6 files changed, 29 insertions, 16 deletions

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index ead5e7de3e4d..416f89b8f881 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -86,7 +86,6 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev)
         struct i2c_timings *t = &dev->timings;
         u32 ss_ht = 0, fp_ht = 0, hs_ht = 0, fs_ht = 0;
 
-        dev->adapter.nr = -1;
         dev->tx_fifo_depth = 32;
         dev->rx_fifo_depth = 32;
 
@@ -219,7 +218,7 @@ static void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
         dev->mode = DW_IC_SLAVE;
 }
 
-static void dw_i2c_set_fifo_size(struct dw_i2c_dev *dev, int id)
+static void dw_i2c_set_fifo_size(struct dw_i2c_dev *dev)
 {
         u32 param, tx_fifo_depth, rx_fifo_depth;
 
@@ -233,7 +232,6 @@ static void dw_i2c_set_fifo_size(struct dw_i2c_dev *dev, int id)
         if (!dev->tx_fifo_depth) {
                 dev->tx_fifo_depth = tx_fifo_depth;
                 dev->rx_fifo_depth = rx_fifo_depth;
-                dev->adapter.nr = id;
         } else if (tx_fifo_depth >= 2) {
                 dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
                                 tx_fifo_depth);
@@ -358,13 +356,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
                                 div_u64(clk_khz * t->sda_hold_ns + 500000, 1000000);
         }
 
-        dw_i2c_set_fifo_size(dev, pdev->id);
+        dw_i2c_set_fifo_size(dev);
 
         adap = &dev->adapter;
         adap->owner = THIS_MODULE;
         adap->class = I2C_CLASS_DEPRECATED;
         ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
         adap->dev.of_node = pdev->dev.of_node;
+        adap->nr = -1;
 
         dev_pm_set_driver_flags(&pdev->dev,
                                 DPM_FLAG_SMART_PREPARE |
diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 660de1ee68ed..684d651612b3 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -503,7 +503,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
                 writel(I2C_DMA_INT_FLAG_NONE, i2c->pdmabase + OFFSET_INT_FLAG);
                 writel(I2C_DMA_CON_RX, i2c->pdmabase + OFFSET_CON);
 
-                dma_rd_buf = i2c_get_dma_safe_msg_buf(msgs, 0);
+                dma_rd_buf = i2c_get_dma_safe_msg_buf(msgs, 1);
                 if (!dma_rd_buf)
                         return -ENOMEM;
 
@@ -526,7 +526,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
                 writel(I2C_DMA_INT_FLAG_NONE, i2c->pdmabase + OFFSET_INT_FLAG);
                 writel(I2C_DMA_CON_TX, i2c->pdmabase + OFFSET_CON);
 
-                dma_wr_buf = i2c_get_dma_safe_msg_buf(msgs, 0);
+                dma_wr_buf = i2c_get_dma_safe_msg_buf(msgs, 1);
                 if (!dma_wr_buf)
                         return -ENOMEM;
 
@@ -549,7 +549,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
                 writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_INT_FLAG);
                 writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_CON);
 
-                dma_wr_buf = i2c_get_dma_safe_msg_buf(msgs, 0);
+                dma_wr_buf = i2c_get_dma_safe_msg_buf(msgs, 1);
                 if (!dma_wr_buf)
                         return -ENOMEM;
 
@@ -561,7 +561,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
                         return -ENOMEM;
                 }
 
-                dma_rd_buf = i2c_get_dma_safe_msg_buf((msgs + 1), 0);
+                dma_rd_buf = i2c_get_dma_safe_msg_buf((msgs + 1), 1);
                 if (!dma_rd_buf) {
                         dma_unmap_single(i2c->dev, wpaddr,
                                          msgs->len, DMA_TO_DEVICE);
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index dd52a068b140..a7578f6da979 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -363,9 +363,6 @@ static void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv)
         struct dma_chan *chan = priv->dma_direction == DMA_FROM_DEVICE
                 ? priv->dma_rx : priv->dma_tx;
 
-        /* Disable DMA Master Received/Transmitted */
-        rcar_i2c_write(priv, ICDMAER, 0);
-
         dma_unmap_single(chan->device->dev, sg_dma_address(&priv->sg),
                          sg_dma_len(&priv->sg), priv->dma_direction);
 
