diff options
Diffstat (limited to 'drivers/spi/spi-axi-spi-engine.c')
| -rw-r--r-- | drivers/spi/spi-axi-spi-engine.c | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c index e358ac5b45..96a5247725 100644 --- a/drivers/spi/spi-axi-spi-engine.c +++ b/drivers/spi/spi-axi-spi-engine.c @@ -164,16 +164,20 @@ static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry, } static void spi_engine_gen_sleep(struct spi_engine_program *p, bool dry, - int delay_ns, u32 sclk_hz) + int delay_ns, int inst_ns, u32 sclk_hz) { unsigned int t; - /* negative delay indicates error, e.g. from spi_delay_to_ns() */ - if (delay_ns <= 0) + /* + * Negative delay indicates error, e.g. from spi_delay_to_ns(). And if + * delay is less that the instruction execution time, there is no need + * for an extra sleep instruction since the instruction execution time + * will already cover the required delay. + */ + if (delay_ns < 0 || delay_ns <= inst_ns) return; - /* rounding down since executing the instruction adds a couple of ticks delay */ - t = DIV_ROUND_DOWN_ULL((u64)delay_ns * sclk_hz, NSEC_PER_SEC); + t = DIV_ROUND_UP_ULL((u64)(delay_ns - inst_ns) * sclk_hz, NSEC_PER_SEC); while (t) { unsigned int n = min(t, 256U); @@ -220,10 +224,16 @@ static void spi_engine_compile_message(struct spi_message *msg, bool dry, struct spi_device *spi = msg->spi; struct spi_controller *host = spi->controller; struct spi_transfer *xfer; - int clk_div, new_clk_div; + int clk_div, new_clk_div, inst_ns; bool keep_cs = false; u8 bits_per_word = 0; + /* + * Take into account instruction execution time for more accurate sleep + * times, especially when the delay is small. + */ + inst_ns = DIV_ROUND_UP(NSEC_PER_SEC, host->max_speed_hz); + clk_div = 1; spi_engine_program_add_cmd(p, dry, @@ -252,7 +262,7 @@ static void spi_engine_compile_message(struct spi_message *msg, bool dry, spi_engine_gen_xfer(p, dry, xfer); spi_engine_gen_sleep(p, dry, spi_delay_to_ns(&xfer->delay, xfer), - xfer->effective_speed_hz); + inst_ns, xfer->effective_speed_hz); if (xfer->cs_change) { if (list_is_last(&xfer->transfer_list, &msg->transfers)) { @@ -262,7 +272,7 @@ static void spi_engine_compile_message(struct spi_message *msg, bool dry, spi_engine_gen_cs(p, dry, spi, false); spi_engine_gen_sleep(p, dry, spi_delay_to_ns( - &xfer->cs_change_delay, xfer), + &xfer->cs_change_delay, xfer), inst_ns, xfer->effective_speed_hz); if (!list_next_entry(xfer, transfer_list)->cs_off) |