From: Lin Huang <h...@rock-chips.com>

We need to check the dpcd write/read return value to see whether the
write/read was successful

Cc: Kristian H. Kristensen <hoegsb...@chromium.org>
Signed-off-by: Lin Huang <h...@rock-chips.com>
Signed-off-by: zain wang <w...@rock-chips.com>
Signed-off-by: Douglas Anderson <diand...@chromium.org>
Signed-off-by: Sean Paul <seanp...@chromium.org>
Signed-off-by: Thierry Escande <thierry.esca...@collabora.com>
Reviewed-by: Andrzej Hajda <a.ha...@samsung.com>
Signed-off-by: Enric Balletbo i Serra <enric.balle...@collabora.com>
---

 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 169 ++++++++++++++++-----
 1 file changed, 127 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 5489570ef010..2d49ee6fd2f3 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -160,80 +160,137 @@ int analogix_dp_disable_psr(struct analogix_dp_device 
*dp)
 }
 EXPORT_SYMBOL_GPL(analogix_dp_disable_psr);
 
-static bool analogix_dp_detect_sink_psr(struct analogix_dp_device *dp)
+static int analogix_dp_detect_sink_psr(struct analogix_dp_device *dp)
 {
        unsigned char psr_version;
+       int ret;
+
+       ret = drm_dp_dpcd_readb(&dp->aux, DP_PSR_SUPPORT, &psr_version);
+       if (ret != 1) {
+               dev_err(dp->dev, "failed to get PSR version, disable it\n");
+               return ret;
+       }
 
-       drm_dp_dpcd_readb(&dp->aux, DP_PSR_SUPPORT, &psr_version);
        dev_dbg(dp->dev, "Panel PSR version : %x\n", psr_version);
 
-       return (psr_version & DP_PSR_IS_SUPPORTED) ? true : false;
+       dp->psr_enable = (psr_version & DP_PSR_IS_SUPPORTED) ? true : false;
+
+       return 0;
 }
 
-static void analogix_dp_enable_sink_psr(struct analogix_dp_device *dp)
+static int analogix_dp_enable_sink_psr(struct analogix_dp_device *dp)
 {
        unsigned char psr_en;
+       int ret;
 
        /* Disable psr function */
-       drm_dp_dpcd_readb(&dp->aux, DP_PSR_EN_CFG, &psr_en);
+       ret = drm_dp_dpcd_readb(&dp->aux, DP_PSR_EN_CFG, &psr_en);
+       if (ret != 1) {
+               dev_err(dp->dev, "failed to get psr config\n");
+               goto end;
+       }
+
        psr_en &= ~DP_PSR_ENABLE;
-       drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
+       ret = drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
+       if (ret != 1) {
+               dev_err(dp->dev, "failed to disable panel psr\n");
+               goto end;
+       }
 
        /* Main-Link transmitter remains active during PSR active states */
        psr_en = DP_PSR_MAIN_LINK_ACTIVE | DP_PSR_CRC_VERIFICATION;
-       drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
+       ret = drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
+       if (ret != 1) {
+               dev_err(dp->dev, "failed to set panel psr\n");
+               goto end;
+       }
 
        /* Enable psr function */
        psr_en = DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE |
                 DP_PSR_CRC_VERIFICATION;
-       drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
+       ret = drm_dp_dpcd_writeb(&dp->aux, DP_PSR_EN_CFG, psr_en);
+       if (ret != 1) {
+               dev_err(dp->dev, "failed to set panel psr\n");
+               goto end;
+       }
 
        analogix_dp_enable_psr_crc(dp);
+
+       return 0;
+end:
+       dev_err(dp->dev, "enable psr fail, force to disable psr\n");
+       dp->psr_enable = false;
+
+       return ret;
 }
 
-static void
+static int
 analogix_dp_enable_rx_to_enhanced_mode(struct analogix_dp_device *dp,
                                       bool enable)
 {
        u8 data;
+       int ret;
 
-       drm_dp_dpcd_readb(&dp->aux, DP_LANE_COUNT_SET, &data);
+       ret = drm_dp_dpcd_readb(&dp->aux, DP_LANE_COUNT_SET, &data);
+       if (ret != 1)
+               return ret;
 
        if (enable)
-               drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
-                                  DP_LANE_COUNT_ENHANCED_FRAME_EN |
-                                       DPCD_LANE_COUNT_SET(data));
+               ret = drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
+                                        DP_LANE_COUNT_ENHANCED_FRAME_EN |
+                                        DPCD_LANE_COUNT_SET(data));
        else
-               drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
-                                  DPCD_LANE_COUNT_SET(data));
+               ret = drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET,
+                                        DPCD_LANE_COUNT_SET(data));
+
+       return ret < 0 ? ret : 0;
 }
 
-static int analogix_dp_is_enhanced_mode_available(struct analogix_dp_device 
*dp)
+static int analogix_dp_is_enhanced_mode_available(struct analogix_dp_device 
*dp,
+                                                 u8 *enhanced_mode_support)
 {
        u8 data;
-       int retval;
+       int ret;
 
-       drm_dp_dpcd_readb(&dp->aux, DP_MAX_LANE_COUNT, &data);
-       retval = DPCD_ENHANCED_FRAME_CAP(data);
+       ret = drm_dp_dpcd_readb(&dp->aux, DP_MAX_LANE_COUNT, &data);
+       if (ret != 1) {
+               *enhanced_mode_support = 0;
+               return ret;
+       }
 
