drm/bridge: tc358767: fix poll timeouts

Link training fails with:

  Link training timeout waiting for LT_LOOPDONE!
  main link enable error: -110

This is caused by too tight timeouts, which were changed recently in
aa92213f388b ("drm/bridge: tc358767: Simplify polling in tc_link_training()").

With a quick glance, the commit does not change the timeouts. However,
the method of delaying/sleeping is different, and as the timeout in the
previous implementation was not explicit, the new version in practice
has much tighter timeout.

The same change was made to other parts in the driver, but the link
training timeout is the only one I have seen causing issues.
Nevertheless, 1 us sleep is not very sane, and the timeouts look pretty
tight, so lets fix all the timeouts.

One exception was the aux busy poll, where the poll sleep was much
longer than necessary (or optimal).

I measured the times on my setup, and now the sleep times are set to
such values that they result in multiple loops, but not too many (say,
5-10 loops). The timeouts were all increased to 100ms, which should be
more than enough for all of these, but in case of bad errors, shouldn't
stop the driver as multi-second timeouts could do.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Fixes: aa92213f388b ("drm/bridge: tc358767: Simplify polling in tc_link_training()")
Tested-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191209082707.24531-1-tomi.valkeinen@ti.com

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index 8029478ffebbc6eab05591322782014c6865eb39..b0b0ccbb059d6425b99d13fe21c9243f410dd8aa 100644 (file)
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -297,7 +297,7 @@ static inline int tc_poll_timeout(struct tc_data *tc, unsigned int addr,
 
 static int tc_aux_wait_busy(struct tc_data *tc)
 {
-       return tc_poll_timeout(tc, DP0_AUXSTATUS, AUX_BUSY, 0, 1000, 100000);
+       return tc_poll_timeout(tc, DP0_AUXSTATUS, AUX_BUSY, 0, 100, 100000);
 }
 
 static int tc_aux_write_data(struct tc_data *tc, const void *data,
@@ -640,7 +640,7 @@ static int tc_aux_link_setup(struct tc_data *tc)
        if (ret)
                goto err;
 
-       ret = tc_poll_timeout(tc, DP_PHY_CTRL, PHY_RDY, PHY_RDY, 1, 1000);
+       ret = tc_poll_timeout(tc, DP_PHY_CTRL, PHY_RDY, PHY_RDY, 100, 100000);
        if (ret == -ETIMEDOUT) {
                dev_err(tc->dev, "Timeout waiting for PHY to become ready");
                return ret;
@@ -876,7 +876,7 @@ static int tc_wait_link_training(struct tc_data *tc)
        int ret;
 
        ret = tc_poll_timeout(tc, DP0_LTSTAT, LT_LOOPDONE,
-                             LT_LOOPDONE, 1, 1000);
+                             LT_LOOPDONE, 500, 100000);
        if (ret) {
                dev_err(tc->dev, "Link training timeout waiting for LT_LOOPDONE!\n");
                return ret;
@@ -949,7 +949,7 @@ static int tc_main_link_enable(struct tc_data *tc)
        dp_phy_ctrl &= ~(DP_PHY_RST | PHY_M1_RST | PHY_M0_RST);
        ret = regmap_write(tc->regmap, DP_PHY_CTRL, dp_phy_ctrl);
 
-       ret = tc_poll_timeout(tc, DP_PHY_CTRL, PHY_RDY, PHY_RDY, 1, 1000);
+       ret = tc_poll_timeout(tc, DP_PHY_CTRL, PHY_RDY, PHY_RDY, 500, 100000);
        if (ret) {
                dev_err(dev, "timeout waiting for phy become ready");
                return ret;