drm/i915: i2c: unconditionally set up gpio fallback

This way we can simplify the setup and teardown a bit.

Because we don't actually allocate anything anymore for the force_bit
case, we can now convert that into a boolean.

Also and the functionality supported by the bit-banging together with
what gmbus can do, so that this doesn't randomly change any more.

v2: Chris Wilson noticed that I've mixed up && and & ...

v3: Clarify an if block as suggested by Eugeni Dodonov.

Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

2 files changed, 22 insertions, 32 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 47b315ca2ca..c0f19f57200 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -301,7 +301,8 @@ struct intel_fbc_work;
 
 struct intel_gmbus {
         struct i2c_adapter adapter;
-        struct i2c_adapter *force_bit;
+        bool force_bit;
+        bool has_gpio;
         u32 reg0;
         u32 gpio_reg;
         struct i2c_algo_bit_data bit_algo;
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 43dde957a32..8fdc9570021 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -140,8 +140,8 @@ static void set_data(void *data, int state_high)
         POSTING_READ(bus->gpio_reg);
 }
 
-static struct i2c_adapter *
-intel_gpio_create(struct intel_gmbus *bus, u32 pin)
+static bool
+intel_gpio_setup(struct intel_gmbus *bus, u32 pin)
 {
         struct drm_i915_private *dev_priv = bus->dev_priv;
         static const int map_pin_to_reg[] = {
@@ -157,7 +157,7 @@ intel_gpio_create(struct intel_gmbus *bus, u32 pin)
         struct i2c_algo_bit_data *algo;
 
         if (pin >= ARRAY_SIZE(map_pin_to_reg) || !map_pin_to_reg[pin])
-                return NULL;
+                return false;
 
         algo = &bus->bit_algo;
 
@@ -174,12 +174,11 @@ intel_gpio_create(struct intel_gmbus *bus, u32 pin)
         algo->timeout = usecs_to_jiffies(2200);
         algo->data = bus;
 
-        return &bus->adapter;
+        return true;
 }
 
 static int
 intel_i2c_quirk_xfer(struct intel_gmbus *bus,
-                     struct i2c_adapter *adapter,
                      struct i2c_msg *msgs,
                      int num)
 {
@@ -193,7 +192,7 @@ intel_i2c_quirk_xfer(struct intel_gmbus *bus,
         set_clock(bus, 1);
         udelay(I2C_RISEFALL_TIME);
 
-        ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
+        ret = i2c_bit_algo.master_xfer(&bus->adapter, msgs, num);
 
         set_data(bus, 1);
         set_clock(bus, 1);
@@ -216,7 +215,7 @@ gmbus_xfer(struct i2c_adapter *adapter,
         mutex_lock(&dev_priv->gmbus_mutex);
 
         if (bus->force_bit) {
-                ret = intel_i2c_quirk_xfer(bus, bus->force_bit, msgs, num);
+                ret = intel_i2c_quirk_xfer(bus, msgs, num);
                 goto out;
         }
 
@@ -316,11 +315,12 @@ timeout:
         I915_WRITE(GMBUS0 + reg_offset, 0);
 
         /* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
-        bus->force_bit = intel_gpio_create(bus, bus->reg0 & 0xff);
-        if (!bus->force_bit)
-                ret = -ENOMEM;
-        else
-                ret = intel_i2c_quirk_xfer(bus, bus->force_bit, msgs, num);
+        if (!bus->has_gpio) {
+                ret = -EIO;
+        } else {
+                bus->force_bit = true;
+                ret = intel_i2c_quirk_xfer(bus, msgs, num);
+        }
 out:
         mutex_unlock(&dev_priv->gmbus_mutex);
         return ret;
@@ -328,14 +328,8 @@ out:
 
 static u32 gmbus_func(struct i2c_adapter *adapter)
 {
-        struct intel_gmbus *bus = container_of(adapter,
-                                               struct intel_gmbus,
-                                               adapter);
-
-        if (bus->force_bit)
-                i2c_bit_algo.functionality(bus->force_bit);
-
-        return (I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+        return i2c_bit_algo.functionality(adapter) &
+                (I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
                 /* I2C_FUNC_10BIT_ADDR | */
                 I2C_FUNC_SMBUS_READ_BLOCK_DATA |
                 I2C_FUNC_SMBUS_BLOCK_PROC_CALL);
@@ -393,8 +387,11 @@ int intel_setup_gmbus(struct drm_device *dev)
                 /* By default use a conservative clock rate */
                 bus->reg0 = i | GMBUS_RATE_100KHZ;
 
+                bus->has_gpio = intel_gpio_setup(bus, i);
+
                 /* XXX force bit banging until GMBUS is fully debugged */
-                bus->force_bit = intel_gpio_create(bus, i);
+                if (bus->has_gpio)
+                        bus->force_bit = true;
         }
 
         intel_i2c_reset(dev_priv->dev);
@@ -422,16 +419,8 @@ void intel_gmbus_force_bit(struct i2c_adapter *adapter, bool force_bit)
 {
         struct intel_gmbus *bus = to_intel_gmbus(adapter);
 
-        if (force_bit) {
-                if (bus->force_bit == NULL) {
-                        bus->force_bit = intel_gpio_create(bus,
-                                                           bus->reg0 & 0xff);
-                }
-        } else {
-                if (bus->force_bit) {
-                        bus->force_bit = NULL;
-                }
-        }
+        if (bus->has_gpio)
+                bus->force_bit = force_bit;
 }
 
 void intel_teardown_gmbus(struct drm_device *dev)