On Thu, Oct 1, 2015 at 5:50 PM, Wolfgang Denk <[email protected]> wrote: > On ARM (a LE architecture), clrsetbits_le16() maps down into: > > clrsetbits_le16 -> > out_le16 / in_le16 -> > out_arch, w,le16 / in_arch, w,le16 -> > __raw_writew(cpu_to_le16()) / le16__to_cpu(__raw_readw()) -> > __raw_writew() / __raw_readw() > > while > > writew() -> > __raw_writew(cpu_to_le16(v),__mem_pci(c)) > __raw_writew() > > Both map into __raw_writew() [which then boild down into > __arch_putw() which is just a volatile unsigned short write access. > > So both clrsetbits_le16() and writew() are little endian accessors. > In which way would one write other data to the device than the other?
Yes, you are right. The issue seems to be related to the effect of writing doing 'writew(WCR_WDE, &wdog->wcr)', which writes 0x40 to the register WCR versus 'clrsetbits_le16(&wdog->wcr, 0, WCR_WDE)' which only enables the WDE bit. The kernel driver also does the full write to the WCR register(like we used to have prior to 623d96e89aca6) https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/drivers/watchdog/imx2_wdt.c?id=refs/tags/v4.2.2#n86 This has also the effect of clearing the SRS bit. By the way we need to implement erratum ERR004346 (WDOG: WDOG SRS bit requires to be written twice) in U-boot, but this is an unrelated issue. So the revert seems to be appropriate. The commit log should be adjusted though. Regards, Fabio Estevam _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
