linux-kernel - [PATCH] spi: mediatek: Fix package division error

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Date:   Fri, 21 Oct 2022 17:16:53 +0800
From:   Zhichao Liu <zhichao.liu@...iatek.com>
To:     Mark Brown <broonie@...nel.org>
CC:     <linux-spi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <leilk.liu@...iatek.com>,
        <zhichao.liu@...iatek.com>
Subject: [PATCH] spi: mediatek: Fix package division error

From: "zhichao.liu" <zhichao.liu@...iatek.com>

Commit 7e963fb2a33ce ("spi: mediatek: add ipm design support
for MT7986") makes a mistake on package dividing operation
(one change is missing), need to fix it.

Background:
Ipm design is expanding the HW capability of dma (adjust package
length from 1KB to 64KB), and using "dev_comp->ipm_support" flag
to indicate it.

Issue description:
Ipm support patch (said above) is missing to handle remainder at
package dividing operation.
One case, a transmission length is 65KB, is will divide to 1K
(package length) * 65(package loop) in non-ipm desgin case, and
will divide to 64K(package length) * 1(package loop) + 1K(remainder)
in ipm design case. And the 1K remainder will be lost with the
current SW flow, and the transmission will be failure.
So, it should be fixed.

Solution:
Add "ipm_design" flag in function "mtk_spi_get_mult_delta()" to
indicate HW capability, and modify the parameters corespondingly.

fixes: 7e963fb2a33ce ("spi: mediatek: add ipm design support for MT7986")
Signed-off-by: zhichao.liu <zhichao.liu@...iatek.com>
---
 drivers/spi/spi-mt65xx.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 11aeae7fe7fc..a33c9a3de395 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -551,14 +551,17 @@ static void mtk_spi_enable_transfer(struct spi_master *master)
 	writel(cmd, mdata->base + SPI_CMD_REG);
 }
 
-static int mtk_spi_get_mult_delta(u32 xfer_len)
+static int mtk_spi_get_mult_delta(struct mtk_spi *mdata, u32 xfer_len)
 {
-	u32 mult_delta;
+	u32 mult_delta = 0;
 
-	if (xfer_len > MTK_SPI_PACKET_SIZE)
-		mult_delta = xfer_len % MTK_SPI_PACKET_SIZE;
-	else
-		mult_delta = 0;
+	if (mdata->dev_comp->ipm_design) {
+		if (xfer_len > MTK_SPI_IPM_PACKET_SIZE)
+			mult_delta = xfer_len % MTK_SPI_IPM_PACKET_SIZE;
+	} else {
+		if (xfer_len > MTK_SPI_PACKET_SIZE)
+			mult_delta = xfer_len % MTK_SPI_PACKET_SIZE;
+	}
 
 	return mult_delta;
 }
@@ -570,22 +573,22 @@ static void mtk_spi_update_mdata_len(struct spi_master *master)
 
 	if (mdata->tx_sgl_len && mdata->rx_sgl_len) {
 		if (mdata->tx_sgl_len > mdata->rx_sgl_len) {
-			mult_delta = mtk_spi_get_mult_delta(mdata->rx_sgl_len);
+			mult_delta = mtk_spi_get_mult_delta(mdata, mdata->rx_sgl_len);
 			mdata->xfer_len = mdata->rx_sgl_len - mult_delta;
 			mdata->rx_sgl_len = mult_delta;
 			mdata->tx_sgl_len -= mdata->xfer_len;
 		} else {
-			mult_delta = mtk_spi_get_mult_delta(mdata->tx_sgl_len);
+			mult_delta = mtk_spi_get_mult_delta(mdata, mdata->tx_sgl_len);
 			mdata->xfer_len = mdata->tx_sgl_len - mult_delta;
 			mdata->tx_sgl_len = mult_delta;
 			mdata->rx_sgl_len -= mdata->xfer_len;
 		}
 	} else if (mdata->tx_sgl_len) {
-		mult_delta = mtk_spi_get_mult_delta(mdata->tx_sgl_len);
+		mult_delta = mtk_spi_get_mult_delta(mdata, mdata->tx_sgl_len);
 		mdata->xfer_len = mdata->tx_sgl_len - mult_delta;
 		mdata->tx_sgl_len = mult_delta;
 	} else if (mdata->rx_sgl_len) {
-		mult_delta = mtk_spi_get_mult_delta(mdata->rx_sgl_len);
+		mult_delta = mtk_spi_get_mult_delta(mdata, mdata->rx_sgl_len);
 		mdata->xfer_len = mdata->rx_sgl_len - mult_delta;
 		mdata->rx_sgl_len = mult_delta;
 	}
-- 
2.18.0