Unverified Commit f8918ef1 authored by David Lechner's avatar David Lechner Committed by Mark Brown
Browse files

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: default avatarDavid Lechner <dlechner@baylibre.com>
Reviewed-by: default avatarNuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240723-spi-axi-spi-engine-opt-bpw-v1-1-2625ba4c4387@baylibre.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 8400291e

drivers/spi/spi-axi-spi-engine.c

+1 −1
Original line number Diff line number Diff line
@@ -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,