| Message ID | 1536305309-28026-2-git-send-email-yamada.masahiro@socionext.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | mtd: rawnand: denali: clean-up unnecessary hook and device reset | expand |
Hi Masahiro, Masahiro Yamada <yamada.masahiro@socionext.com> wrote on Fri, 7 Sep 2018 16:28:28 +0900: > 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> > --- Both patches applied on nand/next. Thanks, Miquèl
diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c index f88a5dc..f069184 100644 --- a/drivers/mtd/nand/raw/denali.c +++ b/drivers/mtd/nand/raw/denali.c @@ -203,18 +203,6 @@ 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 mtd_info *mtd, uint8_t *buf, int len) { struct denali_nand_info *denali = mtd_to_denali(mtd); @@ -294,7 +282,7 @@ static void denali_cmd_ctrl(struct mtd_info *mtd, int dat, unsigned int ctrl) return; /* - * Some commands are followed by chip->dev_ready or chip->waitfunc. + * Some commands are followed by chip->waitfunc. * irq_status must be cleared here to catch the R/B# interrupt later. */ if (ctrl & NAND_CTRL_CHANGE) @@ -303,13 +291,6 @@ static void denali_cmd_ctrl(struct mtd_info *mtd, int dat, unsigned int ctrl) denali->host_write(denali, DENALI_BANK(denali) | type, dat); } -static int denali_dev_ready(struct mtd_info *mtd) -{ - struct denali_nand_info *denali = mtd_to_denali(mtd); - - 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, @@ -1349,7 +1330,6 @@ int denali_init(struct denali_nand_info *denali) chip->write_byte = denali_write_byte; chip->read_word = denali_read_word; chip->cmd_ctrl = denali_cmd_ctrl; - chip->dev_ready = denali_dev_ready; chip->waitfunc = denali_waitfunc; if (features & FEATURES__INDEX_ADDR) {
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> --- drivers/mtd/nand/raw/denali.c | 22 +--------------------- 1 file changed, 1 insertion(+), 21 deletions(-) -- 2.7.4