Messages in this thread | | | Date | Tue, 5 Feb 2013 13:38:58 +0100 | Subject | Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)_le16 with generic iowrite(read)8/16(be) | From | Michal Simek <> |
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2013/2/5 Benjamin Herrenschmidt <benh@kernel.crashing.org>: > On Tue, 2013-02-05 at 11:54 +0100, Michal Simek wrote: >> >> xilinx ppc is big endian >> xilinx arm is little endian >> xilinx microblaze is little endian and big endian > > You are talking about the core, why should the xsysace block driver be > synthesized with the same endianness as the core ? That's not terribly > useful, especially since reverse load/stores on ppc are essentially > free...
It is done by hardware guys and I can do nothing with it.
>> It is just sharing the same IP across all platforms. Which is better >> than create new devices and new device drivers for it. It means that >> all of them are register compatible but require access with native >> platform endianness as I listed above. > > Every attempt at doing "native platform endianness" has always been a > misguided attempt turning into a trainwreck (see OHCI USB). > > Just pick one endian for the device and stick to it.
It is reality and I can't change it. Arnd mentioned it earlier that USB
>> It is not a problem to create runtime wrapper and even detect endian >> directly in the driver >> but the point if this is the proper design. >> Also ioread32 and ioread32be shouldn't be used on ARM because there >> are missing memory barriers. > > Then fix them, they shouldn't be, it's a bug, it will break many other > drivers. They should be fully equivalent to readl.
I want to be sure about this. I have parsed this again with closer look and seems to me that ioread32 is equal to readl and iowrite32 to writel. Arnd: Am I right?
Thanks, Michal
-- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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