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SubjectRe: [PATCH v3 3/3] spi: s3c64xx: support interrupt based pio mode
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On 02/05/2023 08:28, Jaewon Kim wrote:
> Support interrupt based pio mode to optimize cpu usage.
> When transmitting data size is larget than 32 bytes, operates with
> interrupt based pio mode.
>
> By using the FIFORDY INT, an interrupt can be triggered when
> the desired size of data has been received. Using this, we can support
> interrupt based pio mode.
>
> Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
> ---
> drivers/spi/spi-s3c64xx.c | 66 ++++++++++++++++++++++++++++++++++-----
> 1 file changed, 58 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
> index 2a8304678df9..323c6da9730b 100644
> --- a/drivers/spi/spi-s3c64xx.c
> +++ b/drivers/spi/spi-s3c64xx.c
> @@ -58,6 +58,8 @@
> #define S3C64XX_SPI_MODE_BUS_TSZ_HALFWORD (1<<17)
> #define S3C64XX_SPI_MODE_BUS_TSZ_WORD (2<<17)
> #define S3C64XX_SPI_MODE_BUS_TSZ_MASK (3<<17)
> +#define S3C64XX_SPI_MODE_RX_RDY_LVL GENMASK(16, 11)
> +#define S3C64XX_SPI_MODE_RX_RDY_LVL_SHIFT 11
> #define S3C64XX_SPI_MODE_SELF_LOOPBACK (1<<3)
> #define S3C64XX_SPI_MODE_RXDMA_ON (1<<2)
> #define S3C64XX_SPI_MODE_TXDMA_ON (1<<1)
> @@ -114,6 +116,8 @@
>
> #define S3C64XX_SPI_TRAILCNT S3C64XX_SPI_MAX_TRAILCNT
>
> +#define S3C64XX_SPI_POLLING_SIZE 32
> +
> #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
> #define is_polling(x) (x->cntrlr_info->polling)
>
> @@ -552,7 +556,7 @@ static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd,
> }
>
> static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
> - struct spi_transfer *xfer)
> + struct spi_transfer *xfer, bool use_irq)
> {
> void __iomem *regs = sdd->regs;
> unsigned long val;
> @@ -573,6 +577,12 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
> if (RX_FIFO_LVL(status, sdd) < xfer->len)
> usleep_range(time_us / 2, time_us);
>
> + if (use_irq) {
> + val = msecs_to_jiffies(ms);
> + if (!wait_for_completion_timeout(&sdd->xfer_completion, val))
> + return -EIO;
> + }
> +
> val = msecs_to_loops(ms);
> do {
> status = readl(regs + S3C64XX_SPI_STATUS);
> @@ -735,10 +745,13 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
> void *rx_buf = NULL;
> int target_len = 0, origin_len = 0;
> int use_dma = 0;
> + bool use_irq = false;
> int status;
> u32 speed;
> u8 bpw;
> unsigned long flags;
> + u32 rdy_lv;
> + u32 val;
>
> reinit_completion(&sdd->xfer_completion);
>
> @@ -759,17 +772,46 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
> sdd->rx_dma.ch && sdd->tx_dma.ch) {
> use_dma = 1;
>
> - } else if (xfer->len > fifo_len) {
> + } else if (xfer->len >= fifo_len) {

I don't fully understand this. If len equals to fifo_len, everything
would fit into FIFO so no need for all this?

> tx_buf = xfer->tx_buf;
> rx_buf = xfer->rx_buf;
> origin_len = xfer->len;
> -
> target_len = xfer->len;
> - if (xfer->len > fifo_len)
> - xfer->len = fifo_len;
> + xfer->len = fifo_len - 1;
> }
>
> do {
> + /* transfer size is greater than 32, change to IRQ mode */
> + if (xfer->len > S3C64XX_SPI_POLLING_SIZE)
> + use_irq = true;
> +
> + if (use_irq) {
> + reinit_completion(&sdd->xfer_completion);
> +
> + rdy_lv = xfer->len;

Style is:

/*
*

> + /* Setup RDY_FIFO trigger Level
> + * RDY_LVL =
> + * fifo_lvl up to 64 byte -> N bytes
> + * 128 byte -> RDY_LVL * 2 bytes
> + * 256 byte -> RDY_LVL * 4 bytes

I don't understand it. Based on this equation for 256 bytes,
RDY_LVL = RDY_LVL * 4?
Didn't you mean xfer->len?


Best regards,
Krzysztof

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