Re: [PATCH] spi: Replace `dummy.nbytes` with `dummy.ncycles`

Serge Semin
2022-09-25T22:03:53Z

Hello Sergiu

On Sun, Sep 11, 2022 at 08:45:53PM +0300, Sergiu Moga wrote:
> In order to properly represent the hardware functionality
> in the core, avoid reconverting the number of dummy cycles
> to the number of bytes and only work with the former.
> Instead, let the drivers that do need this conversion do
> it themselves.
>
> Signed-off-by: Sergiu Moga <sergiu.moga@microchip.com>
> ---
> drivers/mtd/spi-nor/core.c | 22 ++++----------

[...]

> drivers/spi/spi-dw-core.c | 10 +++++--

[...]

> drivers/spi/spi-mem.c | 27 +++++++++++------

[...]

> drivers/spi/spi-mtk-nor.c | 48 +++++++++++++++++--------------

[...]

> drivers/spi/spi-zynq-qspi.c | 15 ++++++----
> drivers/spi/spi-zynqmp-gqspi.c | 8 ++++--
> include/linux/spi/spi-mem.h | 10 +++----
> 25 files changed, 234 insertions(+), 147 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index f2c64006f8d7..cc8ca824f912 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -88,7 +88,7 @@ void spi_nor_spimem_setup_op(const struct spi_nor *nor,
> if (op->addr.nbytes)
> op->addr.buswidth = spi_nor_get_protocol_addr_nbits(proto);
>

> - if (op->dummy.nbytes)
> + if (op->dummy.ncycles)
> op->dummy.buswidth = spi_nor_get_protocol_addr_nbits(proto);
>
> if (op->data.nbytes)
> @@ -106,9 +106,6 @@ void spi_nor_spimem_setup_op(const struct spi_nor *nor,
> op->dummy.dtr = true;
> op->data.dtr = true;
>
> - /* 2 bytes per clock cycle in DTR mode. */
> - op->dummy.nbytes *= 2;
> -
> ext = spi_nor_get_cmd_ext(nor, op);
> op->cmd.opcode = (op->cmd.opcode << 8) | ext;
> op->cmd.nbytes = 2;
> @@ -207,10 +204,7 @@ static ssize_t spi_nor_spimem_read_data(struct spi_nor *nor, loff_t from,
>
> spi_nor_spimem_setup_op(nor, &op, nor->read_proto);
>
> - /* convert the dummy cycles to the number of bytes */
> - op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> - if (spi_nor_protocol_is_dtr(nor->read_proto))
> - op.dummy.nbytes *= 2;
> + op.dummy.ncycles = nor->read_dummy;

So according to this modification and what is done in the rest of the
patch, the dummy part of the SPI-mem operations now contains the number
of cycles only. Am I right to think that it means a number of dummy
clock oscillations? (Judging from what I've seen in the HW-manuals of
the SPI NOR memory devices most likely I am...) If so the "ncycles" field
is now free from the "data" semantic. Then what is the meaning of the
"buswidth and "dtr" fields in the spi_mem_op.dummy field?

>
> usebouncebuf = spi_nor_spimem_bounce(nor, &op);
>
> @@ -455,7 +449,7 @@ int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
>
> if (nor->reg_proto == SNOR_PROTO_8_8_8_DTR) {
> op.addr.nbytes = nor->params->rdsr_addr_nbytes;
> - op.dummy.nbytes = nor->params->rdsr_dummy;
> + op.dummy.ncycles = nor->params->rdsr_dummy;
> /*
> * We don't want to read only one byte in DTR mode. So,
> * read 2 and then discard the second byte.
> @@ -1913,10 +1907,7 @@ static int spi_nor_spimem_check_readop(struct spi_nor *nor,
>
> spi_nor_spimem_setup_op(nor, &op, read->proto);
>
> - /* convert the dummy cycles to the number of bytes */
> - op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> - if (spi_nor_protocol_is_dtr(nor->read_proto))
> - op.dummy.nbytes *= 2;
> + op.dummy.ncycles = nor->read_dummy;
>
> return spi_nor_spimem_check_op(nor, &op);
> }
> @@ -3034,10 +3025,7 @@ static int spi_nor_create_read_dirmap(struct spi_nor *nor)
>
> spi_nor_spimem_setup_op(nor, op, nor->read_proto);
>
> - /* convert the dummy cycles to the number of bytes */
> - op->dummy.nbytes = (nor->read_dummy * op->dummy.buswidth) / 8;
> - if (spi_nor_protocol_is_dtr(nor->read_proto))
> - op->dummy.nbytes *= 2;
> + op->dummy.ncycles = nor->read_dummy;
>
> /*
> * Since spi_nor_spimem_setup_op() only sets buswidth when the number

[...]

> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index f87d97ccd2d6..0ba5c7d0e66e 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -498,13 +498,17 @@ static bool dw_spi_supports_mem_op(struct spi_mem *mem,
> static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
> {
> unsigned int i, j, len;
> - u8 *out;
> + u8 *out, dummy_nbytes;
>
> /*
> * Calculate the total length of the EEPROM command transfer and
> * either use the pre-allocated buffer or create a temporary one.
> */
> - len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;

> + dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;

1. What about using the BITS_PER_BYTE macro (linux/bits.h) here? Since
you are adding a similar modification to so many drivers what about using
that macro there too?

2. buswidth is supposed to be always 1 in this driver (see the
dw_spi_supports_mem_op() method). So it can be dropped from the
statement above.

3. Since the ncycles now contains a number of clock cycles there is no
point in taking the SPI bus-width into account at all. What is
meaningful is how many oscillations are supposed to be placed on the
CLK line before the data is available. So the op->dummy.ncycles /
BITS_PER_BYTE statement would be more appropriate here in any case.

> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

DTR is unsupported by the controller. See, no spi_controller_mem_caps
initialized. So this part is redundant. The same is most likely
applicable for some of the DTR-related updates in this patch too
since the spi_controller_mem_caps structure is initialized in a few
drivers only.

> +
> + len = op->cmd.nbytes + op->addr.nbytes + dummy_nbytes;
> if (op->data.dir == SPI_MEM_DATA_OUT)
> len += op->data.nbytes;
>
> @@ -525,7 +529,7 @@ static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
> out[i] = DW_SPI_GET_BYTE(op->cmd.opcode, op->cmd.nbytes - i - 1);
> for (j = 0; j < op->addr.nbytes; ++i, ++j)
> out[i] = DW_SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j - 1);
> - for (j = 0; j < op->dummy.nbytes; ++i, ++j)
> + for (j = 0; j < dummy_nbytes; ++i, ++j)
> out[i] = 0x0;
>
> if (op->data.dir == SPI_MEM_DATA_OUT)

[...]

> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index 0c79193d9697..7b204963bb62 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -149,7 +149,7 @@ static bool spi_mem_check_buswidth(struct spi_mem *mem,
> spi_check_buswidth_req(mem, op->addr.buswidth, true))
> return false;
>
> - if (op->dummy.nbytes &&
> + if (op->dummy.ncycles &&
> spi_check_buswidth_req(mem, op->dummy.buswidth, true))
> return false;
>
> @@ -202,7 +202,7 @@ static int spi_mem_check_op(const struct spi_mem_op *op)
> return -EINVAL;
>
> if ((op->addr.nbytes && !op->addr.buswidth) ||
> - (op->dummy.nbytes && !op->dummy.buswidth) ||
> + (op->dummy.ncycles && !op->dummy.buswidth) ||
> (op->data.nbytes && !op->data.buswidth))
> return -EINVAL;
>
> @@ -315,7 +315,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)

> struct spi_controller *ctlr = mem->spi->controller;
> struct spi_transfer xfers[4] = { };
> struct spi_message msg;
> - u8 *tmpbuf;
> + u8 *tmpbuf, dummy_nbytes;
> int ret;

Reverse xmas tree order?

>
> ret = spi_mem_check_op(op);
> @@ -343,7 +343,11 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> return ret;
> }
>

> - tmpbufsize = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
> + dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;

So ncycles now indeed is a number of CLK line oscillations. This most
likely will break the SPI Nand driver then, which still passes the
number of bytes to the SPI_MEM_OP_DUMMY() macro.

> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

Generic SPI-mem ops don't take the DTR mode into account. So I don't
see this necessary.

