[PATCH RFT] spi: oc-tiny: Simplify tiny_spi_txrx_bufs implementation when irq is not used

[PATCH RFT] spi: oc-tiny: Simplify tiny_spi_txrx_bufs implementation when irq is not used

[Axel Lin]

Currently we have similar code for (txp && rxp), (txp && !rxp), (!rxp & txp),
and (!txp && !rxp) cases. This patch refactors the code a bit to avoid
duplicate similar code.

Signed-off-by: Axel Lin <axel.lin-8E1dMatC8ynQT0dZR+AlfA@public.gmane.org>
---
Hi Thomas,
I don't have this hardware, so please test this path if you think it is ok.
I think there is no functional change with this patch.

Thanks,
Axel
 drivers/spi/spi-oc-tiny.c | 62 +++++++++--------------------------------------
 1 file changed, 11 insertions(+), 51 deletions(-)

diff --git a/drivers/spi/spi-oc-tiny.c b/drivers/spi/spi-oc-tiny.c
index 91c6685..f7c896e 100644
--- a/drivers/spi/spi-oc-tiny.c
+++ b/drivers/spi/spi-oc-tiny.c
@@ -153,62 +153,22 @@ static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 		}
 
 		wait_for_completion(&hw->done);
-	} else if (txp && rxp) {
-		/* we need to tighten the transfer loop */
-		writeb(*txp++, hw->base + TINY_SPI_TXDATA);
-		if (t->len > 1) {
-			writeb(*txp++, hw->base + TINY_SPI_TXDATA);
-			for (i = 2; i < t->len; i++) {
-				u8 rx, tx = *txp++;
-				tiny_spi_wait_txr(hw);
-				rx = readb(hw->base + TINY_SPI_TXDATA);
-				writeb(tx, hw->base + TINY_SPI_TXDATA);
-				*rxp++ = rx;
-			}
-			tiny_spi_wait_txr(hw);
-			*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
-		}
-		tiny_spi_wait_txe(hw);
-		*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
-	} else if (rxp) {
-		writeb(0, hw->base + TINY_SPI_TXDATA);
-		if (t->len > 1) {
-			writeb(0,
-			       hw->base + TINY_SPI_TXDATA);
-			for (i = 2; i < t->len; i++) {
-				u8 rx;
-				tiny_spi_wait_txr(hw);
-				rx = readb(hw->base + TINY_SPI_TXDATA);
-				writeb(0, hw->base + TINY_SPI_TXDATA);
-				*rxp++ = rx;
-			}
-			tiny_spi_wait_txr(hw);
-			*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
-		}
-		tiny_spi_wait_txe(hw);
-		*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
-	} else if (txp) {
-		writeb(*txp++, hw->base + TINY_SPI_TXDATA);
-		if (t->len > 1) {
-			writeb(*txp++, hw->base + TINY_SPI_TXDATA);
-			for (i = 2; i < t->len; i++) {
-				u8 tx = *txp++;
-				tiny_spi_wait_txr(hw);
-				writeb(tx, hw->base + TINY_SPI_TXDATA);
-			}
-		}
-		tiny_spi_wait_txe(hw);
 	} else {
-		writeb(0, hw->base + TINY_SPI_TXDATA);
-		if (t->len > 1) {
-			writeb(0, hw->base + TINY_SPI_TXDATA);
-			for (i = 2; i < t->len; i++) {
+		/* we need to tighten the transfer loop */
+		writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
+		for (i = 1; i < t->len; i++) {
+			writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
+
+			if (rxp || (i != t->len - 1))
 				tiny_spi_wait_txr(hw);
-				writeb(0, hw->base + TINY_SPI_TXDATA);
-			}
+			if (rxp)
+				*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
 		}
 		tiny_spi_wait_txe(hw);
+		if (rxp)
+			*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
 	}
+
 	return t->len;
 }
 
-- 
1.8.1.2



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Re: [PATCH RFT] spi: oc-tiny: Simplify tiny_spi_txrx_bufs implementation when irq is not used

[Mark Brown]

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On Wed, Jan 08, 2014 at 04:00:04PM +0800, Axel Lin wrote:
> Currently we have similar code for (txp && rxp), (txp && !rxp), (!rxp & txp),
> and (!txp && !rxp) cases. This patch refactors the code a bit to avoid
> duplicate similar code.

Applied, thanks - it's actually a moderately common pattern in various
ways in drivers.  I was thinking it might be good to have the core
provide dummy buffers to drivers that need to do bidirectional transfers
so the drivers only need to set a flag and don't need to open code this.

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