Re: [PATCH v3 4/6] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver

From: Dmitry Osipenko
Date: Sat Jun 09 2018 - 08:21:56 EST

On Saturday, 9 June 2018 00:51:01 MSK Stefan Agner wrote:
> On 01.06.2018 11:20, Dmitry Osipenko wrote:
> > On 01.06.2018 01:16, Stefan Agner wrote:
> >> Add support for the NAND flash controller found on NVIDIA
> >> Tegra 2 SoCs. This implementation does not make use of the
> >> command queue feature. Regular operations/data transfers are
> >> done in PIO mode. Page read/writes with hardware ECC make
> >> use of the DMA for data transfer.
> >>
> >> Signed-off-by: Lucas Stach <dev@xxxxxxxxxx>
> >> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
> >> ---
> >>
> >> MAINTAINERS | 7 +
> >> drivers/mtd/nand/raw/Kconfig | 6 +
> >> drivers/mtd/nand/raw/Makefile | 1 +
> >> drivers/mtd/nand/raw/tegra_nand.c | 1143 +++++++++++++++++++++++++++++
> >> 4 files changed, 1157 insertions(+)
> >> create mode 100644 drivers/mtd/nand/raw/tegra_nand.c
> >>
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index 58b9861ccf99..c2e5571c85d4 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -13844,6 +13844,13 @@ M: Laxman Dewangan <ldewangan@xxxxxxxxxx>
> >>
> >> S: Supported
> >> F: drivers/input/keyboard/tegra-kbc.c
> >>
> >> +TEGRA NAND DRIVER
> >> +M: Stefan Agner <stefan@xxxxxxxx>
> >> +M: Lucas Stach <dev@xxxxxxxxxx>
> >> +S: Maintained
> >> +F: Documentation/devicetree/bindings/mtd/nvidia-tegra20-nand.txt
> >> +F: drivers/mtd/nand/raw/tegra_nand.c
> >> +
> >>
> >> TEGRA PWM DRIVER
> >> M: Thierry Reding <thierry.reding@xxxxxxxxx>
> >> S: Supported
> >>
> >> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> >> index 19a2b283fbbe..e9093f52371e 100644
> >> --- a/drivers/mtd/nand/raw/Kconfig
> >> +++ b/drivers/mtd/nand/raw/Kconfig
> >> @@ -534,4 +534,10 @@ config MTD_NAND_MTK
> >>
> >> Enables support for NAND controller on MTK SoCs.
> >> This controller is found on mt27xx, mt81xx, mt65xx SoCs.
> >>
> >> +config MTD_NAND_TEGRA
> >> + tristate "Support for NAND controller on NVIDIA Tegra"
> >> + depends on ARCH_TEGRA || COMPILE_TEST
> >> + help
> >> + Enables support for NAND flash controller on NVIDIA Tegra SoC.
