Hi Brian, >From: Brian Norris >>On Mon, May 19, 2014 at 01:24:41PM +0530, Pekon Gupta wrote: >> --- a/drivers/mtd/nand/omap2.c >> +++ b/drivers/mtd/nand/omap2.c >> @@ -1201,6 +1219,41 @@ static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info >*mtd, >> *ecc_code++ = ((bch_val1 >> 4) & 0xFF); >> *ecc_code++ = ((bch_val1 & 0xF) << 4); >> break; >> + case OMAP_ECC_BCH16_CODE_HW: >> + val = readl(gpmc_regs->gpmc_bch_result6[i]); > >For all of these 'gpmc_bch_resultX' fields, couldn't you make this into >a 2-D array? So to access BCH result 6 at sector i, it would be: > > val = readl(gpmc_regs->gpmc_bch_result[6][i]; > >This could help you to rewrite some of this stuff as loops, instead of >giant blocks of copy-paste-modify. > Thanks for excepting the series. With this series OMAP NAND driver comes to a stable point supporting NAND boot on all latest platforms. I had earlier experimented with something similar to your suggestions but these clean-ups require update in multiple drivers (GPMC, NAND, ...), and it was becoming messy, so I dropped it. There are some practical challenges to this type of clean-up like; (1) GPMC register addresses here "gpmc_regs" are initialized in GPMC driver So your suggested changes will affect multiple subsystems, hence This type of clean-up is bit deferred from sometime. (2) The register space for gpmc_bch_results is not contiguous. GPMC_BCH_RESULT_0 RW 0x240-0x2B0 GPMC_BCH_RESULT_1 RW 0x244-0x2B4 GPMC_BCH_RESULT_2 RW 0x248-0x2B8 GPMC_BCH_RESULT_3 RW 0x24C-0x2BC [...] GPMC_BCH_RESULT_4 RW 0x300-0x370 GPMC_BCH_RESULT_5 RW 0x304-0x374 GPMC_BCH_RESULT_6 RW 0x308-0x378 This is because older version of GPMC hardware IP (like in OMAP3) supported only till BCH8 ecc-scheme. Later same hardware IP was extended to support BCH16. So newer platforms have extended register-map. So it was felt that instead of having separate for..loops lets continue with replicating all 7 GPMC_BCH_RESULT registers. >> + ecc_code[0] = ((val >> 8) & 0xFF); >> + ecc_code[1] = ((val >> 0) & 0xFF); >> + val = readl(gpmc_regs->gpmc_bch_result5[i]); >> + ecc_code[2] = ((val >> 24) & 0xFF); >> + ecc_code[3] = ((val >> 16) & 0xFF); >> + ecc_code[4] = ((val >> 8) & 0xFF); >> + ecc_code[5] = ((val >> 0) & 0xFF); > >A lot of this code can be rewritten to use the endian swapping macros, I >expect. Something like this looks equivalent: > > *((uint32_t *)&ecc_code[2]) = cpu_to_be32(val); > >You could probably fix the types up to make this look a little nicer. > (3) BCH4 use different alignment than BCH8 and BCH16 as ECC syndrome is not bytewise aligned (it's of 6 1/2 bytes = 13 nibbles). So for BCH4 higher-nibble or reg1 is shifted and ORed with lower-nibble of reg2. There is no byte-to-byte mapping. So generic implementation becomes messy. However, Roger Quadros is planning GPMC driver clean-up, so looping him in-case he can incorporate some of these things while re-factoring GPMC code. with regards, pekon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
