| From | Andy Shevchenko <> | Date | Fri, 5 Mar 2021 17:13:36 +0200 | Subject | Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted |
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On Thu, Mar 4, 2021 at 11:40 PM Hector Martin <marcan@marcan.st> wrote: > > This implements the 'nonposted-mmio' and 'posted-mmio' boolean > properties. Placing these properties in a bus marks all child devices as > requiring non-posted or posted MMIO mappings. If no such properties are > found, the default is posted MMIO. > > of_mmio_is_nonposted() performs the tree walking to determine if a given > device has requested non-posted MMIO. > > of_address_to_resource() uses this to set the IORESOURCE_MEM_NONPOSTED > flag on resources that require non-posted MMIO. > > of_iomap() and of_io_request_and_map() then use this flag to pick the > correct ioremap() variant. > > This mechanism is currently restricted to Apple ARM platforms, as an > optimization.
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> @@ -896,7 +899,10 @@ void __iomem *of_iomap(struct device_node *np, int index) > if (of_address_to_resource(np, index, &res)) > return NULL; > > - return ioremap(res.start, resource_size(&res)); > + if (res.flags & IORESOURCE_MEM_NONPOSTED) > + return ioremap_np(res.start, resource_size(&res)); > + else > + return ioremap(res.start, resource_size(&res));
This doesn't sound right. Why _np is so exceptional? Why don't we have other flavours (it also rings a bell to my previous comment that the flag in ioresource is not in the right place)?
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> + if (res.flags & IORESOURCE_MEM_NONPOSTED) > + mem = ioremap_np(res.start, resource_size(&res)); > + else > + mem = ioremap(res.start, resource_size(&res)); > +
Ditto.
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> + while (node) { > + if (!of_property_read_bool(node, "ranges")) { > + break; > + } else if (of_property_read_bool(node, "nonposted-mmio")) { > + of_node_put(node); > + return true; > + } else if (of_property_read_bool(node, "posted-mmio")) { > + break; > + } > + parent = of_get_parent(node); > + of_node_put(node); > + node = parent; > + }
I believe above can be slightly optimized. Don't we have helpers to traverse to all parents?
-- With Best Regards, Andy Shevchenko
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