Can we remove the PCIe IO resource for i.MX6 if not using it?

[GregT]

I don't think we need the io resource for the PCIe on the i.MX6.  We will not be supporting legacy PCI and we have a dedicated embedded system that only communicates with FPGAs through BARs and MSI interrrupts.  Can we remove the io resource allocation in the pcie.c driver and add 1MB to the memory resource as shown below?

So remove this:

/*
* IORESOURCE_IO
*/
snprintf(pp->io_space_name, sizeof(pp->io_space_name),
"PCIe %d I/O", pp->index);
pp->io_space_name[sizeof(pp->io_space_name) - 1] = 0;
pp->res[0].name = pp->io_space_name;
if (pp->index == 0) {
pp->res[0].start = PCIE_ARB_BASE_ADDR + SZ_16M - SZ_2M;
pp->res[0].end = pp->res[0].start + SZ_1M - 1;
}
pp->res[0].flags = IORESOURCE_IO;
if (request_resource(&ioport_resource, &pp->res[0]))
panic("Request PCIe IO resource failed\n");
sys->resource[0] = &pp->res[0];

and change the memory resource to:

/*
* IORESOURCE_MEM
*/
snprintf(pp->mem_space_name, sizeof(pp->mem_space_name),
"PCIe %d MEM", pp->index);
pp->mem_space_name[sizeof(pp->mem_space_name) - 1] = 0;
pp->res[0].name = pp->mem_space_name;
if (pp->index == 0) {
pp->res[0].start = PCIE_ARB_BASE_ADDR;
pp->res[0].end = pp->res[0].start + SZ_16M - SZ_1M - 1;
}
pp->res[0].flags = IORESOURCE_MEM;
if (request_resource(&iomem_resource, &pp->res[0]))
panic("Request PCIe Memory resource failed\n");
sys->resource[0] = &pp->res[0];

Thanks in advance,

Greg

[GregT]

I've made the above changes and our system is still running correctly.  Looks like an easy way to get an extra MB for PCIe BAR space if you don't need to support legacy PCI devices that use I/O resources.

[b36401]

Yes. It can be tuned with BAR configuration.
However officially it is not recommended.

Have a great day,
Victor

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