Commit f486287d authored by Masahiro Yamada's avatar Masahiro Yamada Committed by Boris Brezillon
Browse files

mtd: nand: denali: fix bank reset function to detect the number of chips 



The nand_scan_ident() iterates over maxchips, and calls nand_reset()
for each.  This driver currently passes the maximum number of banks
(=chip selects) supported by the controller as maxchips.  So, maxchips
is typically 4 or 8.  Usually, less number of NAND chips are connected
to the controller.

This can be a problem for ONFi devices.  Now, this driver implements
->setup_data_interface() hook, so nand_setup_data_interface() issues
Set Features (0xEF) command, which waits until the chip returns R/B#
response.  If no chip there, we know it never happens, but the driver
still ends up with waiting for a long time.  It will finally bail-out
with timeout error and the driver will work with existing chips, but
unnecessary wait will give a bad user experience.

The denali_nand_reset() polls the INTR__RST_COMP and INTR__TIME_OUT
bits, but they are always set even if not NAND chip is connected to
that bank.  To know the chip existence, INTR__INT_ACT bit must be
checked; this flag is set only when R/B# is toggled.  Since the Reset
(0xFF) command toggles the R/B# pin, this can be used to know the
actual number of chips, and update denali->max_banks.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
parent fa6134e5

drivers/mtd/nand/denali.c

+23 −29
Original line number Diff line number Diff line
@@ -85,33 +85,6 @@ static void index_addr(struct denali_nand_info *denali, 
	iowrite32(data, denali->flash_mem + 0x10);

}



/* Reset the flash controller */

static uint16_t denali_nand_reset(struct denali_nand_info *denali)

{

	int i;



	for (i = 0; i < denali->max_banks; i++)

		iowrite32(INTR__RST_COMP | INTR__TIME_OUT,

		denali->flash_reg + INTR_STATUS(i));



	for (i = 0; i < denali->max_banks; i++) {

		iowrite32(1 << i, denali->flash_reg + DEVICE_RESET);

		while (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &

			(INTR__RST_COMP | INTR__TIME_OUT)))

			cpu_relax();

		if (ioread32(denali->flash_reg + INTR_STATUS(i)) &

			INTR__TIME_OUT)

			dev_dbg(denali->dev,

			"NAND Reset operation timed out on bank %d\n", i);

	}



	for (i = 0; i < denali->max_banks; i++)

		iowrite32(INTR__RST_COMP | INTR__TIME_OUT,

			  denali->flash_reg + INTR_STATUS(i));



	return PASS;

}



/*

 * Use the configuration feature register to determine the maximum number of

 * banks that the hardware supports.
@@ -1053,7 +1026,28 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr, 
	return 0;

}



/* Initialization code to bring the device up to a known good state */

static void denali_reset_banks(struct denali_nand_info *denali)

{

	int i;



	denali_clear_irq_all(denali);



	for (i = 0; i < denali->max_banks; i++) {

		iowrite32(1 << i, denali->flash_reg + DEVICE_RESET);

		while (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &

			(INTR__RST_COMP | INTR__TIME_OUT)))

			cpu_relax();

		if (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &

		      INTR__INT_ACT))

			break;

	}



	dev_dbg(denali->dev, "%d chips connected\n", i);

	denali->max_banks = i;



	denali_clear_irq_all(denali);

}



static void denali_hw_init(struct denali_nand_info *denali)

{

	/*
@@ -1073,7 +1067,7 @@ static void denali_hw_init(struct denali_nand_info *denali) 
	denali->bbtskipbytes = ioread32(denali->flash_reg +

						SPARE_AREA_SKIP_BYTES);

	detect_max_banks(denali);

	denali_nand_reset(denali);

	denali_reset_banks(denali);

	iowrite32(0x0F, denali->flash_reg + RB_PIN_ENABLED);

	iowrite32(CHIP_EN_DONT_CARE__FLAG,

			denali->flash_reg + CHIP_ENABLE_DONT_CARE);

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