4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Deucher <alexander.deucher@xxxxxxx> commit 5292221d6ddfed75e5b46cd42237a677094b99f3 upstream. This reverts commit 018d82e5f02ef3583411bcaa4e00c69786f46f19. This breaks DDC in certain cases. Revert for 4.18 and previous kernels. For 4.19, this is fixed with the following more extensive patches: drm/amd/display: Serialize is_dp_sink_present drm/amd/display: Break out function to simply read aux reply drm/amd/display: Return aux replies directly to DRM drm/amd/display: Right shift AUX reply value sooner than later drm/amd/display: Read AUX channel even if only status byte is returned Link: https://lists.freedesktop.org/archives/amd-gfx/2018-July/023788.html Acked-by: Harry Wentland <harry.wentland@xxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 20 ++++-------- drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c | 10 +----- drivers/gpu/drm/amd/display/dc/inc/dc_link_ddc.h | 5 +-- 3 files changed, 13 insertions(+), 22 deletions(-) --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -83,22 +83,21 @@ static ssize_t dm_dp_aux_transfer(struct enum i2c_mot_mode mot = (msg->request & DP_AUX_I2C_MOT) ? I2C_MOT_TRUE : I2C_MOT_FALSE; enum ddc_result res; - uint32_t read_bytes = msg->size; + ssize_t read_bytes; if (WARN_ON(msg->size > 16)) return -E2BIG; switch (msg->request & ~DP_AUX_I2C_MOT) { case DP_AUX_NATIVE_READ: - res = dal_ddc_service_read_dpcd_data( + read_bytes = dal_ddc_service_read_dpcd_data( TO_DM_AUX(aux)->ddc_service, false, I2C_MOT_UNDEF, msg->address, msg->buffer, - msg->size, - &read_bytes); - break; + msg->size); + return read_bytes; case DP_AUX_NATIVE_WRITE: res = dal_ddc_service_write_dpcd_data( TO_DM_AUX(aux)->ddc_service, @@ -109,15 +108,14 @@ static ssize_t dm_dp_aux_transfer(struct msg->size); break; case DP_AUX_I2C_READ: - res = dal_ddc_service_read_dpcd_data( + read_bytes = dal_ddc_service_read_dpcd_data( TO_DM_AUX(aux)->ddc_service, true, mot, msg->address, msg->buffer, - msg->size, - &read_bytes); - break; + msg->size); + return read_bytes; case DP_AUX_I2C_WRITE: res = dal_ddc_service_write_dpcd_data( TO_DM_AUX(aux)->ddc_service, @@ -139,9 +137,7 @@ static ssize_t dm_dp_aux_transfer(struct r == DDC_RESULT_SUCESSFULL); #endif - if (res != DDC_RESULT_SUCESSFULL) - return -EIO; - return read_bytes; + return msg->size; } static enum drm_connector_status --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c @@ -629,14 +629,13 @@ bool dal_ddc_service_query_ddc_data( return ret; } -enum ddc_result dal_ddc_service_read_dpcd_data( +ssize_t dal_ddc_service_read_dpcd_data( struct ddc_service *ddc, bool i2c, enum i2c_mot_mode mot, uint32_t address, uint8_t *data, - uint32_t len, - uint32_t *read) + uint32_t len) { struct aux_payload read_payload = { .i2c_over_aux = i2c, @@ -653,8 +652,6 @@ enum ddc_result dal_ddc_service_read_dpc .mot = mot }; - *read = 0; - if (len > DEFAULT_AUX_MAX_DATA_SIZE) { BREAK_TO_DEBUGGER(); return DDC_RESULT_FAILED_INVALID_OPERATION; @@ -664,8 +661,7 @@ enum ddc_result dal_ddc_service_read_dpc ddc->ctx->i2caux, ddc->ddc_pin, &command)) { - *read = command.payloads->length; - return DDC_RESULT_SUCESSFULL; + return (ssize_t)command.payloads->length; } return DDC_RESULT_FAILED_OPERATION; --- a/drivers/gpu/drm/amd/display/dc/inc/dc_link_ddc.h +++ b/drivers/gpu/drm/amd/display/dc/inc/dc_link_ddc.h @@ -102,14 +102,13 @@ bool dal_ddc_service_query_ddc_data( uint8_t *read_buf, uint32_t read_size); -enum ddc_result dal_ddc_service_read_dpcd_data( +ssize_t dal_ddc_service_read_dpcd_data( struct ddc_service *ddc, bool i2c, enum i2c_mot_mode mot, uint32_t address, uint8_t *data, - uint32_t len, - uint32_t *read); + uint32_t len); enum ddc_result dal_ddc_service_write_dpcd_data( struct ddc_service *ddc,
