The driver call nand_scan_ident in 8 bit mode, then
readid or onfi detection are done (and detect bus width).
The driver should update its bus width before calling nand_scan_tail.
This work because readid and onfi are read work 8 byte mode.
Note that nand_scan_ident send command (NAND_CMD_RESET, NAND_CMD_READID, NAND_CMD_PARAM), address and read data
The ONFI specificication is not very clear for x16 device if high byte of address should be driven to 0,
but according to [1] it should be ok to not drive it during autodetection.
[1]
3.3.2. Target Initialization
[...]
The Read ID and Read Parameter Page commands only use the lower 8-bits of the data bus.
The host shall not issue commands that use a word data width on x16 devices until the host
determines the device supports a 16-bit data bus width in the parameter page.
Signed-off-by: Matthieu CASTET <matthieu.castet@xxxxxxxxxx>
---
drivers/mtd/nand/nand_base.c | 14 +++++++++-----
include/linux/mtd/nand.h | 7 +++++++
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index abeb8e9..c90ef66 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3245,11 +3245,15 @@ ident_done:
break;
}
- /*
- * Check, if buswidth is correct. Hardware drivers should set
- * chip correct!
- */
- if (busw != (chip->options & NAND_BUSWIDTH_16)) {
+ if (chip->options & NAND_BUSWIDTH_AUTO) {
+ WARN_ON(chip->options & NAND_BUSWIDTH_16);
+ chip->options |= busw;
+ nand_set_defaults(chip, busw);
+ } else if (busw != (chip->options & NAND_BUSWIDTH_16)) {
+ /*
+ * Check, if buswidth is correct. Hardware drivers should set
+ * chip correct!
+ */
pr_info("NAND device: Manufacturer ID:"
" 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id,
*dev_id, nand_manuf_ids[maf_idx].name, mtd->name);
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 24e9159..c8518d4 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -219,6 +219,13 @@ typedef enum {
#define NAND_OWN_BUFFERS 0x00020000
/* Chip may not exist, so silence any errors in scan */
#define NAND_SCAN_SILENT_NODEV 0x00040000
+/*
+ * Autodetect nand buswidth with readid/onfi.
+ * This suppose the driver will configure the hardware in 8 bits mode
+ * when calling nand_scan_ident, and update its configuration
+ * before calling nand_scan_tail.
+ */
+#define NAND_BUSWIDTH_AUTO 0x00080000
/* Options set by nand scan */
/* Nand scan has allocated controller struct */
--
1.7.10.4
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