mtd: nand: add NAND_BUSWIDTH_AUTO to autodetect bus width (64b37b2a) · Commits · 戴 / test

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@parrot.com> Signed-off-by:

Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

drivers/mtd/nand/nand_base.c

+9 −5

Original line number	Diff line number	Diff line
		@@ -3250,11 +3250,15 @@ ident_done:
		break;
		}

		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!
		*/
		if (busw != (chip->options & NAND_BUSWIDTH_16)) {
		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);

include/linux/mtd/nand.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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 */

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