[regression, armada-xp] bus: mvebu-mbus: make sure SDRAM CS... breaks PCI

[stsp@list.ru (Stas Sergeev)]

Hello Thomas and arm developers.

I've bisected the patch that makes the PCI devices
(mvsas in my case) to cause the entire system hang.


commit 1737cac6936938a9bc52c03c4a3ff2032c702fa5
Author: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Date:   Fri Jan 9 10:59:04 2015 -0600

    bus: mvebu-mbus: make sure SDRAM CS for DMA don't overlap the MBus bridge wi


That patch looks into mblock for the hole at the end of 4G
space and rounds down the DRAM window size.
The problem is that the window sizes must be the power of 2.
Here's the quote from Marvel datasheet:
---
The size must be programmed as a set of 1s (starting from the LSB) followed by a set of
0s. The set of 1s defines the size. For example, if Size[7:0] is set to 0x0F, it defines a size of 256 MB
(number of 1s is 4, 2^4 x 16 MB = 256 MB).
---
This basically mean that if the size is the power of 2, you
can just subtract 1 and apply the AND mask, but if it is not
the power of 2, you need to round-up. But round-up will again
create an overlap with MBus bridge, defeating the purpose of the
patch.

I think the patch should be reverted.
After reverting it I've got the stable system with mvsas working fine.

If you have any other ideas than to revert patch, I can test.