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    SubjectRe: [PATCH v2 22/43] drm/bridge: analogix_dp: Check dpcd write/read status
    On Fri, Jan 26, 2018 at 02:16:49PM +0100, Thierry Escande wrote:
    > From: Lin Huang <hl@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 <hoegsberg@chromium.org>
    > Signed-off-by: Lin Huang <hl@rock-chips.com>
    > Signed-off-by: zain wang <wzz@rock-chips.com>
    > Signed-off-by: Douglas Anderson <dianders@chromium.org>
    > Signed-off-by: Sean Paul <seanpaul@chromium.org>
    > Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
    > Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
    > ---
    > drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 181 +++++++++++++++------
    > 1 file changed, 132 insertions(+), 49 deletions(-)
    >
    > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    > index 846574d0dcb0..501f7b4a23d6 100644
    > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    > @@ -160,80 +160,135 @@ 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 < 0)
    > + 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 < 0)

    Above we check for ret != 1, so we should probably stay consistent. Same nit
    throughout the patch.

    > + 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 retval;

    Above we're replacing retval with ret, however here we introduce retval.

    > +
    > analogix_dp_set_training_pattern(dp, DP_NONE);
    >
    > - drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
    > - DP_TRAINING_PATTERN_DISABLE);
    > + retval = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET,
    > + DP_TRAINING_PATTERN_DISABLE);
    > +
    > + return retval < 0 ? retval : 0;
    > }
    >
    > static void
    > @@ -282,7 +337,11 @@ 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 +626,11 @@ 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",
    > @@ -807,7 +867,6 @@ static int analogix_dp_train_link(struct analogix_dp_device *dp)
    >
    > static int analogix_dp_config_video(struct analogix_dp_device *dp)
    > {
    > - int retval = 0;
    > int timeout_loop = 0;
    > int done_count = 0;
    >
    > @@ -825,8 +884,9 @@ static int analogix_dp_config_video(struct analogix_dp_device *dp)
    > if (analogix_dp_is_slave_video_stream_clock_on(dp) == 0)
    > break;
    > if (timeout_loop > DP_TIMEOUT_LOOP_COUNT) {
    > - dev_err(dp->dev, "Timeout of slave video streamclk ok\n");
    > - return -ETIMEDOUT;
    > + dev_warn(dp->dev,
    > + "Ignoring timeout of slave video streamclk ok\n");
    > + break;

    This change has sort of snuck in here. It doesn't seem related to the change,
    but maybe I'm overlooking something.

    > }
    > usleep_range(1000, 1001);

    Unrelated: This is pretty hilarious.

    > }
    > @@ -865,30 +925,38 @@ static int analogix_dp_config_video(struct analogix_dp_device *dp)
    > usleep_range(1000, 1001);
    > }
    >
    > - if (retval != 0)
    > - dev_err(dp->dev, "Video stream is not detected!\n");
    > -
    > - return retval;
    > + 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));

    This should probably be explicitly checked as well, since the inline conditional
    in the return isn't checking what the rest of the function is.

    > }
    > +
    > + return ret < 0 ? ret : 0;
    > }
    >
    > static irqreturn_t analogix_dp_hardirq(int irq, void *arg)
    > @@ -943,23 +1011,36 @@ 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;
    > }
    >
    > /*
    > @@ -1186,8 +1267,10 @@ 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;
    > --
    > 2.14.1
    >

    --
    Sean Paul, Software Engineer, Google / Chromium OS

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