> +
> + tmpbufsize = op->cmd.nbytes + op->addr.nbytes + dummy_nbytes;
>
> /*
> * Allocate a buffer to transmit the CMD, ADDR cycles with kmalloc() so
> @@ -379,15 +383,15 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> totalxferlen += op->addr.nbytes;
> }
>
> - if (op->dummy.nbytes) {
> - memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> + if (dummy_nbytes) {
> + memset(tmpbuf + op->addr.nbytes + 1, 0xff, dummy_nbytes);
> xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> - xfers[xferpos].len = op->dummy.nbytes;
> + xfers[xferpos].len = dummy_nbytes;
> xfers[xferpos].tx_nbits = op->dummy.buswidth;
> xfers[xferpos].dummy_data = 1;
> spi_message_add_tail(&xfers[xferpos], &msg);
> xferpos++;
> - totalxferlen += op->dummy.nbytes;
> + totalxferlen += dummy_nbytes;
> }
>
> if (op->data.nbytes) {
> @@ -456,12 +460,17 @@ int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
> {

> struct spi_controller *ctlr = mem->spi->controller;
> size_t len;
> + u8 dummy_nbytes;

reverse xmas tree?

>
> if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size)
> return ctlr->mem_ops->adjust_op_size(mem, op);
>
> + dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;
> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;
> +
> if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op) {
> - len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
> + len = op->cmd.nbytes + op->addr.nbytes + dummy_nbytes;
>
> if (len > spi_max_transfer_size(mem->spi))
> return -EINVAL;

[...]

> diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
> index d167699a1a96..f6870c6e911a 100644
> --- a/drivers/spi/spi-mtk-nor.c
> +++ b/drivers/spi/spi-mtk-nor.c
> @@ -171,23 +171,18 @@ static bool need_bounce(struct mtk_nor *sp, const struct spi_mem_op *op)
>
> static bool mtk_nor_match_read(const struct spi_mem_op *op)
> {
> - int dummy = 0;
> -
> - if (op->dummy.nbytes)
> - dummy = op->dummy.nbytes * BITS_PER_BYTE / op->dummy.buswidth;
> -
> if ((op->data.buswidth == 2) || (op->data.buswidth == 4)) {
> if (op->addr.buswidth == 1)
> - return dummy == 8;
> + return op->dummy.ncycles == 8;
> else if (op->addr.buswidth == 2)
> - return dummy == 4;
> + return op->dummy.ncycles == 4;
> else if (op->addr.buswidth == 4)
> - return dummy == 6;
> + return op->dummy.ncycles == 6;
> } else if ((op->addr.buswidth == 1) && (op->data.buswidth == 1)) {
> if (op->cmd.opcode == 0x03)
> - return dummy == 0;
> + return op->dummy.ncycles == 0;
> else if (op->cmd.opcode == 0x0b)
> - return dummy == 8;
> + return op->dummy.ncycles == 8;
> }
> return false;
> }
> @@ -195,6 +190,10 @@ static bool mtk_nor_match_read(const struct spi_mem_op *op)
> static bool mtk_nor_match_prg(const struct spi_mem_op *op)
> {
> int tx_len, rx_len, prg_len, prg_left;

> + u8 dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;
> +

IMO it's better to move the initialization statement to a separate
line here.

> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

Does the MTK SPI driver support DTR? AFAICS it doesn't.

>
> // prg mode is spi-only.
> if ((op->cmd.buswidth > 1) || (op->addr.buswidth > 1) ||
> @@ -205,7 +204,7 @@ static bool mtk_nor_match_prg(const struct spi_mem_op *op)
>
> if (op->data.dir == SPI_MEM_DATA_OUT) {
> // count dummy bytes only if we need to write data after it
> - tx_len += op->dummy.nbytes;
> + tx_len += dummy_nbytes;
>
> // leave at least one byte for data
> if (tx_len > MTK_NOR_REG_PRGDATA_MAX)
> @@ -221,7 +220,7 @@ static bool mtk_nor_match_prg(const struct spi_mem_op *op)
> return false;
>
> rx_len = op->data.nbytes;
> - prg_left = MTK_NOR_PRG_CNT_MAX / 8 - tx_len - op->dummy.nbytes;
> + prg_left = MTK_NOR_PRG_CNT_MAX / 8 - tx_len - dummy_nbytes;
> if (prg_left > MTK_NOR_REG_SHIFT_MAX + 1)
> prg_left = MTK_NOR_REG_SHIFT_MAX + 1;
> if (rx_len > prg_left) {
> @@ -230,11 +229,11 @@ static bool mtk_nor_match_prg(const struct spi_mem_op *op)
> rx_len = prg_left;
> }
>
> - prg_len = tx_len + op->dummy.nbytes + rx_len;
> + prg_len = tx_len + dummy_nbytes + rx_len;
> if (prg_len > MTK_NOR_PRG_CNT_MAX / 8)
> return false;
> } else {
> - prg_len = tx_len + op->dummy.nbytes;
> + prg_len = tx_len + dummy_nbytes;
> if (prg_len > MTK_NOR_PRG_CNT_MAX / 8)
> return false;
> }
> @@ -244,15 +243,19 @@ static bool mtk_nor_match_prg(const struct spi_mem_op *op)
> static void mtk_nor_adj_prg_size(struct spi_mem_op *op)
> {
> int tx_len, tx_left, prg_left;

> + u8 dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;
> +
> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

ditto

>
> tx_len = op->cmd.nbytes + op->addr.nbytes;
> if (op->data.dir == SPI_MEM_DATA_OUT) {
> - tx_len += op->dummy.nbytes;
> + tx_len += dummy_nbytes;
> tx_left = MTK_NOR_REG_PRGDATA_MAX + 1 - tx_len;
> if (op->data.nbytes > tx_left)
> op->data.nbytes = tx_left;
> } else if (op->data.dir == SPI_MEM_DATA_IN) {
> - prg_left = MTK_NOR_PRG_CNT_MAX / 8 - tx_len - op->dummy.nbytes;
> + prg_left = MTK_NOR_PRG_CNT_MAX / 8 - tx_len - dummy_nbytes;
> if (prg_left > MTK_NOR_REG_SHIFT_MAX + 1)
> prg_left = MTK_NOR_REG_SHIFT_MAX + 1;
> if (op->data.nbytes > prg_left)
> @@ -312,7 +315,7 @@ static bool mtk_nor_supports_op(struct spi_mem *mem,
> break;
> case SPI_MEM_DATA_OUT:
> if ((op->addr.buswidth == 1) &&
> - (op->dummy.nbytes == 0) &&
> + (op->dummy.ncycles == 0) &&
> (op->data.buswidth == 1))
> return true;
> break;
> @@ -515,17 +518,20 @@ static int mtk_nor_spi_mem_prg(struct mtk_nor *sp, const struct spi_mem_op *op)
> int tx_len, prg_len;
> int i, ret;
> void __iomem *reg;

> - u8 bufbyte;
> + u8 bufbyte, dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;
> +
> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

ditto

>
> tx_len = op->cmd.nbytes + op->addr.nbytes;
>
> // count dummy bytes only if we need to write data after it
> if (op->data.dir == SPI_MEM_DATA_OUT)
> - tx_len += op->dummy.nbytes + op->data.nbytes;
> + tx_len += dummy_nbytes + op->data.nbytes;
> else if (op->data.dir == SPI_MEM_DATA_IN)
> rx_len = op->data.nbytes;
>
> - prg_len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes +
> + prg_len = op->cmd.nbytes + op->addr.nbytes + dummy_nbytes +
> op->data.nbytes;
>
> // an invalid op may reach here if the caller calls exec_op without
> @@ -550,7 +556,7 @@ static int mtk_nor_spi_mem_prg(struct mtk_nor *sp, const struct spi_mem_op *op)
> }
>
> if (op->data.dir == SPI_MEM_DATA_OUT) {
> - for (i = 0; i < op->dummy.nbytes; i++, reg_offset--) {
> + for (i = 0; i < dummy_nbytes; i++, reg_offset--) {
> reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
> writeb(0, reg);
> }

[...]

> diff --git a/drivers/spi/spi-zynq-qspi.c b/drivers/spi/spi-zynq-qspi.c
> index 78f31b61a2aa..84b7db85548c 100644
> --- a/drivers/spi/spi-zynq-qspi.c
> +++ b/drivers/spi/spi-zynq-qspi.c
> @@ -527,7 +527,10 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
> {
> struct zynq_qspi *xqspi = spi_controller_get_devdata(mem->spi->master);
> int err = 0, i;
> - u8 *tmpbuf;
> + u8 *tmpbuf, dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;

Separate line?

> +
> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

Is DTR supported by the driver?

