Merge tag 'i2c-fixes-7.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux

Pull i2c fixes from Andi Shyti:
 "Three patches in xiic for fixing the block reads and a single cleanup
  in the at91 error path:

   - at91: also release DMA channels when deferring probe

   - xiic: fix SMBus block reads with PEC"

* tag 'i2c-fixes-7.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux:
  i2c: at91: release DMA channels when probe defers
  i2c: xiic: don't clobber msg->len to signal block-read completion
  i2c: xiic: defer RX_FULL until all trailing bytes are in FIFO
  i2c: xiic: preserve PEC byte length in SMBus block read setup

2 files changed, 53 insertions, 16 deletions

diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
index 68238cc8a..e0c3de5e8 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -921,8 +921,14 @@ int at91_twi_probe_master(struct platform_device *pdev,
 	at91_calc_twi_clock(dev);
 
 	rc = at91_init_twi_recovery_info(pdev, dev);
-	if (rc == -EPROBE_DEFER)
+	if (rc == -EPROBE_DEFER) {
+		/*
+		 * The DMA channels were already set up above, release them
+		 * before deferring the probe so they are not leaked.
+		 */
+		at91_twi_dma_release(dev);
 		return rc;
+	}
 
 	dev->adapter.algo = &at91_twi_algorithm;
 	dev->adapter.quirks = &at91_twi_quirks;
diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index 3e7735e1d..5e397a7e6 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -73,6 +73,9 @@ enum i2c_scl_freq {
  * @prev_msg_tx: Previous message is Tx
  * @quirks: To hold platform specific bug info
  * @smbus_block_read: Flag to handle block read
+ * @smbus_actual_len: Valid byte count (length + payload + optional PEC) of a
+ *	padded SMBus block read. msg->len is trimmed to this on completion.
+ *	Zero when no trimming is needed.
  * @input_clk: Input clock to I2C controller
  * @i2c_clk: I2C SCL frequency
  * @atomic: Mode of transfer
@@ -98,6 +101,7 @@ struct xiic_i2c {
 	bool prev_msg_tx;
 	u32 quirks;
 	bool smbus_block_read;
+	unsigned int smbus_actual_len;
 	unsigned long input_clk;
 	unsigned int i2c_clk;
 	bool atomic;
@@ -539,30 +543,38 @@ static void xiic_smbus_block_read_setup(struct xiic_i2c *i2c)
 
 	/* Check if received length is valid */
 	if (rxmsg_len <= I2C_SMBUS_BLOCK_MAX) {
+		unsigned int pec_len = i2c->rx_msg->len - 1;
+
 		/* Set Receive fifo depth */
-		if (rxmsg_len > IIC_RX_FIFO_DEPTH) {
+		if (rxmsg_len + pec_len > IIC_RX_FIFO_DEPTH) {
 			/*
-			 * When Rx msg len greater than or equal to Rx fifo capacity
-			 * Receive fifo depth should set to Rx fifo capacity minus 1
+			 * Trailing bytes (payload plus any PEC) exceed Rx FIFO
+			 * capacity, so drain in chunks. This also keeps the
+			 * else branch below from pushing rfd_set past the
+			 * 4-bit XIIC_RFD_REG_OFFSET field.
 			 */
 			rfd_set = IIC_RX_FIFO_DEPTH - 1;
-			i2c->rx_msg->len = rxmsg_len + 1;
-		} else if ((rxmsg_len == 1) ||
-			(rxmsg_len == 0)) {
+			i2c->rx_msg->len = rxmsg_len + 1 + pec_len;
+		} else if (1 + rxmsg_len + pec_len < SMBUS_BLOCK_READ_MIN_LEN) {
 			/*
-			 * Minimum of 3 bytes required to exit cleanly. 1 byte
-			 * already received, Second byte is being received. Have
-			 * to set NACK in read_rx before receiving the last byte
+			 * The HW needs SMBUS_BLOCK_READ_MIN_LEN bytes on the
+			 * bus to exit cleanly: by the time the ISR reads the
+			 * length byte the second byte is already being clocked
+			 * in, too late to NACK. Pad the drain target and record
+			 * the real length, trimmed back on completion so the
+			 * PEC check sees the right byte.
 			 */
 			rfd_set = 0;
 			i2c->rx_msg->len = SMBUS_BLOCK_READ_MIN_LEN;
+			i2c->smbus_actual_len = 1 + rxmsg_len + pec_len;
 		} else {
 			/*
-			 * When Rx msg len less than Rx fifo capacity
-			 * Receive fifo depth should set to Rx msg len minus 2
+			 * All trailing bytes fit in the Rx FIFO. Defer RX_FULL
+			 * until every one of them is buffered, so the drain
+			 * takes xiic_read_rx()'s bytes_rem == 0 path.
 			 */
-			rfd_set = rxmsg_len - 2;
-			i2c->rx_msg->len = rxmsg_len + 1;
+			rfd_set = rxmsg_len + pec_len - 1;
+			i2c->rx_msg->len = rxmsg_len + 1 + pec_len;
 		}
 		xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, rfd_set);
 
@@ -575,6 +587,16 @@ static void xiic_smbus_block_read_setup(struct xiic_i2c *i2c)
 	dev_err(i2c->adap.dev.parent, "smbus_block_read Invalid msg length\n");
 }
 
+/*
+ * Undo the setup-time padding of a short SMBus block read before rx_msg is
+ * cleared, so the PEC check sees the right byte.
+ */
+static void xiic_smbus_trim_len(struct xiic_i2c *i2c)
+{
+	if (i2c->rx_msg && i2c->smbus_actual_len)
+		i2c->rx_msg->len = i2c->smbus_actual_len;
+}
+
 static void xiic_read_rx(struct xiic_i2c *i2c)
 {
 	u8 bytes_in_fifo, cr = 0, bytes_to_read = 0;
@@ -797,6 +819,8 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 
 		xiic_read_rx(i2c);
 		if (xiic_rx_space(i2c) == 0) {
+			xiic_smbus_trim_len(i2c);
+
 			/* this is the last part of the message */
 			i2c->rx_msg = NULL;
 
@@ -865,8 +889,11 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 
 		if (i2c->tx_msg && i2c->smbus_block_read) {
 			i2c->smbus_block_read = false;
-			/* Set requested message len=1 to indicate STATE_DONE */
-			i2c->tx_msg->len = 1;
+			/*
+			 * Drive xiic_tx_space() to 0 to signal STATE_DONE
+			 * without truncating the rx_msg length.
+			 */
+			i2c->tx_pos = i2c->tx_msg->len;
 		}
 
 		if (!i2c->tx_msg)
@@ -938,6 +965,7 @@ static void xiic_recv_atomic(struct xiic_i2c *i2c)
 			return;
 	}
 
+	xiic_smbus_trim_len(i2c);
 	i2c->rx_msg = NULL;
 	xiic_irq_clr_en(i2c, XIIC_INTR_TX_ERROR_MASK);
 
@@ -955,6 +983,9 @@ static void xiic_start_recv(struct xiic_i2c *i2c)
 	u8 cr = 0, rfd_set = 0;
 	struct i2c_msg *msg = i2c->rx_msg = i2c->tx_msg;
 
+	/* A stale value from an aborted block read would truncate this msg. */
+	i2c->smbus_actual_len = 0;
+
 	if (!i2c->atomic)
 		dev_dbg(i2c->adap.dev.parent, "%s entry, ISR: 0x%x, CR: 0x%x\n",
 			__func__, xiic_getreg32(i2c, XIIC_IISR_OFFSET),