[U-Boot] [PATCH v2 09/16] mtd/nand/tegra: alignment workaround

[Scott Wood]

On Tue, 2015-07-21 at 00:35 +0200, Marcel Ziswiler wrote:
> From: Marcel Ziswiler <marcel.ziswiler at toradex.com>
> 
> Integrate cache alignment bounce buffer to workaround issues as follows:
> 
> Loading file '/boot/zImage' to addr 0x01000000 with size 4499152 
> (0x0044a6d0)...
> ERROR: v7_dcache_inval_range - start address is not aligned - 0x1f7f0108
> ERROR: v7_dcache_inval_range - stop address is not aligned - 0x1f7f1108
> Done
> Kernel image @ 0x1000000 [ 0x000000 - 0x44a6d0 ]
> 
> Starting kernel ...
> 
> undefined instruction
> pc : [<005ff03c>]          lr : [<0000800c>]
> sp : 0144b6e8  ip : 01000188     fp : 0144a6c8
> r10: 00000000  r9 : 411fc090     r8 : 00000100
> r7 : 00000cfb  r6 : 0144a6d0     r5 : 00000000  r4 : 00008000
> r3 : 0000000c  r2 : 00000100     r1 : 00000cfb  r0 : 00000000
> Flags: nZCv  IRQs off  FIQs off  Mode SVC_32
> Resetting CPU ...
> 
> Signed-off-by: Marcel Ziswiler <marcel.ziswiler at toradex.com>
> ---
> Changes in v2:
> Migrated to using generic bounce buffer implementation as suggested by 
> Simon.

I didn't see Simon's suggestion, but what is the general policy in U-Boot 
supposed to be for I/O alignment?  Responsibility of the API user, or of the 
driver?  Are there other drivers with the same problem?

> -     writel(virt_to_phys(buf), &info->reg->data_block_ptr);
> +     writel((u32)bbstate.bounce_buffer, &info->reg->data_block_ptr);

Why are you converting usage of virt_to_phys() into a u32 cast?

-Scott