On Wed, Mar 24, 2021 at 7:12 PM Will Deacon [off-list ref] wrote:

quoted

+/*
+ * ioremap_np needs an explicit architecture implementation, as it
+ * requests stronger semantics than regular ioremap(). Portable drivers
+ * should instead use one of the higher-level abstractions, like
+ * devm_ioremap_resource(), to choose the correct variant for any given
+ * device and bus. Portable drivers with a good reason to want non-posted
+ * write semantics should always provide an ioremap() fallback in case
+ * ioremap_np() is not available.
+ */
+#ifndef ioremap_np
+#define ioremap_np ioremap_np
+static inline void __iomem *ioremap_np(phys_addr_t offset, size_t size)
+{
+     return NULL;
+}
+#endif

Can we implement the generic pci_remap_cfgspace() in terms of ioremap_np()
if it is supported by the architecture? That way, we could avoid defining
both on arm64.

Good idea. It needs a fallback in case the ioremap_np() fails on most
architectures, but that sounds easy enough.

Since pci_remap_cfgspace() only has custom implementations, it sounds like
we can actually make the generic implementation unconditional in the end,
but that requires adding ioremap_np() on 32-bit as well, and I would keep
that separate from this series.

        Arnd