Commit 5fb3dc11 authored Nov 28, 2018 by Masahiro Yamada Committed by Miquel Raynal Dec 07, 2018

mtd: rawnand: denali: remove denali_reset_banks()



In nand_scan_ident(), the controller driver resets every NAND chip.
This is done by sending NAND_CMD_RESET. The Denali IP provides
another way to do the equivalent thing; if a bit is set in the
DEVICE_RESET register, the controller sends the RESET command to
the corresponding device. denali_reset_banks() uses it to reset
all devices beforehand.

This redundant reset sequence was needed to know the actual number
of chips before calling nand_scan_ident(); if DEVICE_RESET fails,
there is no chip in that chip select. Then, denali_reset_banks()
sets denali->max_banks to the number of detected chips.

As commit f486287d ("mtd: nand: denali: fix bank reset function
to detect the number of chips") explained, nand_scan_ident() issued
Set Features (0xEF) command to all CS lines, some of which may not be
connected with a chip. Then, the driver would wait for R/B# response,
which never happens.

This problem was solved by commit 107b7d6a ("mtd: rawnand: avoid
setting again the timings to mode 0 after a reset"). In the current
code, nand_setup_data_interface() is called from nand_scan_tail(),
which is invoked after the chip detection.

Now, we can really remove the redundant denali_nand_banks() by simply
passing the maximum number of chip selects supported by this IP
(typically 4 or 8) to nand_scan(). Let's leave all the chip detection
process to nand_scan_ident().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

parent a2a05c2f

drivers/mtd/nand/raw/denali.c

+0 −29

Original line number	Diff line number	Diff line
		@@ -1045,29 +1045,6 @@ static int denali_setup_data_interface(struct nand_chip *chip, int chipnr,
		return 0;
		}

		static void denali_reset_banks(struct denali_nand_info *denali)
		{
		u32 irq_status;
		int i;

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

		denali_reset_irq(denali);

		iowrite32(DEVICE_RESET__BANK(i),
		denali->reg + DEVICE_RESET);

		irq_status = denali_wait_for_irq(denali,
		INTR__RST_COMP \| INTR__INT_ACT \| INTR__TIME_OUT);
		if (!(irq_status & INTR__INT_ACT))
		break;
		}

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

		static void denali_hw_init(struct denali_nand_info *denali)
		{
		/*
		@@ -1322,12 +1299,6 @@ int denali_init(struct denali_nand_info *denali)
		}

		denali_enable_irq(denali);
		denali_reset_banks(denali);
		if (!denali->max_banks) {
		/* Error out earlier if no chip is found for some reasons. */
		ret = -ENODEV;
		goto disable_irq;
		}

		denali->active_bank = DENALI_INVALID_BANK;

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