-       return retval;
+       *enhanced_mode_support = DPCD_ENHANCED_FRAME_CAP(data);
+
+       return 0;
 }
 
-static void analogix_dp_set_enhanced_mode(struct analogix_dp_device *dp)
+static int analogix_dp_set_enhanced_mode(struct analogix_dp_device *dp)
 {
        u8 data;
+       int ret;
+
+       ret = analogix_dp_is_enhanced_mode_available(dp, &data);
+       if (ret < 0)
+               return ret;
+
+       ret = analogix_dp_enable_rx_to_enhanced_mode(dp, data);
+       if (ret < 0)
+               return ret;
 
-       data = analogix_dp_is_enhanced_mode_available(dp);
-       analogix_dp_enable_rx_to_enhanced_mode(dp, data);
        analogix_dp_enable_enhanced_mode(dp, data);
+
+       return 0;
 }
 
-static void analogix_dp_training_pattern_dis(struct analogix_dp_device *dp)
+static int analogix_dp_training_pattern_dis(struct analogix_dp_device *dp)
 {
+       int ret;
+
        analogix_dp_set_training_pattern(dp, DP_NONE);
 
-       drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
-                          DP_TRAINING_PATTERN_DISABLE);
+       ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
+                                DP_TRAINING_PATTERN_DISABLE);
+
+       return ret < 0 ? ret : 0;
 }
 
 static void
@@ -282,7 +339,11 @@ static int analogix_dp_link_start(struct 
analogix_dp_device *dp)
        if (retval < 0)
                return retval;
        /* set enhanced mode if available */
-       analogix_dp_set_enhanced_mode(dp);
+       retval = analogix_dp_set_enhanced_mode(dp);
+       if (retval < 0) {
+               dev_err(dp->dev, "failed to set enhance mode\n");
+               return retval;
+       }
 
        /* Set TX pre-emphasis to minimum */
        for (lane = 0; lane < lane_count; lane++)
@@ -567,10 +628,11 @@ static int analogix_dp_process_equalizer_training(struct 
analogix_dp_device *dp)
 
        if (!analogix_dp_channel_eq_ok(link_status, link_align, lane_count)) {
                /* traing pattern Set to Normal */
-               analogix_dp_training_pattern_dis(dp);
+               retval = analogix_dp_training_pattern_dis(dp);
+               if (retval < 0)
+                       return retval;
 
                dev_info(dp->dev, "Link Training success!\n");
-
                analogix_dp_get_link_bandwidth(dp, &reg);
                dp->link_train.link_rate = reg;
                dev_dbg(dp->dev, "final bandwidth = %.2x\n",
@@ -867,24 +929,32 @@ static int analogix_dp_config_video(struct 
analogix_dp_device *dp)
        return 0;
 }
 
-static void analogix_dp_enable_scramble(struct analogix_dp_device *dp,
-                                       bool enable)
+static int analogix_dp_enable_scramble(struct analogix_dp_device *dp,
+                                      bool enable)
 {
        u8 data;
+       int ret;
 
        if (enable) {
                analogix_dp_enable_scrambling(dp);
 
-               drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET, &data);
-               drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
+               ret = drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET,
+                                       &data);
+               if (ret != 1)
+                       return ret;
+               ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
                                   (u8)(data & ~DP_LINK_SCRAMBLING_DISABLE));
        } else {
                analogix_dp_disable_scrambling(dp);
 
-               drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET, &data);
-               drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
+               ret = drm_dp_dpcd_readb(&dp->aux, DP_TRAINING_PATTERN_SET,
+                                       &data);
+               if (ret != 1)
+                       return ret;
+               ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
                                   (u8)(data | DP_LINK_SCRAMBLING_DISABLE));
        }
+       return ret < 0 ? ret : 0;
 }
 
 static irqreturn_t analogix_dp_hardirq(int irq, void *arg)
@@ -939,23 +1009,36 @@ static int analogix_dp_commit(struct analogix_dp_device 
*dp)
                return ret;
        }
 
-       analogix_dp_enable_scramble(dp, 1);
+       ret = analogix_dp_enable_scramble(dp, 1);
+       if (ret < 0) {
+               dev_err(dp->dev, "can not enable scramble\n");
+               return ret;
+       }
 
        analogix_dp_init_video(dp);
        ret = analogix_dp_config_video(dp);
-       if (ret)
+       if (ret) {
                dev_err(dp->dev, "unable to config video\n");
+               return ret;
+       }
 
        /* Safe to enable the panel now */
        if (dp->plat_data->panel) {
-               if (drm_panel_enable(dp->plat_data->panel))
+               ret = drm_panel_enable(dp->plat_data->panel);
+               if (ret) {
                        DRM_ERROR("failed to enable the panel\n");
+                       return ret;
+               }
        }
 
-       dp->psr_enable = analogix_dp_detect_sink_psr(dp);
+       ret = analogix_dp_detect_sink_psr(dp);
+       if (ret)
+               return ret;
+
        if (dp->psr_enable)
-               analogix_dp_enable_sink_psr(dp);
-       return 0;
+               ret = analogix_dp_enable_sink_psr(dp);
+
+       return ret;
 }
 
 /*
@@ -1185,8 +1268,10 @@ static int analogix_dp_set_bridge(struct 
analogix_dp_device *dp)
        }
 
        ret = analogix_dp_commit(dp);
-       if (ret)
+       if (ret) {
+               DRM_ERROR("dp commit error, ret = %d\n", ret);
                goto out_dp_init;
+       }
 
        enable_irq(dp->irq);
        return 0;
-- 
2.16.1

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