Hi all, Today's linux-next merge of the drm-misc tree got a conflict in: drivers/gpu/drm/drm_dp_helper.c between commits: 79a2b161c12a ("drm/dp: Define AUX_RETRY_INTERVAL as 500 us") 4efa83c8c786 ("drm/dp: Adjust i2c-over-aux retry count based on message size and i2c bus speed") f36203be608a ("drm/dp: Add dp_aux_i2c_speed_khz module param to set the assume i2c bus speed") from Linus' tree and commit: 68ec2a2a2481 ("drm/dp: Use I2C_WRITE_STATUS_UPDATE to drain partial I2C_WRITE requests") from the drm-misc tree. I fixed it up (see below) and can carry the fix as necessary (no action is required). -- Cheers, Stephen Rothwell sfr@xxxxxxxxxxxxxxxx diff --cc drivers/gpu/drm/drm_dp_helper.c index 291734e87fca,5a55d905b8ee..000000000000 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@@ -424,90 -422,19 +424,103 @@@ static u32 drm_dp_i2c_functionality(str I2C_FUNC_10BIT_ADDR; } +#define AUX_PRECHARGE_LEN 10 /* 10 to 16 */ +#define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */ +#define AUX_STOP_LEN 4 +#define AUX_CMD_LEN 4 +#define AUX_ADDRESS_LEN 20 +#define AUX_REPLY_PAD_LEN 4 +#define AUX_LENGTH_LEN 8 + +/* + * Calculate the duration of the AUX request/reply in usec. Gives the + * "best" case estimate, ie. successful while as short as possible. + */ +static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg *msg) +{ + int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN + + AUX_CMD_LEN + AUX_ADDRESS_LEN + AUX_LENGTH_LEN; + + if ((msg->request & DP_AUX_I2C_READ) == 0) + len += msg->size * 8; + + return len; +} + +static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg *msg) +{ + int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN + + AUX_CMD_LEN + AUX_REPLY_PAD_LEN; + + /* + * For read we expect what was asked. For writes there will + * be 0 or 1 data bytes. Assume 0 for the "best" case. + */ + if (msg->request & DP_AUX_I2C_READ) + len += msg->size * 8; + + return len; +} + +#define I2C_START_LEN 1 +#define I2C_STOP_LEN 1 +#define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */ +#define I2C_DATA_LEN 9 /* DATA + ACK/NACK */ + +/* + * Calculate the length of the i2c transfer in usec, assuming + * the i2c bus speed is as specified. Gives the the "worst" + * case estimate, ie. successful while as long as possible. + * Doesn't account the the "MOT" bit, and instead assumes each + * message includes a START, ADDRESS and STOP. Neither does it + * account for additional random variables such as clock stretching. + */ +static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg *msg, + int i2c_speed_khz) +{ + /* AUX bitrate is 1MHz, i2c bitrate as specified */ + return DIV_ROUND_UP((I2C_START_LEN + I2C_ADDR_LEN + + msg->size * I2C_DATA_LEN + + I2C_STOP_LEN) * 1000, i2c_speed_khz); +} + +/* + * Deterine how many retries should be attempted to successfully transfer + * the specified message, based on the estimated durations of the + * i2c and AUX transfers. + */ +static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg *msg, + int i2c_speed_khz) +{ + int aux_time_us = drm_dp_aux_req_duration(msg) + + drm_dp_aux_reply_duration(msg); + int i2c_time_us = drm_dp_i2c_msg_duration(msg, i2c_speed_khz); + + return DIV_ROUND_UP(i2c_time_us, aux_time_us + AUX_RETRY_INTERVAL); +} + +/* + * FIXME currently assumes 10 kHz as some real world devices seem + * to require it. We should query/set the speed via DPCD if supported. + */ +static int dp_aux_i2c_speed_khz __read_mostly = 10; +module_param_unsafe(dp_aux_i2c_speed_khz, int, 0644); +MODULE_PARM_DESC(dp_aux_i2c_speed_khz, + "Assumed speed of the i2c bus in kHz, (1-400, default 10)"); + + 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 @@@ -595,7 -521,8 +610,8 @@@ static int drm_dp_i2c_do_msg(struct drm aux->i2c_defer_count++; if (defer_i2c < 7) defer_i2c++; - usleep_range(400, 500); + usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); + drm_dp_i2c_msg_write_status_update(msg); continue; default: _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel