Subject: [PATCH] dmaengine: pl330: do not generate unaligned access

From: [email-masked] (Vinod Koul)
Date: Thu, 8 Dec 2016 21:29:35 +0530

On Wed, Dec 07, 2016 at 01:17:40PM +0000, Vladimir Murzin wrote:
> When PL330 is used with !MMU the following fault is seen:
> 
> Unhandled fault: alignment exception (0x801) at 0x8f26a002
> Internal error: : 801 [#1] ARM
> Modules linked in:
> CPU: 0 PID: 640 Comm: dma0chan0-copy0 Not tainted 4.8.0-6a82063-clean+ #1600
> Hardware name: ARM-Versatile Express
> task: 8f1baa80 task.stack: 8e6fe000
> PC is at _setup_req+0x4c/0x350
> LR is at 0x8f2cbc00
> pc : [<801ea538>]    lr : [<8f2cbc00>]    psr: 60000093
> sp : 8e6ffdc0  ip : 00000000  fp : 00000000
> r10: 00000000  r9 : 8f2cba10  r8 : 8f2cbc00
> r7 : 80000013  r6 : 8f21a050  r5 : 8f21a000  r4 : 8f2ac800
> r3 : 8e6ffe18  r2 : 00944251  r1 : ffffffbc  r0 : 8f26a000
> Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment none
> Control: 00c5387c
> Process dma0chan0-copy0 (pid: 640, stack limit = 0x8e6fe210)
> Stack: (0x8e6ffdc0 to 0x8e700000)
> fdc0: 00000001 60000093 00000000 8f2cba10 8f26a000 00000004 8f0ae000 8f2cbc00
> fde0: 8f0ae000 8f2ac800 8f21a000 8f21a050 80000013 8f2cbc00 8f2cba10 00000000
> fe00: 60000093 801ebca0 8e6ffe18 000013ff 40000093 00000000 00944251 8f2ac800
> fe20: a0000013 8f2b1320 00001986 00000000 00000001 000013ff 8f1e4f00 8f2cba10
> fe40: 8e6fff6c 801e9044 00000003 00000000 fef98c80 002faf07 8e6ffe7c 00000000
> fe60: 00000002 00000000 00001986 8f1f158d 8f1e4f00 80568de4 00000002 00000000
> fe80: 00001986 8f1f53ff 40000001 80580500 8f1f158d 8001e00c 00000000 cfdfdfdf
> fea0: fdae2a25 00000001 00000004 8e6fe000 00000008 00000010 00000000 00000005
> fec0: 8f2b1330 8f2b1334 8e6ffe80 8e6ffe8c 00001986 00000000 8f21a014 00000001
> fee0: 8e6ffe60 8e6ffe78 00000002 00000000 000013ff 00000001 80568de4 8f1e8018
> ff00: 0000158d 8055ec30 00000001 803f6b00 00001986 8f2cba10 fdae2a25 00000001
> ff20: 8f1baca8 8e6fff24 8e6fff24 00000000 8e6fff24 ac6f3037 00000000 00000000
> ff40: 00000000 8e6fe000 8f1e4f40 00000000 8f1e4f40 8f1e4f00 801e84ec 00000000
> ff60: 00000000 00000000 00000000 80031714 dfdfdfcf 00000000 dfdfdfcf 8f1e4f00
> ff80: 00000000 8e6fff84 8e6fff84 00000000 8e6fff90 8e6fff90 8e6fffac 8f1e4f40
> ffa0: 80031640 00000000 00000000 8000f548 00000000 00000000 00000000 00000000
> ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> ffe0: 00000000 00000000 00000000 00000000 00000013 00000000 dfdfdfcf cfdfdfdf
> [<801ea538>] (_setup_req) from [<801ebca0>] (pl330_tasklet+0x41c/0x490)
> [<801ebca0>] (pl330_tasklet) from [<801e9044>] (dmatest_func+0xb58/0x149c)
> [<801e9044>] (dmatest_func) from [<80031714>] (kthread+0xd4/0xec)
> [<80031714>] (kthread) from [<8000f548>] (ret_from_fork+0x14/0x2c)
> Code: e3a03001 e3e01043 e5c03001 e59d3048 (e5802002)
> 
> This happens because _emit_{ADDH,MOV,GO) accessing to unaligned data
> while writing to buffer. Fix it with writing to buffer byte by byte.

Applied, now.

Although I didn't really like duplicating code for writing bytes, that could
be made a common fn

Thanks
-- 
~Vinod