drm/tinydrm: Clean up tinydrm_spi_transfer()

Prep work before moving the function to mipi-dbi.

tinydrm_spi_transfer() was made to support one class of drivers in
drivers/staging/fbtft that has not been converted to DRM yet, so strip
away the unused functionality:
- Start byte (header) is not used.
- No driver relies on the automatic 16-bit byte swapping on little endian
  machines with SPI controllers only supporting 8 bits per word.

Other changes:
- No need to initialize ret
- No need for the WARN since mipi-dbi only uses 8 and 16 bpw.
- Use spi_message_init_with_transfers()

Cc: David Lechner <david@lechnology.com>
Acked-by: : David Lechner <david@lechnology.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190719155916.62465-7-noralf@tronnes.org

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index ae31a5c9aa1b..8fb6ce4ca6fc 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -926,7 +926,7 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 *cmd,
 
 	gpiod_set_value_cansleep(mipi->dc, 0);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
-	ret = tinydrm_spi_transfer(spi, speed_hz, NULL, 8, cmd, 1);
+	ret = tinydrm_spi_transfer(spi, speed_hz, 8, cmd, 1);
 	if (ret || !num)
 		return ret;
 
@@ -936,7 +936,7 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 *cmd,
 	gpiod_set_value_cansleep(mipi->dc, 1);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
 
-	return tinydrm_spi_transfer(spi, speed_hz, NULL, bpw, par, num);
+	return tinydrm_spi_transfer(spi, speed_hz, bpw, par, num);
 }
 
 /**