Re: [PATCH v12 0/2] MTD: at91: Add PMECC support for at91 nand flash driver

Josh Wu <josh.wu@xxxxxxxxx> · Fri, 29 Jun 2012 17:00:27 +0800

Hi, Artem

On 6/28/2012 11:40 PM, Artem Bityutskiy wrote:

On Thu, 2012-06-28 at 16:21 +0800, Josh Wu wrote:

Those patches is based on the l2-mtd.git three.

Since there are two patches of v11 already pushed, so this version v12 only includes the left two patches.
which includes the modification according to Richard Genoud's review suggestion.

Changes since v11,
	add documentation for atmel nand reg parameter and one example for PMECC support.
	fix the bug: no error reported when fail to get resoures of PMECC ERRLOC or ROM.
	fix the bug: no correction when ecc data has bit flipped.
	add clearer debug information for data correction.

Josh Wu (2):
   MTD: at91: add dt parameters for Atmel PMECC
   MTD: at91: atmel_nand: Update driver to support Programmable Multibit
     ECC controller

  .../devicetree/bindings/mtd/atmel-nand.txt         |   40 +-
  drivers/mtd/nand/atmel_nand.c                      |  801 +++++++++++++++++++-
  drivers/mtd/nand/atmel_nand_ecc.h                  |  114 ++-
  3 files changed, 951 insertions(+), 4 deletions(-)

Aiaiai is not 100% happy, could you take a look?

dedekind@blue:~/git/maintaining$ ../aiaiai/aiaiai-concat-mboxes ~/tmp/wu* | ./verify ../l2-mtd/ atmel_nand
Tested the patch(es) on top of the following commits:
9328bb5 Quick fixes - applied by aiaiai
ea3b6ef mtd: fix bogus inequation
0960e57 mtd: move mtd_read_oob() definition out of mtd.h
0560176 mtd: nand_bbt: refactor check_pattern_no_oob()

--------------------------------------------------------------------------------

Successfully built configuration "arm-at91cap9_defconfig,arm,arm-unknown-linux-gnueabi-", results:

--- before_patching.log
+++ after_patching.log
@@ @@
+drivers/mtd/nand/atmel_nand.c: In function 'pmecc_correct_data':
+drivers/mtd/nand/atmel_nand.c:680:38: warning: variable 'ecc_size' set but not used [-Wunused-but-set-variable]


oops, I'll fix this warning in next version.


+drivers/mtd/nand/atmel_nand.c:480:32: error: bad constant expression [sparse]
+drivers/mtd/nand/atmel_nand.c:488:35: error: bad constant expression [sparse]
+drivers/mtd/nand/atmel_nand.c:633:32: error: bad constant expression [sparse]
+drivers/mtd/nand/atmel_nand.c:635:35: error: bad constant expression [sparse]



I use CodeSourcery 2010q1, and no any error reported. So it seems 

related with the compiler.



From the log, I think the error is caused by the dynamic 2d array: 

smu[cap + 2][2 * cap + 1]. which is used to calculate the sigma table.



Since the smu is allocated when driver is probed, and the length of the 

smu depend on PMECC correction capablity. So when I declare the type of 

smu by following line: (cap is declared as const type)

         int16_t (*smu)[2 * cap + 1];

That make Sparse compiler not happy, since the cap is a variable. so it 

reports an error. But for this case, the CodeSourcery works fine.



For fixing this compile error, in next version,  I will use 1D array 

instead of 2D array, for instance: all smu[i][j] changes to smu[i * num 

+ j].  // in this line, num equal to 2 * cap + 1.

I think in such way, all compiler should be happy. :)


When I send out the next version of the patch, Could you please test it 

about above fix? since I don't have Sparse compiler in my hand. Thanks.




--------------------------------------------------------------------------------




Best Regards,
Josh Wu

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