On Sun, 2014-08-03 at 05:32 +0300, Siarhei Siamashka wrote:
If the dram->ppwrsctl (SDR_DPCR) register has the lowest bit set to 1, this means that DRAM is currently in self-refresh mode and retaining the old data. Since we have no idea what to do in this situation yet, just set this register to 0 and initialize DRAM in the same way as on any normal reboot (discarding whatever was stored there).
This part of code was apparently used by the Allwinner boot0 bootloader to handle resume from the so-called super-standby mode. But this particular code got somehow mangled on the way from the boot0 bootloader to the u-boot-sunxi bootloader and has no chance of doing anything even remotely sane. For example:
- in the original boot0 code we had "mctl_write_w(SDR_DPCR, 0x16510000)" (write to the register) and in the u-boot it now looks like "setbits_le32(&dram->ppwrsctl, 0x16510000)" (set bits in the register)
- in the original boot0 code it was issuing three commands "0x12, 0x17, 0x13" (Self-Refresh entry, Self-Refresh exit, Refresh), but in the u-boot they have become "0x12, 0x12, 0x13" (Self-Refresh entry, Self-Refresh entry, Refresh)
Signed-off-by: Siarhei Siamashka siarhei.siamashka@gmail.com
Acked-by: Ian Campbell ijc@hellion.org.uk