2013/2/6 Grant Likely <grant.lik...@secretlab.ca>: > On Tue, Feb 5, 2013 at 3:12 PM, Arnd Bergmann <a...@arndb.de> wrote: >> On Tuesday 05 February 2013 18:03:31 Alexey Brodkin wrote: >>> The Xilinx System ACE Compact Flash chip is a true little-endian device >>> and the PLB is a big-endian bus. Therefore the XPS System ACE Interface >>> Controller will do a bit-swap in each byte when connecting the PLB data >>> bus to the System ACE data bus as shown in Table 2. >>> >>> Note however, that the XPS System ACE Interface Controller does not >>> perform the byte swapping necessary to interface to a little-endian >>> device when configured to use 16-bit mode. Therefore, the software >>> drivers provided for this core will perform the necessary byte-swapping >>> to correctly interface to the Xilinx System ACE Compact Flash chip as >>> shown in Table 3. >> >> Ok. In this case, I would recommend making the default for this driver >> little-endian, and adding a quirk for broken hardware bridges like the >> one you cited to have a mixed-endian mode if configured so at compile >> time. >> >> It seems that on all normal platforms, this device should behave as >> little-endian, while the Xilinx bridge can be either big-endian >> or little-endian, depending on whether it is used in 8-bit or 16-bit >> mode, so if we are using this, it cannot be known at compile time. > > The driver already handles this. It has three sets of accessors; > 8-bit, 16-bit LE and 16-bit BE *and* when doing 16-bit it figures out > on its own which set to use at runtime. There is nothing controversial > here. The only problem is that the driver is currently using in_/out_ > IO accessors instead of ioread/iowrite variants.
I have looked at the patches from more practical side and I have tested it on microblaze big endian in 16bit mode and I have found that sysace driver stop to work. After that I have looked at ioread/iowrite microblaze implementation and implementation of that functions is wrong. I have fixed it but looking at using asm-generic/io.h for microblaze. I will do more tests and let you know. 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
