[Why] There is no handling for I2C-read-over-AUX when receive reply of I2C_ACK|AUX_ACK followed by the total number of data bytes Fewer than LEN + 1

[How] Refer to DP v2.1: 2.11.7.1.6.3 & 2.11.7.1.6.4, repeat the identical I2C-read-over-AUX transaction with the updated LEN value equal to the original LEN value minus the total number of data bytes received so far.

Fixes: 68ec2a2a2481 ("drm/dp: Use I2C_WRITE_STATUS_UPDATE to drain partial I2C_WRITE requests") Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Jani Nikula jani.nikula@intel.com Cc: Mario Limonciello mario.limonciello@amd.com Cc: Harry Wentland harry.wentland@amd.com Cc: stable@vger.kernel.org Signed-off-by: Wayne Lin Wayne.Lin@amd.com --- drivers/gpu/drm/display/drm_dp_helper.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index 28f0708c3b27..938214a980a9 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -1812,10 +1812,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) drm_dbg_kms(aux->drm_dev, "%s: I2C partially ack (result=%d, size=%zu)\n", aux->name, ret, msg->size); - if (!(msg->request & DP_AUX_I2C_READ)) { - usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); + usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); + if (msg->request & DP_AUX_I2C_READ) + msg->size -= ret; + else drm_dp_i2c_msg_write_status_update(msg); - }

continue; }