To do so, spi communication can use an empty buf to pull up CS.
This patch merged from ChromiumOS tree.
Cros_ec use this function to turn off CS and add a delay to ensure
the rising edge doesn't come too soon after the end of the data.
Tested-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Addy Ke <addy.ke@xxxxxxxxxxxxxx>
---
drivers/spi/spi-rockchip.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 72fb287..1e3bcfa 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -511,8 +511,8 @@ static int rockchip_spi_transfer_one(struct spi_master *master,
WARN_ON((readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY));
if (!xfer->tx_buf && !xfer->rx_buf) {
- dev_err(rs->dev, "No buffer for transfer\n");
- return -EINVAL;
+ dev_dbg(rs->dev, "No buffer for transfer\n");
+ return 0;
}
rs->speed = xfer->speed_hz;
--
1.8.3.2
--
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