spi: spi-sun6i: sun6i_spi_drain_fifo(): remove not needed length argument

The function sun6i_spi_drain_fifo() is called with a length argument of
"sspi->fifo_depth" and "SUN6I_FIFO_DEPTH".

The driver reads the number of available bytes to read from the FIFO from the
hardware and uses the length argument to limit this value. This is not needed
as the FIFO can contain only the fifo depth number of bytes.

This patch removes the length argument and check.
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20200706143443.9855-8-mkl@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-sun6i.c

@@ -135,16 +135,13 @@ static inline void sun6i_spi_disable_interrupt(struct sun6i_spi *sspi, u32 mask)
 	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, reg);
 }
 
-static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
+static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi)
 {
-	u32 cnt;
+	u32 len;
 	u8 byte;
 
 	/* See how much data is available */
-	cnt = sun6i_spi_get_rx_fifo_count(sspi);
-
-	if (len > cnt)
-		len = cnt;
+	len = sun6i_spi_get_rx_fifo_count(sspi);
 
 	while (len--) {
 		byte = readb(sspi->base_addr + SUN6I_RXDATA_REG);
@@ -348,14 +345,14 @@ static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
 	/* Transfer complete */
 	if (status & SUN6I_INT_CTL_TC) {
 		sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
-		sun6i_spi_drain_fifo(sspi, sspi->fifo_depth);
+		sun6i_spi_drain_fifo(sspi);
 		complete(&sspi->done);
 		return IRQ_HANDLED;
 	}
 
 	/* Receive FIFO 3/4 full */
 	if (status & SUN6I_INT_CTL_RF_RDY) {
-		sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
+		sun6i_spi_drain_fifo(sspi);
 		/* Only clear the interrupt _after_ draining the FIFO */
 		sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_RF_RDY);
 		return IRQ_HANDLED;