RE: [PATCH 0/1] Fix OMAP2 NAND ONFI device detection

["Gupta, Pekon" <pekon@ti.com>]

> From: Ezequiel Garcia
[...]

> But: on the other hand, I'd really like you to convince me as to
> why is it so bad to require the DTB to have the proper GPMC bus width.
> 
No its not at all bad, all I want is either of the one way (not mixture of both).
- Either depend on DT completely (which is current case for all drivers)
- OR depend on ONFI and nand_flash_id[] for bus-width detection.


> Once again:
> 1. the NAND devices aren't hot-pluggable
> 2. the "user" (who is actually an engineer, not some regular dummy user)
> knows perfectly well the width of the device.
> 
> What's the problem with describing the hardware in the DT and saving us
> lots of runtime re-configuration trouble?

I agree with both your arguments above.
So shouldn't we kill NAND_BUSWIDTH_AUTO ?
And probably therefore  NAND_BUSWIDTH_AUTO isn't that popular.

Now what remains is ONFI probe, which should always happen in x8 mode.
So for that below patch should be sufficient ..

----------------------
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index ec1db1e..d1220fb 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2942,14 +2942,8 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
                chip->read_byte(mtd) != 'F' || chip->read_byte(mtd) != 'I')
                return 0;

-       /*
-        * ONFI must be probed in 8-bit mode or with NAND_BUSWIDTH_AUTO, not
-        * with NAND_BUSWIDTH_16
-        */
-       if (chip->options & NAND_BUSWIDTH_16) {
-               pr_err("ONFI cannot be probed in 16-bit mode; aborting\n");
-               return 0;
-       }
+       /* ONFI must be probed in 8-bit mode only */
+       nand_set_defaults(chip, 0);

        chip->cmdfunc(mtd, NAND_CMD_PARAM, 0, -1);
        for (i = 0; i < 3; i++) {
@@ -2962,7 +2956,7 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,

        if (i == 3) {
                pr_err("Could not find valid ONFI parameter page; aborting\n");
-               return 0;
+               goto return_error;
        }

        /* Check version */
@@ -2980,7 +2974,7 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,

        if (!chip->onfi_version) {
                pr_info("%s: unsupported ONFI version: %d\n", __func__, val);
-               return 0;
+               goto return_error;
        }

        sanitize_string(p->manufacturer, sizeof(p->manufacturer));
@@ -3033,6 +3027,12 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
        }

        return 1;
+
+return_error:
+       /* revert original bus-width */
+       nand_set_defaults( chip->options & NAND_BUSWIDTH_16);
+       return 0;
+
 }

 /*
------------------------- 


with regards, pekon