Hi, > From: Mark Rutland [mailto:mark.rutland@xxxxxxx] > > On Fri, Oct 04, 2013 at 08:49:43PM +0100, Pekon Gupta wrote: > > OMAP NAND driver currently supports multiple flavours of 1-bit Hamming > > ecc-scheme, like: > > - OMAP_ECC_HAMMING_CODE_DEFAULT > > 1-bit hamming ecc code using software library > > - OMAP_ECC_HAMMING_CODE_HW > > 1-bit hamming ecc-code using GPMC h/w engine > > - OMAP_ECC_HAMMING_CODE_HW_ROMCODE > > 1-bit hamming ecc-code using GPMC h/w engin with ecc-layout > compatible > > to ROM code. > > > > This patch combines above multiple ecc-schemes into single > implementation: > > - OMAP_ECC_HAM1_CODE_HW > > 1-bit hamming ecc-code using GPMC h/w engine with ROM-code > compatible > > ecc-layout. > > If I have my NAND formatted with one of the existing ECC schemes (e.g. > OMAP_ECC_HAMMING_CODE_DEFAULT) will it work with the new > OMAP_ECC_HAM1_CODE_HW scheme? > > Are they all compatible? > Yes, they all are 1-bit hamming code, the only difference between xx_Default and xx_HW was who was doing the ECC calculation. For xx_DEFAULT: ECC calculation was done on CPU via s/w library For xx_HW: ECC calculation was done by in-build h/w engine. So, all HAMMING_xx can be replaced by HAM1_HW. [snip] > > @@ -1342,9 +1342,7 @@ static void __maybe_unused > gpmc_read_timings_dt(struct device_node *np, > > #ifdef CONFIG_MTD_NAND > > > > static const char * const nand_ecc_opts[] = { > > - [OMAP_ECC_HAMMING_CODE_DEFAULT] = "sw", > > - [OMAP_ECC_HAMMING_CODE_HW] = "hw", > > - [OMAP_ECC_HAMMING_CODE_HW_ROMCODE] = "hw- > romcode", > > + [OMAP_ECC_HAM1_CODE_HW] = "ham1", > > [OMAP_ECC_BCH4_CODE_HW] = "bch4", > > [OMAP_ECC_BCH8_CODE_HW] = "bch8", > > Won't this break existing dts which have "sw", "hw", or "hw-romcode"? > > Someone may try to use a new kernel with an old dt, and we marked them > as deprecated, not removed. > HAMMING_xx ECC scheme was used only on legacy platforms, when BCH8 was not available, I have not seen anyone using this scheme *from mainline kernel* from quite a long time. So, it's safe to remove them. This is what was concluded as per below email. http://lists.infradead.org/pipermail/linux-mtd/2013-September/048876.html with regards, pekon -- 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
