diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2016-02-17 16:51:40 +0100 |
|---|---|---|
| committer | Felipe Balbi <balbi@kernel.org> | 2016-03-04 15:14:31 +0200 |
| commit | a9458a3b33ea1a00fc9d1beb3c0bb1c2d18855c9 (patch) | |
| tree | 8ceb089342384a43b05c384874c857dbaa803389 /drivers/usb/gadget/udc/pxa25x_udc.c | |
| parent | 62a6abdd427b5fc4d8aad5dac874904e96273e6d (diff) | |
usb: gadget: pxa25x_udc: document endianess better
When I wrote the cleanup patch series, it was not clear how
exactly big-endian mode works on ixp4xx, and whether the driver
was doing this correctly. After discussing with Krzysztof Hałasa,
this has been clarified, so I can update the comment let pxa25x
big-endian (which we don't support) work the same way as ixp4xx.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Diffstat (limited to 'drivers/usb/gadget/udc/pxa25x_udc.c')
| -rw-r--r-- | drivers/usb/gadget/udc/pxa25x_udc.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/usb/gadget/udc/pxa25x_udc.c b/drivers/usb/gadget/udc/pxa25x_udc.c index 6d3acbf3b311..a238da906115 100644 --- a/drivers/usb/gadget/udc/pxa25x_udc.c +++ b/drivers/usb/gadget/udc/pxa25x_udc.c @@ -289,14 +289,14 @@ static void pullup_on(void) mach->udc_command(PXA2XX_UDC_CMD_CONNECT); } -#if defined(CONFIG_ARCH_IXP4XX) && defined(CONFIG_CPU_BIG_ENDIAN) +#if defined(CONFIG_CPU_BIG_ENDIAN) /* - * not sure if this is the correct behavior on ixp4xx in both - * bit-endian and little-endian modes, but it's what the driver - * has always done using direct pointer dereferences: - * We assume that there is a byteswap done in hardware at the - * MMIO register that matches what the CPU setting is, so we - * never swap in software. + * IXP4xx has its buses wired up in a way that relies on never doing any + * byte swaps, independent of whether it runs in big-endian or little-endian + * mode, as explained by Krzysztof Hałasa. + * + * We only support pxa25x in little-endian mode, but it is very likely + * that it works the same way. */ static inline void udc_set_reg(struct pxa25x_udc *dev, u32 reg, u32 val) { |