diff options
| author | Sean Paul <seanpaul@chromium.org> | 2018-08-13 17:30:46 -0400 |
|---|---|---|
| committer | Sean Paul <seanpaul@chromium.org> | 2018-08-27 10:57:20 -0400 |
| commit | bf1178c9893018b77c829215970cf4c6a3cebb34 (patch) | |
| tree | cd49a18ddd4e29c80f8a81eee4e555aa7192f1d8 /drivers/gpu/drm/bridge/ti-sn65dsi86.c | |
| parent | bc537a9cc47eec7f4e32b8164c494ddc35dca8ac (diff) | |
drm/bridge: ti-sn65dsi86: Add mystery delay to enable()
This patch adds a 70ms mystery delay to the bridge driver in enable.
By experimentation, it seems like it can go anywhere up until we
initiate semi-auto link training. If we don't have the delay, link
training fails.
I tried to root cause this as best I could, but neither the datasheet
for the panel nor the bridge mention a delay of this magnitude in their
timing requirements. So for now, add the mystery delay until someone
figures out a better fix.
Changes in v3:
- Added to the set
Cc: Sandeep Panda <spanda@codeaurora.org>
Reviewed-by: Sandeep Panda <spanda@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180813213058.184821-8-sean@poorly.run
Diffstat (limited to 'drivers/gpu/drm/bridge/ti-sn65dsi86.c')
| -rw-r--r-- | drivers/gpu/drm/bridge/ti-sn65dsi86.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index d3e27e52ea75..f8a931cf3665 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -458,6 +458,18 @@ static void ti_sn_bridge_enable(struct drm_bridge *bridge) unsigned int val; int ret; + /* + * FIXME: + * This 70ms was found necessary by experimentation. If it's not + * present, link training fails. It seems like it can go anywhere from + * pre_enable() up to semi-auto link training initiation below. + * + * Neither the datasheet for the bridge nor the panel tested mention a + * delay of this magnitude in the timing requirements. So for now, add + * the mystery delay until someone figures out a better fix. + */ + msleep(70); + /* DSI_A lane config */ val = CHA_DSI_LANES(4 - pdata->dsi->lanes); regmap_update_bits(pdata->regmap, SN_DSI_LANES_REG, |