mach/io.h cleanup and removal question
Russell King - ARM Linux
linux at arm.linux.org.uk
Fri Jun 8 07:43:16 EDT 2012
On Fri, Jun 08, 2012 at 12:20:40PM +0200, Andrew Lunn wrote:
> Your patchset for mach/io.h cleanup and remove, causes problems on
> mach/io.h for orion5x had a:
> #define IO_SPACE_LIMIT 0xffffffff
> which got removed. This results in a panic at boot:
> * IORESOURCE_IO
> sys->io_offset = 0;
> res.name = "PCIe I/O Space";
> res.flags = IORESOURCE_IO;
> res.start = ORION5X_PCIE_IO_BUS_BASE;
> res.end = res.start + ORION5X_PCIE_IO_SIZE - 1;
> if (request_resource(&ioport_resource, &res))
> panic("Request PCIe IO resource failed\n");
> ORION5X_PCIE_IO_SIZE is 1MB, so the allocation fails because of the
> 64K default.
> arch/arm/include/asm/io.h has the comment:
> * This is the limit of PC card/PCI/ISA IO space, which is by default
> * 64K if we have PC card, PCI or ISA support. Otherwise, default to
> * zero to prevent ISA/PCI drivers claiming IO space (and potentially
> * oopsing.)
> * Only set this larger if you really need inb() et.al. to operate over
> * a larger address space. Note that SOC_COMMON ioremaps each sockets
> * IO space area, and so inb() et.al. must be defined to operate as per
> * readb() et.al. on such platforms.
> Now, i know nothing about how PCI works... So i have a question:
> Which is better, put back parts of io.h so allowing the 1MB
> request_resource, or reduce ORION5X_PCIE_IO_SIZE to 64KB, since from
> the comment it is unlikely an PCI card needs more than 64KB?
Well, the comment about SOC_COMMON doesn't apply as you're not using that.
Probably shrinking ORION5X_PCIE_IO_SIZE to 64K, unless we really have a
requirement to support a larger IO space.
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