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drm/i915: Rework sdvo proxy i2c locking

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lockdep complaints about a locking recursion for the i2c bus lock
because both the sdvo ddc proxy bus and the gmbus nested within use
the same locking class. It's not really a deadlock since we never nest
the other way round, but it's annoying.

Fix it by pulling the gmbus locking into the i2c lock_ops for both
i2c_adapater and making sure that the ddc_proxy_xfer function is
entirely lockless.

Re-layouting the extracted function resulted in some whitespace
cleanups, I figured we might as well keep them.

v2: Review from Chris:
- s/locked/unlocked/ since I got the naming backwards
- Use the vfuncs of the proxied adatper instead of re-rolling copies.
  That's more consistent with the other proxying we're doing.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170726132647.31833-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2017-07-26 15:26:47 +02:00
parent 8fb6a5df46
commit a85066840d
2 changed files with 84 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
drivers/gpu/drm/i915/intel_i2c.c
View File

@ -592,7 +592,6 @@ gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
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);
@ -604,7 +603,6 @@ gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
bus->force_bit |= GMBUS_FORCE_BIT_RETRY;
}
mutex_unlock(&dev_priv->gmbus_mutex);
intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
return ret;
@ -624,6 +622,39 @@ static const struct i2c_algorithm gmbus_algorithm = {
.functionality = gmbus_func
};
static void gmbus_lock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
struct intel_gmbus *bus = to_intel_gmbus(adapter);
struct drm_i915_private *dev_priv = bus->dev_priv;
mutex_lock(&dev_priv->gmbus_mutex);
}
static int gmbus_trylock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
struct intel_gmbus *bus = to_intel_gmbus(adapter);
struct drm_i915_private *dev_priv = bus->dev_priv;
return mutex_trylock(&dev_priv->gmbus_mutex);
}
static void gmbus_unlock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
struct intel_gmbus *bus = to_intel_gmbus(adapter);
struct drm_i915_private *dev_priv = bus->dev_priv;
mutex_unlock(&dev_priv->gmbus_mutex);
}
const struct i2c_lock_operations gmbus_lock_ops = {
.lock_bus = gmbus_lock_bus,
.trylock_bus = gmbus_trylock_bus,
.unlock_bus = gmbus_unlock_bus,
};
/**
* intel_gmbus_setup - instantiate all Intel i2c GMBuses
* @dev_priv: i915 device private
@ -665,6 +696,7 @@ int intel_setup_gmbus(struct drm_i915_private *dev_priv)
bus->dev_priv = dev_priv;
bus->adapter.algo = &gmbus_algorithm;
bus->adapter.lock_ops = &gmbus_lock_ops;
/*
* We wish to retry with bit banging

