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>

diff --git a/drivers/i2c/busses/i2c-brcmstb.c b/drivers/i2c/busses/i2c-brcmstb.c
index 0652281662a8b35b974d084c5d0636f8ac75e450..78792b4d6437c7cca6d84fd4977773f0c65781e2 100644 (file)
--- 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;
                }
        }