> >> +
> >>
> >> endif # MTD_NAND
> >>
> >> diff --git a/drivers/mtd/nand/raw/Makefile
> >> b/drivers/mtd/nand/raw/Makefile
> >> index 165b7ef9e9a1..d5a5f9832b88 100644
> >> --- a/drivers/mtd/nand/raw/Makefile
> >> +++ b/drivers/mtd/nand/raw/Makefile
> >> @@ -56,6 +56,7 @@ obj-$(CONFIG_MTD_NAND_HISI504) +=
> >> hisi504_nand.o
> >>
> >> obj-$(CONFIG_MTD_NAND_BRCMNAND) += brcmnand/
> >> obj-$(CONFIG_MTD_NAND_QCOM) += qcom_nandc.o
> >> obj-$(CONFIG_MTD_NAND_MTK) += mtk_ecc.o mtk_nand.o
> >>
> >> +obj-$(CONFIG_MTD_NAND_TEGRA) += tegra_nand.o
> >>
> >> nand-objs := nand_base.o nand_bbt.o nand_timings.o nand_ids.o
> >> nand-objs += nand_amd.o
> >>
> >> diff --git a/drivers/mtd/nand/raw/tegra_nand.c
> >> b/drivers/mtd/nand/raw/tegra_nand.c new file mode 100644
> >> index 000000000000..e9664f2938a3
> >> --- /dev/null
> >> +++ b/drivers/mtd/nand/raw/tegra_nand.c
> >> @@ -0,0 +1,1143 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Copyright (C) 2018 Stefan Agner <stefan@xxxxxxxx>
> >> + * Copyright (C) 2014-2015 Lucas Stach <dev@xxxxxxxxxx>
> >> + * Copyright (C) 2012 Avionic Design GmbH
> >> + */
> >> +
> >> +#include <linux/clk.h>
> >> +#include <linux/completion.h>
> >> +#include <linux/delay.h>
> >> +#include <linux/dma-mapping.h>
> >> +#include <linux/err.h>
> >> +#include <linux/gpio/consumer.h>
> >> +#include <linux/interrupt.h>
> >> +#include <linux/io.h>
> >> +#include <linux/module.h>
> >> +#include <linux/mtd/partitions.h>
> >> +#include <linux/mtd/rawnand.h>
> >> +#include <linux/of.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/reset.h>
> >> +
> >> +#define CMD 0x00
> >> +#define CMD_GO BIT(31)
> >> +#define CMD_CLE BIT(30)
> >> +#define CMD_ALE BIT(29)
> >> +#define CMD_PIO BIT(28)
> >> +#define CMD_TX BIT(27)
> >> +#define CMD_RX BIT(26)
> >> +#define CMD_SEC_CMD BIT(25)
> >> +#define CMD_AFT_DAT BIT(24)
> >> +#define CMD_TRANS_SIZE(x) (((x - 1) & 0xf) << 20)
> >> +#define CMD_A_VALID BIT(19)
> >> +#define CMD_B_VALID BIT(18)
> >> +#define CMD_RD_STATUS_CHK BIT(17)
> >> +#define CMD_RBSY_CHK BIT(16)
> >> +#define CMD_CE(x) BIT((8 + ((x) & 0x7)))
> >> +#define CMD_CLE_SIZE(x) (((x - 1) & 0x3) << 4)
> >> +#define CMD_ALE_SIZE(x) (((x - 1) & 0xf) << 0)
> >> +
> >> +#define STATUS 0x04
> >> +
> >> +#define ISR 0x08
> >> +#define ISR_CORRFAIL_ERR BIT(24)
> >> +#define ISR_UND BIT(7)
> >> +#define ISR_OVR BIT(6)
> >> +#define ISR_CMD_DONE BIT(5)
> >> +#define ISR_ECC_ERR BIT(4)
> >> +
> >> +#define IER 0x0c
> >> +#define IER_ERR_TRIG_VAL(x) (((x) & 0xf) << 16)
> >> +#define IER_UND BIT(7)
> >> +#define IER_OVR BIT(6)
> >> +#define IER_CMD_DONE BIT(5)
> >> +#define IER_ECC_ERR BIT(4)
