drm/nv50: use custom i2c algo for dp auxch

This makes it easier to see how this is working, and lets us transfer the
EDID in blocks of 16 bytes.

The primary reason for this change is because debug logs are rather hard
to read with the hundreds of single-byte auxch transactions that occur.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 52 insertions, 35 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 33742b11188..8a1b188b4cd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -572,47 +572,64 @@ out:
 	return ret ? ret : (stat & NV50_AUXCH_STAT_REPLY);
 }
 
-int
-nouveau_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
-		      uint8_t write_byte, uint8_t *read_byte)
+static int
+nouveau_dp_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 {
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	struct nouveau_i2c_chan *auxch = (struct nouveau_i2c_chan *)adapter;
+	struct nouveau_i2c_chan *auxch = (struct nouveau_i2c_chan *)adap;
 	struct drm_device *dev = auxch->dev;
-	int ret = 0, cmd, addr = algo_data->address;
-	uint8_t *buf;
-
-	if (mode == MODE_I2C_READ) {
-		cmd = AUX_I2C_READ;
-		buf = read_byte;
-	} else {
-		cmd = (mode & MODE_I2C_READ) ? AUX_I2C_READ : AUX_I2C_WRITE;
-		buf = &write_byte;
-	}
+	struct i2c_msg *msg = msgs;
+	int ret, mcnt = num;
 
-	if (!(mode & MODE_I2C_STOP))
-		cmd |= AUX_I2C_MOT;
+	while (mcnt--) {
+		u8 remaining = msg->len;
+		u8 *ptr = msg->buf;
 
-	if (mode & MODE_I2C_START)
-		return 1;
+		while (remaining) {
+			u8 cnt = (remaining > 16) ? 16 : remaining;
+			u8 cmd;
 
-	for (;;) {
-		ret = nouveau_dp_auxch(auxch, cmd, addr, buf, 1);
-		if (ret < 0)
-			return ret;
-
-		switch (ret & NV50_AUXCH_STAT_REPLY_I2C) {
-		case NV50_AUXCH_STAT_REPLY_I2C_ACK:
-			return 1;
-		case NV50_AUXCH_STAT_REPLY_I2C_NACK:
-			return -EREMOTEIO;
-		case NV50_AUXCH_STAT_REPLY_I2C_DEFER:
-			udelay(100);
-			break;
-		default:
-			NV_ERROR(dev, "invalid auxch status: 0x%08x\n", ret);
-			return -EREMOTEIO;
+			if (msg->flags & I2C_M_RD)
+				cmd = AUX_I2C_READ;
+			else
+				cmd = AUX_I2C_WRITE;
+
+			if (mcnt || remaining > 16)
+				cmd |= AUX_I2C_MOT;
+
+			ret = nouveau_dp_auxch(auxch, cmd, msg->addr, ptr, cnt);
+			if (ret < 0)
+				return ret;
+
+			switch (ret & NV50_AUXCH_STAT_REPLY_I2C) {
+			case NV50_AUXCH_STAT_REPLY_I2C_ACK:
+				break;
+			case NV50_AUXCH_STAT_REPLY_I2C_NACK:
+				return -EREMOTEIO;
+			case NV50_AUXCH_STAT_REPLY_I2C_DEFER:
+				udelay(100);
+				continue;
+			default:
+				NV_ERROR(dev, "bad auxch reply: 0x%08x\n", ret);
+				return -EREMOTEIO;
+			}
+
+			ptr += cnt;
+			remaining -= cnt;
 		}
+
+		msg++;
 	}
+
+	return num;
+}
+
+static u32
+nouveau_dp_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }
 
+const struct i2c_algorithm nouveau_dp_i2c_algo = {
+	.master_xfer = nouveau_dp_i2c_xfer,
+	.functionality = nouveau_dp_i2c_func
+};