to be the
trick. Any ideas why I would need do to this or what is going on?
--Clem