> >> +#define IER_GIE BIT(0)
> >> +
> >> +#define CFG 0x10
> >> +#define CFG_HW_ECC BIT(31)
> >> +#define CFG_ECC_SEL BIT(30)
> >> +#define CFG_ERR_COR BIT(29)
> >> +#define CFG_PIPE_EN BIT(28)
> >> +#define CFG_TVAL_4 (0 << 24)
> >> +#define CFG_TVAL_6 (1 << 24)
> >> +#define CFG_TVAL_8 (2 << 24)
> >> +#define CFG_SKIP_SPARE BIT(23)
> >> +#define CFG_BUS_WIDTH_16 BIT(21)
> >> +#define CFG_COM_BSY BIT(20)
> >> +#define CFG_PS_256 (0 << 16)
> >> +#define CFG_PS_512 (1 << 16)
> >> +#define CFG_PS_1024 (2 << 16)
> >> +#define CFG_PS_2048 (3 << 16)
> >> +#define CFG_PS_4096 (4 << 16)
> >> +#define CFG_SKIP_SPARE_SIZE_4 (0 << 14)
> >> +#define CFG_SKIP_SPARE_SIZE_8 (1 << 14)
> >> +#define CFG_SKIP_SPARE_SIZE_12 (2 << 14)
> >> +#define CFG_SKIP_SPARE_SIZE_16 (3 << 14)
> >> +#define CFG_TAG_BYTE_SIZE(x) ((x) & 0xff)
> >> +
> >> +#define TIMING_1 0x14
> >> +#define TIMING_TRP_RESP(x) (((x) & 0xf) << 28)
> >> +#define TIMING_TWB(x) (((x) & 0xf) << 24)
> >> +#define TIMING_TCR_TAR_TRR(x) (((x) & 0xf) << 20)
> >> +#define TIMING_TWHR(x) (((x) & 0xf) << 16)
> >> +#define TIMING_TCS(x) (((x) & 0x3) << 14)
> >> +#define TIMING_TWH(x) (((x) & 0x3) << 12)
> >> +#define TIMING_TWP(x) (((x) & 0xf) << 8)
> >> +#define TIMING_TRH(x) (((x) & 0x3) << 4)
> >> +#define TIMING_TRP(x) (((x) & 0xf) << 0)
> >> +
> >> +#define RESP 0x18
> >> +
> >> +#define TIMING_2 0x1c
> >> +#define TIMING_TADL(x) ((x) & 0xf)
> >> +
> >> +#define CMD_1 0x20
> >> +#define CMD_2 0x24
> >> +#define ADDR_1 0x28
> >> +#define ADDR_2 0x2c
> >> +
> >> +#define DMA_CTRL 0x30
> >> +#define DMA_CTRL_GO BIT(31)
> >> +#define DMA_CTRL_IN (0 << 30)
> >> +#define DMA_CTRL_OUT BIT(30)
> >> +#define DMA_CTRL_PERF_EN BIT(29)
> >> +#define DMA_CTRL_IE_DONE BIT(28)
> >> +#define DMA_CTRL_REUSE BIT(27)
> >> +#define DMA_CTRL_BURST_1 (2 << 24)
> >> +#define DMA_CTRL_BURST_4 (3 << 24)
> >> +#define DMA_CTRL_BURST_8 (4 << 24)
> >> +#define DMA_CTRL_BURST_16 (5 << 24)
> >> +#define DMA_CTRL_IS_DONE BIT(20)
> >> +#define DMA_CTRL_EN_A BIT(2)
> >> +#define DMA_CTRL_EN_B BIT(1)
> >> +
> >> +#define DMA_CFG_A 0x34
> >> +#define DMA_CFG_B 0x38
> >> +
> >> +#define FIFO_CTRL 0x3c
> >> +#define FIFO_CTRL_CLR_ALL BIT(3)
> >> +
> >> +#define DATA_PTR 0x40
> >> +#define TAG_PTR 0x44
> >> +#define ECC_PTR 0x48
> >> +
> >> +#define DEC_STATUS 0x4c
> >> +#define DEC_STATUS_A_ECC_FAIL BIT(1)
> >> +#define DEC_STATUS_ERR_COUNT_MASK 0x00ff0000
> >> +#define DEC_STATUS_ERR_COUNT_SHIFT 16
> >> +
> >> +#define HWSTATUS_CMD 0x50
> >> +#define HWSTATUS_MASK 0x54
> >> +#define HWSTATUS_RDSTATUS_MASK(x) (((x) & 0xff) << 24)
> >> +#define HWSTATUS_RDSTATUS_VALUE(x) (((x) & 0xff) << 16)
> >> +#define HWSTATUS_RBSY_MASK(x) (((x) & 0xff) << 8)
> >> +#define HWSTATUS_RBSY_VALUE(x) (((x) & 0xff) << 0)
> >> +
> >> +#define BCH_CONFIG 0xcc
> >> +#define BCH_ENABLE BIT(0)
> >> +#define BCH_TVAL_4 (0 << 4)
> >> +#define BCH_TVAL_8 (1 << 4)
> >> +#define BCH_TVAL_14 (2 << 4)
> >> +#define BCH_TVAL_16 (3 << 4)
> >> +
> >> +#define DEC_STAT_RESULT 0xd0
> >> +#define DEC_STAT_BUF 0xd4
> >> +#define DEC_STAT_BUF_FAIL_SEC_FLAG_MASK 0xff000000
> >> +#define DEC_STAT_BUF_FAIL_SEC_FLAG_SHIFT 24
> >> +#define DEC_STAT_BUF_CORR_SEC_FLAG_MASK 0x00ff0000
> >> +#define DEC_STAT_BUF_CORR_SEC_FLAG_SHIFT 16
> >> +#define DEC_STAT_BUF_MAX_CORR_CNT_MASK 0x00001f00
> >> +#define DEC_STAT_BUF_MAX_CORR_CNT_SHIFT 8
> >> +
> >> +#define OFFSET(val, off) ((val) < (off) ? 0 : (val) - (off))
> >> +
> >> +#define SKIP_SPARE_BYTES 4
> >> +#define BITS_PER_STEP_RS 18
> >> +#define BITS_PER_STEP_BCH 13
> >> +
> >> +struct tegra_nand_controller {
> >> + struct nand_hw_control controller;
> >> + void __iomem *regs;
> >> + struct clk *clk;
> >> + struct device *dev;
> >> + struct completion command_complete;
> >> + struct completion dma_complete;
> >> + bool last_read_error;
> >> + int cur_chip;
> >> + struct nand_chip *chip;
> >> +};
> >> +
> >> +struct tegra_nand_chip {
> >> + struct nand_chip chip;
> >> + struct gpio_desc *wp_gpio;
> >> + struct mtd_oob_region tag;
> >> +};
> >> +
> >> +static inline struct tegra_nand_controller *to_tegra_ctrl(
> >> + struct nand_hw_control *hw_ctrl)
> >> +{
> >> + return container_of(hw_ctrl, struct tegra_nand_controller,
controller);
> >> +}
> >> +
> >> +static inline struct tegra_nand_chip *to_tegra_chip(struct nand_chip
> >> *chip) +{
> >> + return container_of(chip, struct tegra_nand_chip, chip);
> >> +}
> >> +
> >> +static int tegra_nand_ooblayout_rs_ecc(struct mtd_info *mtd, int
> >> section,
> >> + struct mtd_oob_region *oobregion)
> >> +{
> >> + struct nand_chip *chip = mtd_to_nand(mtd);
> >> + int bytes_per_step = DIV_ROUND_UP(BITS_PER_STEP_RS *
> >> chip->ecc.strength,
> >> + BITS_PER_BYTE);
> >> +
> >> + if (section > 0)
> >> + return -ERANGE;
> >> +
> >> + oobregion->offset = SKIP_SPARE_BYTES;
> >> + oobregion->length = round_up(bytes_per_step * chip->ecc.steps, 4);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int tegra_nand_ooblayout_rs_free(struct mtd_info *mtd, int
> >> section,
> >> + struct mtd_oob_region *oobregion)
> >> +{
> >> + struct nand_chip *chip = mtd_to_nand(mtd);
> >> + int bytes_per_step = DIV_ROUND_UP(BITS_PER_STEP_RS *
> >> chip->ecc.strength,
> >> + BITS_PER_BYTE);
> >> +
> >> + if (section > 0)
