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From: Jaewon Kim <jaewon02.kim@samsung.com>
To: Andi Shyti <andi.shyti@kernel.org>, Mark Brown <broonie@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>, Alim Akhtar
	<alim.akhtar@samsung.com>
Cc: linux-spi@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jaewon
	Kim <jaewon02.kim@samsung.com>
Subject: [PATCH] spi: s3c64xx: Use DMA mode from fifo size
Date: Wed, 27 Mar 2024 12:30:41 +0900
Message-ID: <20240327033041.83625-1-jaewon02.kim@samsung.com>
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References: <CGME20240327033501epcas2p2bbe21301da5584f7f3a073c51a363c00@epcas2p2.samsung.com>

The SPI data size is smaller than FIFO, it operates in PIO mode,
and if it is larger than FIFO mode, DMA mode is selected.

If the data size is the same as the FIFO size, it operates in PIO mode
and data is separated into two transfer. In order to prevent,
DMA mode must be used from the case of FIFO and data size.

Fixes: 1ee806718d5e ("spi: s3c64xx: support interrupt based pio mode")
Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
---
 drivers/spi/spi-s3c64xx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 9fcbe040cb2f..81ed5fddf83e 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -430,7 +430,7 @@ static bool s3c64xx_spi_can_dma(struct spi_controller *host,
 	struct s3c64xx_spi_driver_data *sdd = spi_controller_get_devdata(host);
 
 	if (sdd->rx_dma.ch && sdd->tx_dma.ch)
-		return xfer->len > sdd->fifo_depth;
+		return xfer->len >= sdd->fifo_depth;
 
 	return false;
 }
@@ -826,11 +826,11 @@ static int s3c64xx_spi_transfer_one(struct spi_controller *host,
 			return status;
 	}
 
-	if (!is_polling(sdd) && (xfer->len > fifo_len) &&
+	if (!is_polling(sdd) && xfer->len >= fifo_len &&
 	    sdd->rx_dma.ch && sdd->tx_dma.ch) {
 		use_dma = 1;
 
-	} else if (xfer->len >= fifo_len) {
+	} else if (xfer->len > fifo_len) {
 		tx_buf = xfer->tx_buf;
 		rx_buf = xfer->rx_buf;
 		origin_len = xfer->len;
-- 
2.43.2