This patch enables the indexed write feature of the GMBUS to concatenate
2 consecutive messages into one. The criteria for an indexed write is
that both messages are writes, the first is length == 1, and the second
is length > 0. The first message is sent out by the GMBUS as the slave
command, and the second one is sent via the GMBUS FIFO as usual.
Changes in v3:
- Added to series
Changes in v4:
- Combine indexed reads and writes (Ville)
Changes in v5:
- checkpatch whitespace nits
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Suggested-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_i2c.c | 34 ++++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index ef9f91a0b0c9..d9e6993fa718 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -402,7 +402,8 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
static int
gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
- unsigned short addr, u8 *buf, unsigned int len)
+ unsigned short addr, u8 *buf, unsigned int len,
+ u32 gmbus1_index)
{
unsigned int chunk_size = len;
u32 val, loop;
@@ -415,7 +416,7 @@ gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
I915_WRITE_FW(GMBUS3, val);
I915_WRITE_FW(GMBUS1,
- GMBUS_CYCLE_WAIT |
+ gmbus1_index | GMBUS_CYCLE_WAIT |
(chunk_size << GMBUS_BYTE_COUNT_SHIFT) |
(addr << GMBUS_SLAVE_ADDR_SHIFT) |
GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
@@ -438,7 +439,8 @@ gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
}
static int
-gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
+gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
+ u32 gmbus1_index)
{
u8 *buf = msg->buf;
unsigned int tx_size = msg->len;
@@ -448,7 +450,8 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
do {
len = min(tx_size, GMBUS_BYTE_COUNT_MAX);
- ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len);
+ ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len,
+ gmbus1_index);
if (ret)
return ret;
@@ -460,21 +463,21 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
}
/*
- * The gmbus controller can combine a 1 or 2 byte write with a read that
- * immediately follows it by using an "INDEX" cycle.
+ * The gmbus controller can combine a 1 or 2 byte write with another read/write
+ * that immediately follows it by using an "INDEX" cycle.
*/
static bool
-gmbus_is_index_read(struct i2c_msg *msgs, int i, int num)
+gmbus_is_index_xfer(struct i2c_msg *msgs, int i, int num)
{
return (i + 1 < num &&
msgs[i].addr == msgs[i + 1].addr &&
!(msgs[i].flags & I2C_M_RD) &&
(msgs[i].len == 1 || msgs[i].len == 2) &&
- (msgs[i + 1].flags & I2C_M_RD));
+ msgs[i + 1].len > 0);
}
static int
-gmbus_xfer_index_read(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
+gmbus_index_xfer(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
{
u32 gmbus1_index = 0;
u32 gmbus5 = 0;
@@ -491,7 +494,10 @@ gmbus_xfer_index_read(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
if (gmbus5)
I915_WRITE_FW(GMBUS5, gmbus5);
- ret = gmbus_xfer_read(dev_priv, &msgs[1], gmbus1_index);
+ if (msgs[1].flags & I2C_M_RD)
+ ret = gmbus_xfer_read(dev_priv, &msgs[1], gmbus1_index);
+ else
+ ret = gmbus_xfer_write(dev_priv, &msgs[1], gmbus1_index);
/* Clear GMBUS5 after each index transfer */
if (gmbus5)
@@ -522,13 +528,13 @@ do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
for (; i < num; i += inc) {
inc = 1;
- if (gmbus_is_index_read(msgs, i, num)) {
- ret = gmbus_xfer_index_read(dev_priv, &msgs[i]);
- inc = 2; /* an index read is two msgs */
+ if (gmbus_is_index_xfer(msgs, i, num)) {
+ ret = gmbus_index_xfer(dev_priv, &msgs[i]);
+ inc = 2; /* an index transmission is two msgs */
} else if (msgs[i].flags & I2C_M_RD) {
ret = gmbus_xfer_read(dev_priv, &msgs[i], 0);
} else {
- ret = gmbus_xfer_write(dev_priv, &msgs[i]);
+ ret = gmbus_xfer_write(dev_priv, &msgs[i], 0);
}
if (!ret)
--
2.16.0.rc0.223.g4a4ac83678-goog
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