From 68ec2a2a24815c0ee359b1327b60a276cd2280d8 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Thu, 27 Aug 2015 17:23:30 +0300 Subject: [PATCH] drm/dp: Use I2C_WRITE_STATUS_UPDATE to drain partial I2C_WRITE requests MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When an i2c WRITE gets an i2c defer or short i2c ack reply, we are supposed to switch the request from I2C_WRITE to I2C_WRITE_STATUS_UPDATE when we continue to poll for the completion of the request. v2: Don't assume DP_AUX_I2C_WRITE is 0 even though it is, to make the code more obvious to the casual reader (Jani) Acked-by: Alex Deucher Reviewed-by: Jani Nikula Signed-off-by: Ville Syrjälä [danvet: Resolve conflict due to changed context.] Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_dp_helper.c | 43 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 39 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 80a02a4..5a55d90 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -422,6 +422,19 @@ static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter) I2C_FUNC_10BIT_ADDR; } +static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg) +{ + /* + * In case of i2c defer or short i2c ack reply to a write, + * we need to switch to WRITE_STATUS_UPDATE to drain the + * rest of the message + */ + if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_I2C_WRITE) { + msg->request &= DP_AUX_I2C_MOT; + msg->request |= DP_AUX_I2C_WRITE_STATUS_UPDATE; + } +} + /* * Transfer a single I2C-over-AUX message and handle various error conditions, * retrying the transaction as appropriate. It is assumed that the @@ -490,6 +503,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) * Both native ACK and I2C ACK replies received. We * can assume the transfer was successful. */ + if (ret != msg->size) + drm_dp_i2c_msg_write_status_update(msg); return ret; case DP_AUX_I2C_REPLY_NACK: @@ -507,6 +522,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) if (defer_i2c < 7) defer_i2c++; usleep_range(400, 500); + drm_dp_i2c_msg_write_status_update(msg); continue; default: @@ -519,6 +535,14 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) return -EREMOTEIO; } +static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg, + const struct i2c_msg *i2c_msg) +{ + msg->request = (i2c_msg->flags & I2C_M_RD) ? + DP_AUX_I2C_READ : DP_AUX_I2C_WRITE; + msg->request |= DP_AUX_I2C_MOT; +} + /* * Keep retrying drm_dp_i2c_do_msg until all data has been transferred. * @@ -572,10 +596,7 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, for (i = 0; i < num; i++) { msg.address = msgs[i].addr; - msg.request = (msgs[i].flags & I2C_M_RD) ? - DP_AUX_I2C_READ : - DP_AUX_I2C_WRITE; - msg.request |= DP_AUX_I2C_MOT; + drm_dp_i2c_msg_set_request(&msg, &msgs[i]); /* Send a bare address packet to start the transaction. * Zero sized messages specify an address only (bare * address) transaction. @@ -583,6 +604,13 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, msg.buffer = NULL; msg.size = 0; err = drm_dp_i2c_do_msg(aux, &msg); + + /* + * Reset msg.request in case in case it got + * changed into a WRITE_STATUS_UPDATE. + */ + drm_dp_i2c_msg_set_request(&msg, &msgs[i]); + if (err < 0) break; /* We want each transaction to be as large as possible, but @@ -595,6 +623,13 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, msg.size = min(transfer_size, msgs[i].len - j); err = drm_dp_i2c_drain_msg(aux, &msg); + + /* + * Reset msg.request in case in case it got + * changed into a WRITE_STATUS_UPDATE. + */ + drm_dp_i2c_msg_set_request(&msg, &msgs[i]); + if (err < 0) break; transfer_size = err; -- 2.7.4