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

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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: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
This commit is contained in:
Masahiro Yamada 2017-06-13 22:45:40 +09:00 committed by Boris Brezillon
parent fa6134e545
commit f486287d23
1 changed files with 23 additions and 29 deletions
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52
drivers/mtd/nand/denali.c
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@ -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);