Hi,
On 11/24/20 4:49 PM, Ville Syrjälä wrote:
On Wed, Nov 18, 2020 at 01:40:58PM +0100, Hans de Goede wrote:
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 no MIPI_SEQ_DEASSERT_RESET sequence.
Fixes: 25b4620ee822 ("drm/i915/dsi: Skip delays for v3 VBTs in vid-mode") Signed-off-by: Hans de Goede hdegoede@redhat.com
drivers/gpu/drm/i915/display/vlv_dsi.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c index 194c239ab6b1..ef673277b36d 100644 --- a/drivers/gpu/drm/i915/display/vlv_dsi.c +++ b/drivers/gpu/drm/i915/display/vlv_dsi.c @@ -816,10 +816,14 @@ static void intel_dsi_pre_enable(struct intel_atomic_state *state, intel_dsi_prepare(encoder, pipe_config);
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);
- if (dev_priv->vbt.dsi.sequence[MIPI_SEQ_DEASSERT_RESET]) {
intel_dsi_msleep(intel_dsi, intel_dsi->panel_on_delay);/* Deassert reset */intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);- } else {
msleep(intel_dsi->panel_on_delay);- }
Could perhaps use a comment ot explain to the reader what's going on.
Looks sane enough to me, and if we get this wrong we just get a bigger delay than necessary I guess. So mostly harmless.
Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com
Thank you, and sorry for being slow with getting around to pushing this to drm-intel-next.
I've just pushed it to drm-intel-next with a comment added above the if (and dropped the single line comment inside the if), so this now looks like this:
/* * 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); }
(the code is unchanged from when you reviewed it).
Regards,
Hans