i2c: brcmstb: Fix START and STOP conditions

The BSC data buffers to send and receive data are each of size 32 bytes
or 8 bytes 'xfersz' depending on SoC. The problem observed for all the
combined message transfer was if length of data transfer was a multiple
of 'xfersz' a repeated START was being transmitted by BSC driver. Fixed
this by appropriately setting START/STOP conditions for such transfers.

Fixes: dd1aa2524bc5 ("i2c: brcmstb: Add Broadcom settop SoC i2c controller driver")
Signed-off-by: Jaedon Shin <jaedon.shin@gmail.com>
Acked-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 21 insertions, 6 deletions

diff --git a/drivers/i2c/busses/i2c-brcmstb.c b/drivers/i2c/busses/i2c-brcmstb.c
index 0652281662a8..78792b4d6437 100644
--- a/drivers/i2c/busses/i2c-brcmstb.c
+++ b/drivers/i2c/busses/i2c-brcmstb.c
@@ -465,6 +465,7 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
         u8 *tmp_buf;
         int len = 0;
         int xfersz = brcmstb_i2c_get_xfersz(dev);
+        u32 cond, cond_per_msg;
 
         if (dev->is_suspended)
                 return -EBUSY;
@@ -481,10 +482,11 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
                         pmsg->buf ? pmsg->buf[0] : '0', pmsg->len);
 
                 if (i < (num - 1) && (msgs[i + 1].flags & I2C_M_NOSTART))
-                        brcmstb_set_i2c_start_stop(dev, ~(COND_START_STOP));
+                        cond = ~COND_START_STOP;
                 else
-                        brcmstb_set_i2c_start_stop(dev,
-                                                   COND_RESTART | COND_NOSTOP);
+                        cond = COND_RESTART | COND_NOSTOP;
+
+                brcmstb_set_i2c_start_stop(dev, cond);
 
                 /* Send slave address */
                 if (!(pmsg->flags & I2C_M_NOSTART)) {
@@ -497,13 +499,24 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
                         }
                 }
 
+                cond_per_msg = cond;
+
                 /* Perform data transfer */
                 while (len) {
                         bytes_to_xfer = min(len, xfersz);
 
-                        if (len <= xfersz && i == (num - 1))
-                                brcmstb_set_i2c_start_stop(dev,
-                                                           ~(COND_START_STOP));
+                        if (len <= xfersz) {
+                                if (i == (num - 1))
+                                        cond_per_msg = cond_per_msg &
+                                                ~(COND_RESTART | COND_NOSTOP);
+                                else
+                                        cond_per_msg = cond;
+                        } else {
+                                cond_per_msg = (cond_per_msg & ~COND_RESTART) |
+                                        COND_NOSTOP;
+                        }
+
+                        brcmstb_set_i2c_start_stop(dev, cond_per_msg);
 
                         rc = brcmstb_i2c_xfer_bsc_data(dev, tmp_buf,
                                                        bytes_to_xfer, pmsg);
@@ -512,6 +525,8 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
 
                         len -=  bytes_to_xfer;
                         tmp_buf += bytes_to_xfer;
+
+                        cond_per_msg = COND_NOSTART | COND_NOSTOP;
                 }
         }