Commit 8429bb39 authored Dec 03, 2013 by Brian Norris

mtd: nand: support Micron READ RETRY



Micron provides READ RETRY support via the ONFI vendor-specific
parameter block (to indicate how many read-retry modes are available)
and the ONFI {GET,SET}_FEATURES commands with a vendor-specific feature
address (to support reading/switching the current read-retry mode).

The recommended sequence is as follows:

  1. Perform PAGE_READ operation
  2. If no ECC error, we are done
  3. Run SET_FEATURES with feature address 89h, mode 1
  4. Retry PAGE_READ operation
  5. If ECC error and there are remaining supported modes, increment the
     mode and return to step 3. Otherwise, this is a true ECC error.
  6. Run SET_FEATURES with feature address 89h, mode 0, to return to the
     default state.

This patch implements the chip->setup_read_retry() callback for
Micron and fills in the chip->read_retries.

Tested on Micron MT29F32G08CBADA, which supports 8 read-retry modes.

The Micron vendor-specific table was checked against the datasheets for
the following Micron NAND:

Needs retry   Cell-type    Part number          Vendor revision    Byte 180
-----------   ---------    ----------------     ---------------    ------------
No            SLC          MT29F16G08ABABA      1                  Reserved (0)
No            MLC          MT29F32G08CBABA      1                  Reserved (0)
No            SLC          MT29F1G08AACWP       1                  0
Yes           MLC          MT29F32G08CBADA      1                  08h
Yes           MLC          MT29F64G08CBABA      2                  08h

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Huang Shijie <b32955@freescale.com>

parent ba84fb59

drivers/mtd/nand/nand_base.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -2979,6 +2979,30 @@ ext_out:
		return ret;
		}

		static int nand_setup_read_retry_micron(struct mtd_info *mtd, int retry_mode)
		{
		struct nand_chip *chip = mtd->priv;
		uint8_t feature[ONFI_SUBFEATURE_PARAM_LEN] = {retry_mode};

		return chip->onfi_set_features(mtd, chip, ONFI_FEATURE_ADDR_READ_RETRY,
		feature);
		}

		/*
		* Configure chip properties from Micron vendor-specific ONFI table
		*/
		static void nand_onfi_detect_micron(struct nand_chip *chip,
		struct nand_onfi_params *p)
		{
		struct nand_onfi_vendor_micron micron = (void )p->vendor;

		if (le16_to_cpu(p->vendor_revision) < 1)
		return;

		chip->read_retries = micron->read_retry_options;
		chip->setup_read_retry = nand_setup_read_retry_micron;
		}

		/*
		* Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
		*/
		@@ -3085,6 +3109,9 @@ static int nand_flash_detect_onfi(struct mtd_info mtd, struct nand_chip chip,
		pr_warn("Could not retrieve ONFI ECC requirements\n");
		}

		if (p->jedec_id == NAND_MFR_MICRON)
		nand_onfi_detect_micron(chip, p);

		return 1;
		}

include/linux/mtd/nand.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -219,6 +219,9 @@ struct nand_chip;
		/* ONFI feature address */
		#define ONFI_FEATURE_ADDR_TIMING_MODE 0x1

		/* Vendor-specific feature address (Micron) */
		#define ONFI_FEATURE_ADDR_READ_RETRY 0x89

		/* ONFI subfeature parameters length */
		#define ONFI_SUBFEATURE_PARAM_LEN 4

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