Messages in this thread | | | Date | Mon, 20 Jun 2011 11:45:39 +0200 (CEST) | From | Armin Schindler <> | Subject | Map PCI resource to user space problem. |
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Hello,
when I try to map PCI resource of size < PAGE_SIZE to user space with e.g. remap_pfn_range() the mapping seems to be created, but the access to the PCI device just doesn't work (read returns 0xff).
The same happens when using sysfs. The device has # ls -al /sys/bus/pci/devices/0000\:02\:09.0/resource* -rw------- 1 root root 512 Jun 20 11:33 /sys/bus/pci/devices/0000:02:09.0/resource0 -rw------- 1 root root 256 Jun 20 11:33 /sys/bus/pci/devices/0000:02:09.0/resource1 -rw------- 1 root root 8388608 Jun 20 11:33 /sys/bus/pci/devices/0000:02:09.0/resource2 -rw------- 1 root root 262144 Jun 20 11:33 /sys/bus/pci/devices/0000:02:09.0/resource3
and when I mmap() resource0, a valid address is returned, but reading the area always returns 0xff.
Since a kernel driver can access resource0 here without problems when using ioremap(), I'm not sure what is wrong with the sysfs entry for user space (or using remap_pfn_range() in own mmap function). The only hint I have so far is the size, which is smaller than PAGE_SIZE.
What would be the correct way to map this area to user space?
Thanks, Armin
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