> >> + return -ERANGE;
> >> +
> >> + oobregion->offset = SKIP_SPARE_BYTES +
> >> + round_up(bytes_per_step * chip->ecc.steps, 4);
> >> + oobregion->length = mtd->oobsize - oobregion->offset;
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static const struct mtd_ooblayout_ops tegra_nand_oob_rs_ops = {
> >> + .ecc = tegra_nand_ooblayout_rs_ecc,
> >> + .free = tegra_nand_ooblayout_rs_free,
> >> +};
> >> +
> >> +static int tegra_nand_ooblayout_bch_ecc(struct mtd_info *mtd, int
> >> section,
> >> + struct mtd_oob_region *oobregion)
> >> +{
> >> + struct nand_chip *chip = mtd_to_nand(mtd);
> >> + int bytes_per_step = DIV_ROUND_UP(BITS_PER_STEP_BCH *
> >> chip->ecc.strength,
> >> + BITS_PER_BYTE);
> >> +
> >> + if (section > 0)
> >> + return -ERANGE;
> >> +
> >> + oobregion->offset = SKIP_SPARE_BYTES;
> >> + oobregion->length = round_up(bytes_per_step * chip->ecc.steps, 4);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int tegra_nand_ooblayout_bch_free(struct mtd_info *mtd, int
> >> section, + struct mtd_oob_region *oobregion)
> >> +{
> >> + struct nand_chip *chip = mtd_to_nand(mtd);
> >> + int bytes_per_step = DIV_ROUND_UP(BITS_PER_STEP_BCH *
> >> chip->ecc.strength,
> >> + BITS_PER_BYTE);
> >> +
> >> + if (section > 0)
> >> + return -ERANGE;
> >> +
> >> + oobregion->offset = SKIP_SPARE_BYTES +
> >> + round_up(bytes_per_step * chip->ecc.steps, 4);
> >> + oobregion->length = mtd->oobsize - oobregion->offset;
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +/*
> >> + * Layout with tag bytes is
> >> + *
> >> + *
> >> ------------------------------------------------------------------------
> >> -- + * | main area | skip bytes | tag bytes |
> >> parity | .. | + *
> >> ------------------------------------------------------------------------
> >> -- + *
> >> + * If not tag bytes are written, parity moves right after skip bytes!
> >> + */
> >> +static const struct mtd_ooblayout_ops tegra_nand_oob_bch_ops = {
> >> + .ecc = tegra_nand_ooblayout_bch_ecc,
> >> + .free = tegra_nand_ooblayout_bch_free,
> >> +};
> >> +
> >> +static irqreturn_t tegra_nand_irq(int irq, void *data)
> >> +{
> >> + struct tegra_nand_controller *ctrl = data;
> >> + u32 isr, dma;
> >> +
> >> + isr = readl_relaxed(ctrl->regs + ISR);
> >> + dma = readl_relaxed(ctrl->regs + DMA_CTRL);
> >> + dev_dbg(ctrl->dev, "isr %08x\n", isr);
> >> +
> >> + if (!isr && !(dma & DMA_CTRL_IS_DONE))
> >> + return IRQ_NONE;
> >> +
> >> + /*
> >> + * The bit name is somewhat missleading: This is also set when
> >> + * HW ECC was successful. The data sheet states:
> >> + * Correctable OR Un-correctable errors occurred in the DMA
transfer...
