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authorAndreas Bießmann <andreas.devel@googlemail.com>2013-04-05 04:55:21 +0000
committerTom Rini <trini@ti.com>2013-04-08 11:29:05 -0400
commit4a0930069b596ae27267a0e7cd44199e2270afa5 (patch)
tree06242fd84a0a21e8316b6040ff530ed43a674116 /doc
parentda634ae3567cc2df435f8617dbc95db2d079bf11 (diff)
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omap_gpmc: add support for hw assisted BCH8
The kernel states: ---8<--- The OMAP3 GPMC hardware BCH engine computes remainder polynomials, it does not provide automatic error location and correction: this step is implemented using the BCH library. --->8--- And we do so in u-boot. This implementation uses the same layout for BCH8 but it is fix. The current provided layout does only work with 64 Byte OOB. Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com> Cc: Tom Rini <trini@ti.com> Cc: Ilya Yanok <ilya.yanok@cogentembedded.com> Cc: Scott Wood <scottwood@freescale.com> Cc: Mansoor Ahamed <mansoor.ahamed@ti.com> Cc: Thomas Weber <thomas.weber.linux@googlemail.com>
Diffstat (limited to 'doc')
-rw-r--r--doc/README.omap328
1 files changed, 28 insertions, 0 deletions
diff --git a/doc/README.omap3 b/doc/README.omap3
index 0a37de0..1fbe79d 100644
--- a/doc/README.omap3
+++ b/doc/README.omap3
@@ -145,6 +145,34 @@ int omap3_dma_wait_for_transfer(uint32_t chan)
int omap3_dma_get_revision(uint32_t *minor, uint32_t *major)
Read silicon Revision of the DMA module
+NAND
+====
+
+There are some OMAP3 devices out there with NAND attached. Due to the fact that
+OMAP3 ROM code can only handle 1-bit hamming ECC for accessing first page
+(place where SPL lives) we require this setup for u-boot at least when reading
+the second progam within SPL. A lot of newer NAND chips however require more
+than 1-bit ECC for the pages, some can live with 1-bit for the first page. To
+handle this we can switch to another ECC algorithm after reading the payload
+within SPL.
+
+BCH8
+----
+
+To enable hardware assisted BCH8 (8-bit BCH [Bose, Chaudhuri, Hocquenghem]) on
+OMAP3 devices we can use the BCH library in lib/bch.c. To do so add CONFIG_BCH
+to enable the library and CONFIG_NAND_OMAP_BCH8 to to enable hardware assisted
+syndrom generation to your board config.
+The NAND OOB layout is the same as in linux kernel, if the linux kernel BCH8
+implementation for OMAP3 works for you so the u-boot version should also.
+When you require the SPL to read with BCH8 there are two more configs to
+change:
+
+ * CONFIG_SYS_NAND_ECCPOS (must be the same as .eccpos in
+ GPMC_NAND_HW_BCH8_ECC_LAYOUT defined in
+ arch/arm/include/asm/arch-omap3/omap_gpmc.h)
+ * CONFIG_SYS_NAND_ECCSIZE must be 512
+ * CONFIG_SYS_NAND_ECCBYTES must be 13 for this BCH8 setup
Acknowledgements
================