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    SubjectRe: [PATCH v2 29/43] drm/bridge: analogix_dp: Move fast link training detect to set_bridge
    On Fri, Jan 26, 2018 at 02:16:56PM +0100, Thierry Escande wrote:
    > From: zain wang <wzz@rock-chips.com>
    >
    > It's too early to detect fast link training, if other step after it
    > failed, we will set fast_link flag to 1, and retry set_bridge again. In
    > this case we will power down and power up panel power supply, and we
    > will do fast link training since we have set fast_link flag to 1. In
    > fact, we should do full link training now, not the fast link training.
    > So we should move the fast link detection at the end of set_bridge.
    >
    > Cc: Tomasz Figa <tfiga@chromium.org>
    > 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 | 42 +++++++++++++---------
    > 1 file changed, 26 insertions(+), 16 deletions(-)
    >
    > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    > index e7ab871e62b5..bee0f7aa5c23 100644
    > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    > @@ -599,7 +599,7 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
    > {
    > int lane, lane_count, retval;
    > u32 reg;
    > - u8 link_align, link_status[2], adjust_request[2], spread;
    > + u8 link_align, link_status[2], adjust_request[2];
    >
    > usleep_range(400, 401);
    >
    > @@ -643,20 +643,6 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
    > dev_dbg(dp->dev, "final lane count = %.2x\n",
    > dp->link_train.lane_count);
    >
    > - retval = drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD,
    > - &spread);
    > - if (retval != 1) {
    > - dev_err(dp->dev, "failed to read downspread %d\n",
    > - retval);
    > - dp->fast_train_enable = false;
    > - } else {
    > - dp->fast_train_enable =
    > - (spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING) ?
    > - true : false;
    > - }
    > - dev_dbg(dp->dev, "fast link training %s\n",
    > - dp->fast_train_enable ? "supported" : "unsupported");
    > -
    > dp->link_train.lt_state = FINISHED;
    >
    > return 0;
    > @@ -997,6 +983,22 @@ static irqreturn_t analogix_dp_irq_thread(int irq, void *arg)
    > return IRQ_HANDLED;
    > }
    >
    > +static int analogix_dp_fast_link_train_detection(struct analogix_dp_device *dp)
    > +{
    > + int ret;
    > + u8 spread;
    > +
    > + ret = drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD, &spread);
    > + if (ret != 1) {
    > + dev_err(dp->dev, "failed to read downspread %d\n", ret);
    > + return ret;
    > + }
    > + dp->fast_train_enable = !!(spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING);
    > + dev_dbg(dp->dev, "fast link training %s\n",
    > + dp->fast_train_enable ? "supported" : "unsupported");
    > + return 0;
    > +}
    > +
    > static int analogix_dp_commit(struct analogix_dp_device *dp)
    > {
    > int ret;
    > @@ -1039,8 +1041,16 @@ static int analogix_dp_commit(struct analogix_dp_device *dp)
    > if (ret)
    > return ret;
    >
    > - if (dp->psr_enable)
    > + if (dp->psr_enable) {
    > ret = analogix_dp_enable_sink_psr(dp);
    > + if (ret)
    > + return ret;
    > + }
    > +
    > + /* Check whether panel supports fast training */
    > + ret = analogix_dp_fast_link_train_detection(dp);
    > + if (ret)
    > + dp->psr_enable = false;

    You could probably flip this with psr_enable and just return on error instead of
    flipping psr_enable back. Not a big deal either way.

    Sean

    >
    > return ret;
    > }
    > --
    > 2.14.1
    >

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

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