> >> + */
> >> + if (isr & ISR_CORRFAIL_ERR)
> >> + ctrl->last_read_error = true;
> >> +
> >> + if (isr & ISR_CMD_DONE)
> >> + complete(&ctrl->command_complete);
> >> +
> >> + if (isr & ISR_UND)
> >> + dev_err(ctrl->dev, "FIFO underrun\n");
> >> +
> >> + if (isr & ISR_OVR)
> >> + dev_err(ctrl->dev, "FIFO overrun\n");
> >> +
> >> + /* handle DMA interrupts */
> >> + if (dma & DMA_CTRL_IS_DONE) {
> >> + writel_relaxed(dma, ctrl->regs + DMA_CTRL);
> >> + complete(&ctrl->dma_complete);
> >> + }
> >> +
> >> + /* clear interrupts */
> >> + writel_relaxed(isr, ctrl->regs + ISR);
> >> +
> >> + return IRQ_HANDLED;
> >> +}
> >> +
> >> +static const char * const tegra_nand_reg_names[] = {
> >> + "COMMAND",
> >> + "STATUS",
> >> + "ISR",
> >> + "IER",
> >> + "CONFIG",
> >> + "TIMING",
> >> + NULL,
> >> + "TIMING2",
> >> + "CMD_REG1",
> >> + "CMD_REG2",
> >> + "ADDR_REG1",
> >> + "ADDR_REG2",
> >> + "DMA_MST_CTRL",
> >> + "DMA_CFG_A",
> >> + "DMA_CFG_B",
> >> + "FIFO_CTRL",
> >> +};
> >> +
> >> +static void tegra_nand_dump_reg(struct tegra_nand_controller *ctrl)
> >> +{
> >> + u32 reg;
> >> + int i;
> >> +
> >> + dev_err(ctrl->dev, "Tegra NAND controller register dump\n");
> >> + for (i = 0; i < ARRAY_SIZE(tegra_nand_reg_names); i++) {
> >> + const char *reg_name = tegra_nand_reg_names[i];
> >> +
> >> + if (!reg_name)
> >> + continue;
> >> +
> >> + reg = readl_relaxed(ctrl->regs + (i * 4));
> >> + dev_err(ctrl->dev, "%s: 0x%08x\n", reg_name, reg);
> >> + }
> >> +}
> >> +
> >> +static int tegra_nand_cmd(struct nand_chip *chip,
> >> + const struct nand_subop *subop)
> >> +{
> >> + const struct nand_op_instr *instr;
> >> + const struct nand_op_instr *instr_data_in = NULL;
> >> + struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
> >> + unsigned int op_id, size = 0, offset = 0;
> >> + bool first_cmd = true;
> >> + u32 reg, cmd = 0;
> >> + int ret;
> >> +
> >> + for (op_id = 0; op_id < subop->ninstrs; op_id++) {
> >> + unsigned int naddrs, i;
> >> + const u8 *addrs;
> >> + u32 addr1 = 0, addr2 = 0;
> >> +
> >> + instr = &subop->instrs[op_id];
> >> +
> >> + switch (instr->type) {
> >> + case NAND_OP_CMD_INSTR:
> >> + if (first_cmd) {
> >> + cmd |= CMD_CLE;
> >> + writel_relaxed(instr->ctx.cmd.opcode,
> >> + ctrl->regs + CMD_1);
> >> + } else {
> >> + cmd |= CMD_SEC_CMD;
> >> + writel_relaxed(instr->ctx.cmd.opcode,
> >> + ctrl->regs + CMD_2);
> >> + }
> >> + first_cmd = false;
> >> + break;
> >> + case NAND_OP_ADDR_INSTR:
> >> + offset = nand_subop_get_addr_start_off(subop, op_id);
> >> + naddrs = nand_subop_get_num_addr_cyc(subop, op_id);
> >> + addrs = &instr->ctx.addr.addrs[offset];
> >> +
> >> + cmd |= CMD_ALE | CMD_ALE_SIZE(naddrs);
> >> + for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
> >> + addr1 |= *addrs++ << (BITS_PER_BYTE * i);
> >> + naddrs -= i;
> >> + for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
> >> + addr2 |= *addrs++ << (BITS_PER_BYTE * i);
> >> + writel_relaxed(addr1, ctrl->regs + ADDR_1);
> >> + writel_relaxed(addr2, ctrl->regs + ADDR_2);
> >> + break;
> >> +
