[PATCH 5.4 67/76] drm/i915/dsi: Use unconditional msleep for the panel_on_delay when there is no reset-deassert MIPI-sequence

From: Greg Kroah-Hartman
Date: Mon Jan 18 2021 - 13:57:54 EST

From: Hans de Goede <hdegoede@xxxxxxxxxx>

commit 00cb645fd7e29bdd20967cd20fa8f77bcdf422f9 upstream.

Commit 25b4620ee822 ("drm/i915/dsi: Skip delays for v3 VBTs in vid-mode")
added an intel_dsi_msleep() helper which skips sleeping if the
MIPI-sequences have a version of 3 or newer and the panel is in vid-mode;
and it moved a bunch of msleep-s over to this new helper.

This was based on my reading of the big comment around line 730 which
starts with "Panel enable/disable sequences from the VBT spec.",
where the "v3 video mode seq" column does not have any wait t# entries.

Given that this code has been used on a lot of different devices without
issues until now, it seems that my interpretation of the spec here is
mostly correct.

But now I have encountered one device, an Acer Aspire Switch 10 E
SW3-016, where the panel will not light up unless we do actually honor the
panel_on_delay after exexuting the MIPI_SEQ_PANEL_ON sequence.

What seems to set this model apart is that it is lacking a
MIPI_SEQ_DEASSERT_RESET sequence, which is where the power-on
delay usually happens.

Fix the panel not lighting up on this model by using an unconditional
msleep(panel_on_delay) instead of intel_dsi_msleep() when there is

Fixes: 25b4620ee822 ("drm/i915/dsi: Skip delays for v3 VBTs in vid-mode")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20201118124058.26021-1-hdegoede@xxxxxxxxxx
(cherry picked from commit 6fdb335f1c9c0845b50625de1624d8445c4c4a07)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/gpu/drm/i915/display/vlv_dsi.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/display/vlv_dsi.c
+++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
@@ -797,10 +797,20 @@ static void intel_dsi_pre_enable(struct
if (intel_dsi->gpio_panel)
gpiod_set_value_cansleep(intel_dsi->gpio_panel, 1);
intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_POWER_ON);
- intel_dsi_msleep(intel_dsi, intel_dsi->panel_on_delay);

- /* Deassert reset */
- intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);
+ /*
+ * Give the panel time to power-on and then deassert its reset.
+ * Depending on the VBT MIPI sequences version the deassert-seq
+ * may contain the necessary delay, intel_dsi_msleep() will skip
+ * the delay in that case. If there is no deassert-seq, then an
+ * unconditional msleep is used to give the panel time to power-on.
+ */
+ if (dev_priv->vbt.dsi.sequence[MIPI_SEQ_DEASSERT_RESET]) {
+ intel_dsi_msleep(intel_dsi, intel_dsi->panel_on_delay);
+ intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);
+ } else {
+ msleep(intel_dsi->panel_on_delay);
+ }

if (IS_GEMINILAKE(dev_priv)) {
glk_cold_boot = glk_dsi_enable_io(encoder);