Re: [PATCH v4 04/47] soc: fsl: qe: introduce qe_io{read,write}* wrappers
From: Timur Tabi <timur@kernel.org>
Date: 2019-11-14 05:08:32
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On 11/12/19 1:14 AM, Rasmus Villemoes wrote:
but that's because readl and writel by definition work on little-endian registers. I.e., on a BE platform, the readl and writel implementation must themselves contain a swab, so the above would end up doing two swabs on a BE platform.
Do you know whether the compiler optimizes-out the double swab?
(On PPC, there's a separate definition of mmio_read32be, namely writel_be, which in turn does a out_be32, so on PPC that doesn't actually end up doing two swabs). So ioread32be etc. have well-defined semantics: access a big-endian register and return the result in native endianness.
It seems weird that there aren't any cross-arch lightweight endian-specific I/O accessors. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel