[PATCH v2 08/11] mtd: rawnand: jedec: Adapt the parameter page read to constraint controllers

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

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.

All controllers are expected to be able to change the read column
though. So let's use a regular parameter page read operation for the
first iteration and use a change read column operation for the
following copies.

The extra command and address cycles sent over the NAND bus are
negligible compared to the amount of data that is being transferred
anyway.

Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
 drivers/mtd/nand/raw/nand_jedec.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_jedec.c b/drivers/mtd/nand/raw/nand_jedec.c
index 15937e02c64f..b2be9056759a 100644
--- a/drivers/mtd/nand/raw/nand_jedec.c
+++ b/drivers/mtd/nand/raw/nand_jedec.c
@@ -25,7 +25,7 @@ int nand_jedec_detect(struct nand_chip *chip)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
 	struct nand_memory_organization *memorg;
-	struct nand_jedec_params *p;
+	struct nand_jedec_params *p = NULL, *pbuf;
 	struct jedec_ecc_info *ecc;
 	int jedec_version = 0;
 	char id[5];
@@ -40,25 +40,25 @@ int nand_jedec_detect(struct nand_chip *chip)
 		return 0;
 
 	/* JEDEC chip: allocate a buffer to hold its parameter page */
-	p = kzalloc(sizeof(*p), GFP_KERNEL);
-	if (!p)
+	pbuf = kzalloc(sizeof(*pbuf) * JEDEC_PARAM_PAGES, GFP_KERNEL);
+	if (!pbuf)
 		return -ENOMEM;
 
-	ret = nand_read_param_page_op(chip, 0x40, NULL, 0);
-	if (ret) {
-		ret = 0;
-		goto free_jedec_param_page;
-	}
-
 	for (i = 0; i < JEDEC_PARAM_PAGES; i++) {
-		ret = nand_read_data_op(chip, p, sizeof(*p), true);
+		if (!i)
+			ret = nand_read_param_page_op(chip, 0x40, &pbuf[i],
+						      sizeof(*pbuf));
+		else
+			ret = nand_change_read_column_op(chip, sizeof(*pbuf) * i,
+							 &pbuf[i], sizeof(*pbuf),
+							 true);
 		if (ret) {
 			ret = 0;
 			goto free_jedec_param_page;
 		}
 
-		crc = onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 510);
-		if (crc == le16_to_cpu(p->crc))
+		crc = onfi_crc16(ONFI_CRC_BASE, (u8 *)&pbuf[i], 510);
+		if (crc == le16_to_cpu(pbuf[i].crc))
 			break;
 	}
 
@@ -67,6 +67,8 @@ int nand_jedec_detect(struct nand_chip *chip)
 		goto free_jedec_param_page;
 	}
 
+	p = pbuf;
+
 	/* Check version */
 	val = le16_to_cpu(p->revision);
 	if (val & (1 << 2))
@@ -122,6 +124,6 @@ int nand_jedec_detect(struct nand_chip *chip)
 	ret = 1;
 
 free_jedec_param_page:
-	kfree(p);
+	kfree(pbuf);
 	return ret;
 }
-- 
2.20.1


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