> >> + case NAND_OP_DATA_IN_INSTR:
> >> + size = nand_subop_get_data_len(subop, op_id);
> >> + offset = nand_subop_get_data_start_off(subop, op_id);
> >> +
> >> + cmd |= CMD_TRANS_SIZE(size) | CMD_PIO | CMD_RX |
> >> + CMD_A_VALID;
> >> +
> >> + instr_data_in = instr;
> >> + break;
> >> +
> >> + case NAND_OP_DATA_OUT_INSTR:
> >> + size = nand_subop_get_data_len(subop, op_id);
> >> + offset = nand_subop_get_data_start_off(subop, op_id);
> >> +
> >> + cmd |= CMD_TRANS_SIZE(size) | CMD_PIO | CMD_TX |
> >> + CMD_A_VALID;
> >> +
> >> + memcpy(&reg, instr->ctx.data.buf.out + offset, size);
> >> + writel_relaxed(reg, ctrl->regs + RESP);
> >> +
> >> + break;
> >> + case NAND_OP_WAITRDY_INSTR:
> >> + cmd |= CMD_RBSY_CHK;
> >> + break;
> >> +
> >> + }
> >> + }
> >> +
> >> + cmd |= CMD_GO | CMD_CE(ctrl->cur_chip);
> >> + writel_relaxed(cmd, ctrl->regs + CMD);
> >> + ret = wait_for_completion_timeout(&ctrl->command_complete,
> >> + msecs_to_jiffies(500));
> >> + if (!ret) {
> >> + dev_err(ctrl->dev, "CMD timeout\n");
> >> + tegra_nand_dump_reg(ctrl);
> >> + return -ETIMEDOUT;
> >> + }
> >
> > - wait_for_completion_timeout() could fail
>
> Not according to:
> https://elixir.bootlin.com/linux/latest/source/kernel/sched/completion.c#L14
> 0 https://www.kernel.org/doc/Documentation/scheduler/completion.txt
>
> Afaik, only the _interruptible variant can fail.

Okay.

> Btw, maybe we should use the _io variant?

Looks like the _io variant is something specific to block/FS subsys and
shouldn't be used by the drivers.

> > - HW shall be reset
> > - completion shall be re-inited because IRQ could fire just after the
> > completion timeout
> >
> > I'd write it something like this:
> >
> > #define INT_MASK (IER_UND | IER_OVR | IER_CMD_DONE | IER_GIE)
> >
> > #define HWSTATUS_MASK (HWSTATUS_RDSTATUS_MASK(1) | \
> >
> > HWSTATUS_RDSTATUS_VALUE(0) | \
> > HWSTATUS_RBSY_MASK(NAND_STATUS_READY) | \
> > HWSTATUS_RBSY_VALUE(NAND_STATUS_READY))
> >
> > #define HW_TIMEOUT 500
> >
> > void tegra_nand_controller_reset(struct tegra_nand_controller *ctrl)
> > {
> >
> > int err;
> >
> > disable_irq(ctrl->irq);
> >
> > err = reset_control_reset(ctrl->rst);
> > if (err) {
> >
> > dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
> > msleep(HW_TIMEOUT);
> >
> > }
> >
> > writel_relaxed(NAND_CMD_STATUS, ctrl->regs + HWSTATUS_CMD);
> > writel_relaxed(HWSTATUS_MASK, ctrl->regs + HWSTATUS_MASK);
> > writel_relaxed(INT_MASK, ctrl->regs + ISR);
>
> If we do a controller reset, there is much more state than that which
> needs to be restored. A lot of it is not readily available currently
> (timing, ECC settings...)
>
> That seems a lot of work for a code path I do not intend to ever use :-)

Are you sure that resetting HW resets the timing and other registers
configuration? Reset implementation is HW-specific, like for example in a case
of a video decoder the registers state is re-intialized on HW reset, but
registers configuration is untouched in a case of resetting GPU. I'd suggest
to check whether NAND controller resetting affects the HW configuration.