* Ivan Djelic <ivan.djelic@xxxxxxxxxx> [120425 11:33]: > Hi Tony, > Thanks for the review, > > On Wed, Apr 25, 2012 at 06:03:14PM +0100, Tony Lindgren wrote: > (...) > > > #define GPMC_ECC1_RESULT 0x200 > > > +#define GPMC_ECC_BCH_RESULT_0 0x240 > > > > Can you please add a comment here saying something like: > > > > #define GPMC_ECC_BCH_RESULT_0 0x240 /* Not available on omap2 */ > > OK sure. > > > > + /* check if ecc module is in use */ > > > + if (gpmc_ecc_used != -EINVAL) > > > + return -EINVAL; > > > + /* > > > + * FIXME: some OMAP3 revisions have a hardware bug which prevents > > > + * the 4-bit BCH mode from working properly. Such revisions could be > > > + * detected and rejected here. > > > + */ > > > > This should then be disabled to avoid corruption. Maybe only allow it > > initially on omaps that have been tested? And for omap2 it should return > > error for sure. > > OK I'll add a check. > > > > > Or do you know the broken omap3 versions? > > Well, I was hoping that someone from linux-omap could tell me :) > I found this HW ECC feature table in > http://processors.wiki.ti.com/index.php/Raw_NAND_ECC: > > 1b 4b 8b > --------------------------- > OMAP35x YES NO YES > AM35x YES YES YES > AM/DM37x YES YES YES > > and other wiki pages confirmed that 4-bit mode is not supported on all OMAP35xx chips. > OTOH, I know from TI support that 4-bit mode is at least supported on > OMAP3630 ES1.x (x >= 1). > > So, a conservative approach would be to reject 4-bit mode on all chips but > omap3630 with rev >= 1.1. Other revisions/chips could be added later if they are > confirmed to work; what do you think ? Sounds good to me. > > Also, should you first request this feature in case multiple drivers > > need to share it? > > According to TI documentation (OMAP36xx ES1.x TRM, §10.1.4, GPMC functional diagram), > the GPMC ECC engines (Hamming and BCH) are dedicated to NAND access only; therefore > I believe the mtd driver is the only potential user of this feature. > Also, the existing Hamming ecc API does not perform any request; or did I miss > something? If I need to perform the request, is there an existing api to do so? OK I guess the only conflict would be multiple NAND chips then, which we don't have at least currently AFAIK. Tony -- 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