@@ -375,6 +372,9 @@ static void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv)
                 priv->flags |= ID_P_NO_RXDMA;
 
         priv->dma_direction = DMA_NONE;
+
+        /* Disable DMA Master Received/Transmitted, must be last! */
+        rcar_i2c_write(priv, ICDMAER, 0);
 }
 
 static void rcar_i2c_cleanup_dma(struct rcar_i2c_priv *priv)
@@ -611,6 +611,15 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
         return true;
 }
 
+/*
+ * This driver has a lock-free design because there are IP cores (at least
+ * R-Car Gen2) which have an inherent race condition in their hardware design.
+ * There, we need to clear RCAR_BUS_MASK_DATA bits as soon as possible after
+ * the interrupt was generated, otherwise an unwanted repeated message gets
+ * generated. It turned out that taking a spinlock at the beginning of the ISR
+ * was already causing repeated messages. Thus, this driver was converted to
+ * the now lockless behaviour. Please keep this in mind when hacking the driver.
+ */
 static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
 {
         struct rcar_i2c_priv *priv = ptr;
diff --git a/drivers/i2c/busses/i2c-sis630.c b/drivers/i2c/busses/i2c-sis630.c
index 1e6805b5cef2..a57aa4fe51a4 100644
--- a/drivers/i2c/busses/i2c-sis630.c
+++ b/drivers/i2c/busses/i2c-sis630.c
@@ -478,7 +478,7 @@ static int sis630_setup(struct pci_dev *sis630_dev)
         if (!request_region(smbus_base + SMB_STS, SIS630_SMB_IOREGION,
                             sis630_driver.name)) {
                 dev_err(&sis630_dev->dev,
-                        "I/O Region 0x%04hx-0x%04hx for SMBus already in use.\n",
+                        "I/O Region 0x%04x-0x%04x for SMBus already in use.\n",
                         smbus_base + SMB_STS,
                         smbus_base + SMB_STS + SIS630_SMB_IOREGION - 1);
                 retval = -EBUSY;
@@ -528,7 +528,7 @@ static int sis630_probe(struct pci_dev *dev, const struct pci_device_id *id)
         sis630_adapter.dev.parent = &dev->dev;
 
         snprintf(sis630_adapter.name, sizeof(sis630_adapter.name),
-                 "SMBus SIS630 adapter at %04hx", smbus_base + SMB_STS);
+                 "SMBus SIS630 adapter at %04x", smbus_base + SMB_STS);
 
         return i2c_add_adapter(&sis630_adapter);
 }
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 13e1213561d4..4284fc991cfd 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -432,7 +432,7 @@ static int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
                  STM32F7_I2C_ANALOG_FILTER_DELAY_MAX : 0);
         dnf_delay = setup->dnf * i2cclk;
 
-        sdadel_min = setup->fall_time - i2c_specs[setup->speed].hddat_min -
+        sdadel_min = i2c_specs[setup->speed].hddat_min + setup->fall_time -
                 af_delay_min - (setup->dnf + 3) * i2cclk;
 
         sdadel_max = i2c_specs[setup->speed].vddat_max - setup->rise_time -
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index cb6c5cb0df0b..38af18645133 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -2258,7 +2258,8 @@ EXPORT_SYMBOL(i2c_put_adapter);
 /**
  * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
  * @msg: the message to be checked
- * @threshold: the minimum number of bytes for which using DMA makes sense
+ * @threshold: the minimum number of bytes for which using DMA makes sense.
+ *             Should at least be 1.
  *
  * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
  *         Or a valid pointer to be used with DMA. After use, release it by
@@ -2268,7 +2269,11 @@ EXPORT_SYMBOL(i2c_put_adapter);
  */
 u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)
 {
-        if (msg->len < threshold)
+        /* also skip 0-length msgs for bogus thresholds of 0 */
+        if (!threshold)
+                pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
+                         msg->addr);
+        if (msg->len < threshold || msg->len == 0)
                 return NULL;
 
         if (msg->flags & I2C_M_DMA_SAFE)