GPMI-NAND: Wrong ECC size in driver

[Marek Vasut]

Hi,

the gpmi-nand.c driver apparently has misconfigured ecc.size field:

drivers/mtd/nand/gpmi-nand/gpmi-nand.c:
---------- >8 ----------
1493         chip->ecc.mode          = NAND_ECC_HW;
1494         chip->ecc.size          = 1;
1495         chip->ecc.layout        = &gpmi_hw_ecclayout;
---------- 8< ----------

This boils down to misconfigured mtd->subpage_sft in:

drivers/mtd/nand/nand_base.c:
---------- >8 ----------
3434         /* Allow subpage writes up to ecc.steps. Not possible for MLC flash 
*/
3435         if (!(chip->options & NAND_NO_SUBPAGE_WRITE) &&
3436             !(chip->cellinfo & NAND_CI_CELLTYPE_MSK)) {
3437                 switch (chip->ecc.steps) {
3438                 case 2:
3439                         mtd->subpage_sft = 1;
3440                         break;
3441                 case 4:
3442                 case 8:
3443                 case 16:
3444                         mtd->subpage_sft = 2;
3445                         break;
3446                 }
3447         }
3448         chip->subpagesize = mtd->writesize >> mtd->subpage_sft;
---------- 8< ----------

The mtd->subpage_sft is accidentally 0 by default. Therefore, the subpage size 
is mtd->writesize >> 0. Therefore the subpage size reported to UBI formating 
tools is the size of whole page, which works. Now, if I correct the problem by 
setting ecc.size properly to 512 bytes, I get into trouble with UBI:

1) UBI formating tools are reported the driver CAN DO subpage writes
2) UBI formating tools are reported the subpage size is 512 bytes

and this happens even though the NAND_NO_SUBPAGE_WRITE option is set by the 
driver. This is because:

drivers/mtd/nand/nand_base.c:
---------- >8 ----------
3072         /* Get chip options, preserve non chip based options */
3073         chip->options &= ~NAND_CHIPOPTIONS_MSK;
3074         chip->options |= type->options & NAND_CHIPOPTIONS_MSK;
---------- 8< ----------

which effectively masks that bit away. So, how are we going to fix it?

Cheers!

Marek