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Subject[PATCH 4.17 31/63] Revert "drm/amd/display: Dont return ddc result and read_bytes in same return value"
Date
4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Deucher <alexander.deucher@amd.com>

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@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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,

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