> + switch (entry->mmap_type) {
> + case HNS_ROCE_MMAP_TYPE_DB:
> + prot = pgprot_noncached(vma->vm_page_prot);
> + break;
> + case HNS_ROCE_MMAP_TYPE_TPTR:
> + prot = vma->vm_page_prot;
> + break;
> + /*
> + * The BAR region of direct WQE supports Early Write Ack,
> + * so pgprot_device is used to improve performance.
> + */
> + case HNS_ROCE_MMAP_TYPE_DWQE:
> + prot = pgprot_device(vma->vm_page_prot);
> + break;
> + default:
> + return -EINVAL;
> + }
i am still not convinced why HNS_ROCE_MMAP_TYPE_DB needs nocache and HNS_ROCE_MMAP_TYPE_DWQE needs
device. generally people use ioremap() to map pci bar spaces in pci device drivers, and ioremap()
is pretty much nGnRE:
#define ioremap(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE))
#define ioremap_np(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRnE))
i am only seeing four places which are using nE in kernel:
# line filename / context / line
1 866 drivers/of/address.c <<of_iomap>>
return ioremap_np(res.start, resource_size(&res));
2 901 drivers/of/address.c <<of_io_request_and_map>>
mem = ioremap_np(res.start, resource_size(&res));
3 89 include/linux/io.h <<pci_remap_cfgspace>>
return ioremap_np(offset, size) ?: ioremap(offset, size);
4 47 lib/devres.c <<__devm_ioremap>>
addr = ioremap_np(offset, size);
so i guess nGnRE is quite safe for pci device bar spaces. for config space, it is a different story
though which is the 3rd one in the above list:
#ifdef CONFIG_PCI
/*
* The PCI specifications (Rev 3.0, 3.2.5 "Transaction Ordering and
* Posting") mandate non-posted configuration transactions. This default
* implementation attempts to use the ioremap_np() API to provide this
* on arches that support it, and falls back to ioremap() on those that
* don't. Overriding this function is deprecated; arches that properly
* support non-posted accesses should implement ioremap_np() instead, which
* this default implementation can then use to return mappings compliant with
* the PCI specification.
*/
#ifndef pci_remap_cfgspace
#define pci_remap_cfgspace pci_remap_cfgspace
static inline void __iomem *pci_remap_cfgspace(phys_addr_t offset,
size_t size)
{
return ioremap_np(offset, size) ?: ioremap(offset, size);
}
#endif
#endif
Thanks
Barry
