drm/i915: abstract i2c bit banging fallback in gmbus xfer

Choose between i2c bit banging and gmbus in a new higher level function,
and let the i2c core retry the first time we fall back to bit banging.

The i2c core imposes a timeout on -EAGAIN, but it defaults to 1 second,
and shouldn't be a problem for us.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448980166-23055-2-git-send-email-jani.nikula@intel.com
This commit is contained in:
Jani Nikula 2015-12-01 16:29:26 +02:00
Родитель 0aeb904888
Коммит bffce907d6
1 изменённых файлов: 25 добавлений и 14 удалений

Просмотреть файл

@ -472,9 +472,7 @@ gmbus_xfer_index_read(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
}
static int
gmbus_xfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs,
int num)
do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
{
struct intel_gmbus *bus = container_of(adapter,
struct intel_gmbus,
@ -483,14 +481,6 @@ gmbus_xfer(struct i2c_adapter *adapter,
int i = 0, inc, try = 0;
int ret = 0;
intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
mutex_lock(&dev_priv->gmbus_mutex);
if (bus->force_bit) {
ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
goto out;
}
retry:
I915_WRITE(GMBUS0, bus->reg0);
@ -585,13 +575,34 @@ timeout:
bus->adapter.name, bus->reg0 & 0xff);
I915_WRITE(GMBUS0, 0);
/* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
/*
* Hardware may not support GMBUS over these pins? Try GPIO bitbanging
* instead. Use EAGAIN to have i2c core retry.
*/
bus->force_bit = 1;
ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
ret = -EAGAIN;
out:
mutex_unlock(&dev_priv->gmbus_mutex);
return ret;
}
static int
gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
{
struct intel_gmbus *bus = container_of(adapter, struct intel_gmbus,
adapter);
struct drm_i915_private *dev_priv = bus->dev_priv;
int ret;
intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
mutex_lock(&dev_priv->gmbus_mutex);
if (bus->force_bit)
ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
else
ret = do_gmbus_xfer(adapter, msgs, num);
mutex_unlock(&dev_priv->gmbus_mutex);
intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
return ret;