Hi, Mark
On 10/13/2014 7:31 PM, Josh Wu wrote:
Hi, Mark
On 10/13/2014 7:16 PM, Mark Rutland wrote:
On Sat, Oct 11, 2014 at 11:01:50AM +0100, Josh Wu wrote:
From: Josh Wu <Josh.wu@xxxxxxxxx>
If there is no PMECC lookup table stored in ROM, or lookup table
offset is
not specified, PMECC driver should build it in DDR by itself.
That make the PMECC driver work for some board which doesn't has PMECC
lookup table in ROM.
The PMECC use the BCH algorithm, so based on the build_gf_tables()
function in lib/bch.c, we can build the Galois Field lookup table.
For more information can refer to section 5.4 of PMECC controller
application note:
http://www.atmel.com/images/doc11127.pdf
Signed-off-by: Josh Wu <josh.wu@xxxxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
---
v1 -> v2:
make create_lookup_table() static.
v2 -> v3:
rewrite the build_gf_tables() function based on lib/bch.c.
add error handling in create_lookup_table().
.../devicetree/bindings/mtd/atmel-nand.txt | 6 +-
drivers/mtd/nand/atmel_nand.c | 81
++++++++++++++++++++--
drivers/mtd/nand/atmel_nand_ecc.h | 4 ++
3 files changed, 85 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.txt
b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
index 6edc3b6..1fe6dde 100644
--- a/Documentation/devicetree/bindings/mtd/atmel-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
@@ -5,7 +5,9 @@ Required properties:
- reg : should specify localbus address and size used for the chip,
and hardware ECC controller if available.
If the hardware ECC is PMECC, it should contain address and
size for
- PMECC, PMECC Error Location controller and ROM which has lookup
tables.
+ PMECC and PMECC Error Location controller.
+ The PMECC lookup table address and size in ROM is optional. If not
+ specified, driver will build it in runtime.
- atmel,nand-addr-offset : offset for the address latch.
- atmel,nand-cmd-offset : offset for the command latch.
- #address-cells, #size-cells : Must be present if the device has
sub-nodes
@@ -27,7 +29,7 @@ Optional properties:
are: 512, 1024.
- atmel,pmecc-lookup-table-offset : includes two offsets of lookup
table in ROM
for different sector size. First one is for sector size 512, the
next is for
- sector size 1024.
+ sector size 1024. If not specified, driver will build the table
in runtime.
I'm not sure we need to mention this in the binding.
That said, if we can build this dynamically, can't we always do so, and
never need this property?
Since board like at91sam9x5, sama5d3xek has a rom lookup table. And
the sama5d4ek has no rom lookup table.
To present this, I make this property as optional.
But yes, the pmecc lookup table related properties can be removed as
driver can build it in runtime.
The cost is we need to use more memory to store the table.
In precisely, the table need to 32k bytes memory for 512-sector, and 64k
bytes for 1024-sector.
Also I spend time to testing the performance of this version.
Compare with the version which use the SRAM rom lookup table, this
version (build table in runtim) cost about 5~10ms more.
So I prefer to keep this property as optional.
Best Regards,
Josh Wu
Mark.
Best Regards,
Josh Wu
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