>
> dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
> op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
> @@ -568,17 +571,17 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
> err = -ETIMEDOUT;
> }
>
> - if (op->dummy.nbytes) {
> - tmpbuf = kzalloc(op->dummy.nbytes, GFP_KERNEL);
> + if (dummy_nbytes) {
> + tmpbuf = kzalloc(dummy_nbytes, GFP_KERNEL);
> if (!tmpbuf)
> return -ENOMEM;
>
> - memset(tmpbuf, 0xff, op->dummy.nbytes);
> + memset(tmpbuf, 0xff, dummy_nbytes);
> reinit_completion(&xqspi->data_completion);
> xqspi->txbuf = tmpbuf;
> xqspi->rxbuf = NULL;
> - xqspi->tx_bytes = op->dummy.nbytes;
> - xqspi->rx_bytes = op->dummy.nbytes;
> + xqspi->tx_bytes = dummy_nbytes;
> + xqspi->rx_bytes = dummy_nbytes;
> zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
> zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
> ZYNQ_QSPI_IXR_RXTX_MASK);
> diff --git a/drivers/spi/spi-zynqmp-gqspi.c b/drivers/spi/spi-zynqmp-gqspi.c
> index c760aac070e5..b41abadef9a6 100644
> --- a/drivers/spi/spi-zynqmp-gqspi.c
> +++ b/drivers/spi/spi-zynqmp-gqspi.c
> @@ -948,6 +948,10 @@ static int zynqmp_qspi_exec_op(struct spi_mem *mem,
> u32 genfifoentry = 0;
> u16 opcode = op->cmd.opcode;
> u64 opaddr;

> + u8 dummy_nbytes = (op->dummy.ncycles * op->dummy.buswidth) / 8;
> +
> + if (op->dummy.dtr)
> + dummy_nbytes *= 2;

ditto

>
> dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
> op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
> @@ -1006,14 +1010,14 @@ static int zynqmp_qspi_exec_op(struct spi_mem *mem,
> }
> }
>
> - if (op->dummy.nbytes) {
> + if (dummy_nbytes) {
> xqspi->txbuf = NULL;
> xqspi->rxbuf = NULL;
> /*
> * xqspi->bytes_to_transfer here represents the dummy circles
> * which need to be sent.
> */
> - xqspi->bytes_to_transfer = op->dummy.nbytes * 8 / op->dummy.buswidth;
> + xqspi->bytes_to_transfer = dummy_nbytes;
> xqspi->bytes_to_receive = 0;
> /*
> * Using op->data.buswidth instead of op->dummy.buswidth here because
> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
> index 2ba044d0d5e5..5fd45800af03 100644
> --- a/include/linux/spi/spi-mem.h
> +++ b/include/linux/spi/spi-mem.h
> @@ -29,9 +29,9 @@
>
> #define SPI_MEM_OP_NO_ADDR { }
>

> -#define SPI_MEM_OP_DUMMY(__nbytes, __buswidth) \
> +#define SPI_MEM_OP_DUMMY(__ncycles, __buswidth) \
> { \

> - .nbytes = __nbytes, \
> + .ncycles = __ncycles, \
> .buswidth = __buswidth, \

Please make sure this update and the drivers/spi/spi-mem.c driver
alterations are coherent with the SPI Nand driver. See the macro usages:
include/linux/mtd/spinand.h: SPINAND_PAGE_READ_FROM_*().

-Sergey

> }
>
> @@ -83,8 +83,8 @@ enum spi_mem_data_dir {
> * Note that only @addr.nbytes are taken into account in this
> * address value, so users should make sure the value fits in the
> * assigned number of bytes.
> - * @dummy.nbytes: number of dummy bytes to send after an opcode or address. Can
> - * be zero if the operation does not require dummy bytes
> + * @dummy.ncycles: number of dummy cycles after an opcode or address. Can
> + * be zero if the operation does not require dummy cycles
> * @dummy.buswidth: number of IO lanes used to transmit the dummy bytes
> * @dummy.dtr: whether the dummy bytes should be sent in DTR mode or not
> * @data.buswidth: number of IO lanes used to send/receive the data
> @@ -112,7 +112,7 @@ struct spi_mem_op {
> } addr;
>
> struct {
> - u8 nbytes;
> + u8 ncycles;
> u8 buswidth;
> u8 dtr : 1;
> } dummy;
> --
> 2.34.1