mtd: rawnand: jedec: Adapt the parameter page read to constraint controllers

We already know that there are controllers not able to read the three
copies of the parameter page in one go. The workaround was to first
request the controller to assert command and address cycles on the
NAND bus to trigger a parameter page read, and then do a read
operation for each page.

But there are also controllers which are not able to split the
parameter page read between the command/address cycles and the actual
data operation.

Let's use a regular PARAMETER PAGE READ operation for the first
iteration and use eithe a CHANGE READ COLUMN or a simple DATA READ
operation for the following copies, depending on what the controller
supports. The default for non-exec-op compliant drivers remains
unchanged: use a SIMPLE READ.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200507105241.14299-11-miquel.raynal@bootlin.com

diff --git a/drivers/mtd/nand/raw/nand_jedec.c b/drivers/mtd/nand/raw/nand_jedec.c
index 63069f1948a838d74d902d14dadb14682fb5717f..b15c42f487559d4fa24480938522dc814071d171 100644 (file)
--- a/drivers/mtd/nand/raw/nand_jedec.c
+++ b/drivers/mtd/nand/raw/nand_jedec.c
@@ -27,6 +27,7 @@ int nand_jedec_detect(struct nand_chip *chip)
        struct nand_memory_organization *memorg;
        struct nand_jedec_params *p;
        struct jedec_ecc_info *ecc;
+       bool use_datain = false;
        int jedec_version = 0;
        char id[5];
        int i, val, ret;
@@ -44,14 +45,20 @@ int nand_jedec_detect(struct nand_chip *chip)
        if (!p)
                return -ENOMEM;
 
-       ret = nand_read_param_page_op(chip, 0x40, NULL, 0);
-       if (ret) {
-               ret = 0;
-               goto free_jedec_param_page;
-       }
+       if (!nand_has_exec_op(chip) ||
+           !nand_read_data_op(chip, p, sizeof(*p), true, true))
+               use_datain = true;
 
        for (i = 0; i < JEDEC_PARAM_PAGES; i++) {
-               ret = nand_read_data_op(chip, p, sizeof(*p), true, false);
+               if (!i)
+                       ret = nand_read_param_page_op(chip, 0x40, p,
+                                                     sizeof(*p));
+               else if (use_datain)
+                       ret = nand_read_data_op(chip, p, sizeof(*p), true,
+                                               false);
+               else
+                       ret = nand_change_read_column_op(chip, sizeof(*p) * i,
+                                                        p, sizeof(*p), true);
                if (ret) {
                        ret = 0;
                        goto free_jedec_param_page;