Revert "i2c: designware: detect when dynamic tar update is possible"

commit 12688dc upstream.

This reverts commit 63d0f0a.

It caused a regression on platforms where I2C controller is synthesized
with dynamic TAR update disabled. Detection code is testing is bit
DW_IC_CON_10BITADDR_MASTER in register DW_IC_CON read-only but fails to
restore original value in case bit is read-write.

Instead of fixing this we revert the commit since it was preparation for
the commit 0317e6c ("i2c: designware: do not disable adapter after
transfer") which was also reverted.

Reported-by: Shah Nehal-Bakulchandra <[email protected]>
Reported-by: Suravee Suthikulpanit <[email protected]>
Acked-By: Lucas De Marchi <[email protected]>
Fixes: 63d0f0a ("i2c: designware: detect when dynamic tar update is possible")
Signed-off-by: Jarkko Nikula <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/i2c/busses/i2c-designware-core.c

@@ -475,30 +475,28 @@ static int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
 static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 {
  struct i2c_msg *msgs = dev->msgs;
- u32 ic_tar = 0;
+ u32 ic_con, ic_tar = 0;
 
  /* Disable the adapter */
  __i2c_dw_enable_and_wait(dev, false);
 
  /* if the slave address is ten bit address, enable 10BITADDR */
- if (dev->dynamic_tar_update_enabled) {
+ ic_con = dw_readl(dev, DW_IC_CON);
+ if (msgs[dev->msg_write_idx].flags & I2C_M_TEN) {
+ ic_con |= DW_IC_CON_10BITADDR_MASTER;
  /*
  * If I2C_DYNAMIC_TAR_UPDATE is set, the 10-bit addressing
- * mode has to be enabled via bit 12 of IC_TAR register,
- * otherwise bit 4 of IC_CON is used.
+ * mode has to be enabled via bit 12 of IC_TAR register.
+ * We set it always as I2C_DYNAMIC_TAR_UPDATE can't be
+ * detected from registers.
  */
- if (msgs[dev->msg_write_idx].flags & I2C_M_TEN)
- ic_tar = DW_IC_TAR_10BITADDR_MASTER;
+ ic_tar = DW_IC_TAR_10BITADDR_MASTER;
  } else {
- u32 ic_con = dw_readl(dev, DW_IC_CON);
-
- if (msgs[dev->msg_write_idx].flags & I2C_M_TEN)
- ic_con |= DW_IC_CON_10BITADDR_MASTER;
- else
- ic_con &= ~DW_IC_CON_10BITADDR_MASTER;
- dw_writel(dev, ic_con, DW_IC_CON);
+ ic_con &= ~DW_IC_CON_10BITADDR_MASTER;
  }
 
+ dw_writel(dev, ic_con, DW_IC_CON);
+
  /*
  * Set the slave (target) address and enable 10-bit addressing mode
  * if applicable.
@@ -923,34 +921,13 @@ int i2c_dw_probe(struct dw_i2c_dev *dev)
 {
  struct i2c_adapter *adap = &dev->adapter;
  int r;
- u32 reg;
 
  init_completion(&dev->cmd_complete);
 
  r = i2c_dw_init(dev);
  if (r)
  return r;
 
- r = i2c_dw_acquire_lock(dev);
- if (r)
- return r;
-
- /*
- * Test if dynamic TAR update is enabled in this controller by writing
- * to IC_10BITADDR_MASTER field in IC_CON: when it is enabled this
- * field is read-only so it should not succeed
- */
- reg = dw_readl(dev, DW_IC_CON);
- dw_writel(dev, reg ^ DW_IC_CON_10BITADDR_MASTER, DW_IC_CON);
-
- if ((dw_readl(dev, DW_IC_CON) & DW_IC_CON_10BITADDR_MASTER) ==
- (reg & DW_IC_CON_10BITADDR_MASTER)) {
- dev->dynamic_tar_update_enabled = true;
- dev_dbg(dev->dev, "Dynamic TAR update enabled");
- }
-
- i2c_dw_release_lock(dev);
-
  snprintf(adap->name, sizeof(adap->name),
  "Synopsys DesignWare I2C adapter");
  adap->retries = 3;

drivers/i2c/busses/i2c-designware-core.h

@@ -117,7 +117,6 @@ struct dw_i2c_dev {
  int (*acquire_lock)(struct dw_i2c_dev *dev);
  void (*release_lock)(struct dw_i2c_dev *dev);
  bool pm_runtime_disabled;
- bool dynamic_tar_update_enabled;
 };
 
 #define ACCESS_SWAP 0x00000001