linux-kernel - [PATCH v5 18/36] i2c: tegra: Don't fall back to PIO mode if DMA configuration fails

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Message-Id: <20200906185039.22700-19-digetx@gmail.com>
Date:   Sun,  6 Sep 2020 21:50:21 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v5 18/36] i2c: tegra: Don't fall back to PIO mode if DMA configuration fails

The DMA code path has been tested well enough and the DMA configuration
performed by tegra_i2c_config_fifo_trig() shouldn't ever fail in practice.
Hence let's remove the obscure transfer-mode switching in order to have a
cleaner and simpler code. Now I2C transfer will be failed if DMA
configuration fails.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/i2c/busses/i2c-tegra.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 20168e49dbb2..f38e0f3fe367 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -975,8 +975,7 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev,
-				       size_t len)
+static int tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev, size_t len)
 {
 	u32 val, reg;
 	u8 dma_burst;
@@ -1027,12 +1026,10 @@ static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev,
 		if (ret < 0) {
 			dev_err(i2c_dev->dev, "DMA slave config failed: %d\n",
 				ret);
-			dev_err(i2c_dev->dev, "falling back to PIO\n");
-			tegra_i2c_release_dma(i2c_dev);
-			i2c_dev->is_curr_dma_xfer = false;
-		} else {
-			goto out;
+			return ret;
 		}
+
+		goto out;
 	}
 
 	if (i2c_dev->hw->has_mst_fifo)
@@ -1043,6 +1040,8 @@ static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev,
 		      I2C_FIFO_CONTROL_RX_TRIG(1);
 out:
 	i2c_writel(i2c_dev, val, reg);
+
+	return 0;
 }
 
 static unsigned long
@@ -1176,7 +1175,10 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
 	i2c_dev->is_curr_dma_xfer = (xfer_size > I2C_PIO_MODE_PREFERRED_LEN) &&
 				    i2c_dev->dma_buf &&
 				    !i2c_dev->is_curr_atomic_xfer;
-	tegra_i2c_config_fifo_trig(i2c_dev, xfer_size);
+
+	err = tegra_i2c_config_fifo_trig(i2c_dev, xfer_size);
+	if (err)
+		return err;
 
 	/*
 	 * Transfer time in mSec = Total bits / transfer rate
-- 
2.27.0