From f8918ef1267edab4d9b2154c22a912c87cc66f66 Mon Sep 17 00:00:00 2001 From: David Lechner Date: Tue, 23 Jul 2024 13:36:47 -0500 Subject: [PATCH] spi: axi-spi-engine: don't emit XFER_BITS for empty xfer This adds a check on xfer->len to avoid emitting an XFER_BITS instruction for empty transfers in the AXI SPI Engine driver. This avoids unnecessary delays caused by executing an instruction that has no effect on the actual SPI transfer. Signed-off-by: David Lechner Reviewed-by: Nuno Sa Link: https://patch.msgid.link/20240723-spi-axi-spi-engine-opt-bpw-v1-1-2625ba4c4387@baylibre.com Signed-off-by: Mark Brown --- drivers/spi/spi-axi-spi-engine.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c index 447e5a962dee..cb3fdcbca2be 100644 --- a/drivers/spi/spi-axi-spi-engine.c +++ b/drivers/spi/spi-axi-spi-engine.c @@ -258,7 +258,7 @@ static void spi_engine_compile_message(struct spi_message *msg, bool dry, clk_div - 1)); } - if (bits_per_word != xfer->bits_per_word) { + if (bits_per_word != xfer->bits_per_word && xfer->len) { bits_per_word = xfer->bits_per_word; spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_XFER_BITS, -- 2.50.1