62
drivers/gpu/drm/i915/intel_sdvo.c
View File

@ -451,23 +451,24 @@ static const char * const cmd_status_names[] = {
"Scaling not supported"
};
static bool intel_sdvo_write_cmd(struct intel_sdvo *intel_sdvo, u8 cmd,
const void *args, int args_len)
static bool __intel_sdvo_write_cmd(struct intel_sdvo *intel_sdvo, u8 cmd,
const void *args, int args_len,
bool unlocked)
{
u8 *buf, status;
struct i2c_msg *msgs;
int i, ret = true;
/* Would be simpler to allocate both in one go ? */
/* Would be simpler to allocate both in one go ? */
buf = kzalloc(args_len * 2 + 2, GFP_KERNEL);
if (!buf)
return false;
msgs = kcalloc(args_len + 3, sizeof(*msgs), GFP_KERNEL);
if (!msgs) {
kfree(buf);
kfree(buf);
return false;
}
}
intel_sdvo_debug_write(intel_sdvo, cmd, args, args_len);
@ -498,7 +499,10 @@ static bool intel_sdvo_write_cmd(struct intel_sdvo *intel_sdvo, u8 cmd,
msgs[i+2].len = 1;
msgs[i+2].buf = &status;
ret = i2c_transfer(intel_sdvo->i2c, msgs, i+3);
if (unlocked)
ret = i2c_transfer(intel_sdvo->i2c, msgs, i+3);
else
ret = __i2c_transfer(intel_sdvo->i2c, msgs, i+3);
if (ret < 0) {
DRM_DEBUG_KMS("I2c transfer returned %d\n", ret);
ret = false;
@ -516,6 +520,12 @@ static bool intel_sdvo_write_cmd(struct intel_sdvo *intel_sdvo, u8 cmd,
return ret;
}
static bool intel_sdvo_write_cmd(struct intel_sdvo *intel_sdvo, u8 cmd,
const void *args, int args_len)
{
return __intel_sdvo_write_cmd(intel_sdvo, cmd, args, args_len, true);
}
static bool intel_sdvo_read_response(struct intel_sdvo *intel_sdvo,
void *response, int response_len)
{
@ -602,13 +612,13 @@ static int intel_sdvo_get_pixel_multiplier(const struct drm_display_mode *adjust
return 4;
}
static bool intel_sdvo_set_control_bus_switch(struct intel_sdvo *intel_sdvo,
u8 ddc_bus)
static bool __intel_sdvo_set_control_bus_switch(struct intel_sdvo *intel_sdvo,
u8 ddc_bus)
{
/* This must be the immediately preceding write before the i2c xfer */
return intel_sdvo_write_cmd(intel_sdvo,
SDVO_CMD_SET_CONTROL_BUS_SWITCH,
&ddc_bus, 1);
return __intel_sdvo_write_cmd(intel_sdvo,
SDVO_CMD_SET_CONTROL_BUS_SWITCH,
&ddc_bus, 1, false);
}
static bool intel_sdvo_set_value(struct intel_sdvo *intel_sdvo, u8 cmd, const void *data, int len)
@ -2926,7 +2936,7 @@ static int intel_sdvo_ddc_proxy_xfer(struct i2c_adapter *adapter,
{
struct intel_sdvo *sdvo = adapter->algo_data;
if (!intel_sdvo_set_control_bus_switch(sdvo, sdvo->ddc_bus))
if (!__intel_sdvo_set_control_bus_switch(sdvo, sdvo->ddc_bus))
return -EIO;
return sdvo->i2c->algo->master_xfer(sdvo->i2c, msgs, num);
@ -2943,6 +2953,33 @@ static const struct i2c_algorithm intel_sdvo_ddc_proxy = {
.functionality = intel_sdvo_ddc_proxy_func
};
static void proxy_lock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
struct intel_sdvo *sdvo = adapter->algo_data;
sdvo->i2c->lock_ops->lock_bus(sdvo->i2c, flags);
}
static int proxy_trylock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
struct intel_sdvo *sdvo = adapter->algo_data;
return sdvo->i2c->lock_ops->trylock_bus(sdvo->i2c, flags);
}
static void proxy_unlock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
struct intel_sdvo *sdvo = adapter->algo_data;
sdvo->i2c->lock_ops->unlock_bus(sdvo->i2c, flags);
}
const struct i2c_lock_operations proxy_lock_ops = {
.lock_bus = proxy_lock_bus,
.trylock_bus = proxy_trylock_bus,
.unlock_bus = proxy_unlock_bus,
};
static bool
intel_sdvo_init_ddc_proxy(struct intel_sdvo *sdvo,
struct drm_i915_private *dev_priv)
@ -2955,6 +2992,7 @@ intel_sdvo_init_ddc_proxy(struct intel_sdvo *sdvo,
sdvo->ddc.dev.parent = &pdev->dev;
sdvo->ddc.algo_data = sdvo;
sdvo->ddc.algo = &intel_sdvo_ddc_proxy;
sdvo->ddc.lock_ops = &proxy_lock_ops;
return i2c_add_adapter(&sdvo->ddc) == 0;
}