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mtd: rawnand: denali: remove ->dev_ready() hook 

The Denali NAND IP has no way to read out the current signal level
of the R/B# pin. Instead, denali_dev_ready() checks if the R/B#
transition has already happened. (The INTR__INT_ACT interrupt is
asserted at the rising edge of the R/B# pin.) It is not a correct
way to implement the ->dev_ready() hook.

In fact, it has a drawback; in the nand_scan_ident phase, the chip
detection iterates over maxchips until it fails to find a homogeneous
chip. For the last loop, nand_reset() fails if no chip is there.

If ->dev_ready hook exists, nand_command(_lp) calls nand_wait_ready()
after NAND_CMD_RESET. However, we know denali_dev_ready() never
returns 1 unless there exists a chip that toggles R/B# in that chip
select. Then, nand_wait_ready() just ends up with wasting 400 msec,
in the end, shows the "timeout while waiting for chip to become ready"
warning.

Let's remove the mis-implemented dev_ready hook, and fallback to
sending the NAND_CMD_STATUS and nand_wait_status_ready(), which
bails out more quickly.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This commit is contained in:
Masahiro Yamada 2018-11-28 14:27:36 +09:00 committed by Miquel Raynal
parent 1b489effdb
commit a2a05c2f53
1 changed files with 1 additions and 22 deletions
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23
drivers/mtd/nand/raw/denali.c
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@ -204,18 +204,6 @@ static uint32_t denali_wait_for_irq(struct denali_nand_info *denali,
return denali->irq_status;
}
static uint32_t denali_check_irq(struct denali_nand_info *denali)
{
unsigned long flags;
uint32_t irq_status;
spin_lock_irqsave(&denali->irq_lock, flags);
irq_status = denali->irq_status;
spin_unlock_irqrestore(&denali->irq_lock, flags);
return irq_status;
}
static void denali_read_buf(struct nand_chip *chip, uint8_t *buf, int len)
{
struct mtd_info *mtd = nand_to_mtd(chip);
@ -288,8 +276,7 @@ static void denali_cmd_ctrl(struct nand_chip *chip, int dat, unsigned int ctrl)
return;
/*
* Some commands are followed by chip->legacy.dev_ready or
* chip->legacy.waitfunc.
* Some commands are followed by chip->legacy.waitfunc.
* irq_status must be cleared here to catch the R/B# interrupt later.
*/
if (ctrl & NAND_CTRL_CHANGE)
@ -298,13 +285,6 @@ static void denali_cmd_ctrl(struct nand_chip *chip, int dat, unsigned int ctrl)
denali->host_write(denali, DENALI_BANK(denali) | type, dat);
}
static int denali_dev_ready(struct nand_chip *chip)
{
struct denali_nand_info *denali = mtd_to_denali(nand_to_mtd(chip));
return !!(denali_check_irq(denali) & INTR__INT_ACT);
}
static int denali_check_erased_page(struct mtd_info *mtd,
struct nand_chip *chip, uint8_t *buf,
unsigned long uncor_ecc_flags,
@ -1360,7 +1340,6 @@ int denali_init(struct denali_nand_info *denali)
chip->legacy.read_byte = denali_read_byte;
chip->legacy.write_byte = denali_write_byte;
chip->legacy.cmd_ctrl = denali_cmd_ctrl;
chip->legacy.dev_ready = denali_dev_ready;
chip->legacy.waitfunc = denali_waitfunc;
if (features & FEATURES__INDEX_ADDR) {