On Wed, 17 Oct 2018, Hans de Goede <j.w.r.degoede@xxxxxxxxx> wrote: > On BYT and CHT the GOP sometimes initializes the pclk at a (slightly) > different frequency then the pclk which we've calculated. > > This commit makes the DSI code read-back the pclk set by the GOP and > if that is within a reasonable margin of the calculated pclk, uses > that instead. > > This fixes the first modeset being a full modeset instead of a > fast modeset on systems where the GOP pclk is different. I assume we don't do the fast path because intel_pipe_config_compare() returns false due to crtc_clock and port_clock mismatch. The dmesg should tell you the reason with drm.debugs enabled. Now, the clock checks are already "fuzzy", and should account for slight variations. I think the goal was the same as here, plus IIUC we may lose some accuracy on the hardware roundtrip. Please try adding more tolerance in intel_fuzzy_clock_check() and see if that helps. The code looks like it allows 5% diff, but it's 2.5%. Regardless of whether we end up changing the tolerance or adjusting the state based on the hardware readout or what, I think doing the adjustment in intel_dsi_vbt.c init is the wrong place. We shouldn't have anything that depends on accessing the hardware there. I believe that's what Ville was trying to say in [1]. BR, Jani. [1] http://mid.mail-archive.com/20180706141652.GK5565@xxxxxxxxx > > Changes in v2: > -Use intel_encoder_current_mode() to get the pclk setup by the GOP > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_dsi_vbt.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c > index ac83d6b89ae0..3387b187105c 100644 > --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c > +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c > @@ -506,6 +506,7 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id) > struct mipi_config *mipi_config = dev_priv->vbt.dsi.config; > struct mipi_pps_data *pps = dev_priv->vbt.dsi.pps; > struct drm_display_mode *mode = dev_priv->vbt.lfp_lvds_vbt_mode; > + struct drm_display_mode *curr; > u32 bpp; > u32 tlpx_ns, extra_byte_count, bitrate, tlpx_ui; > u32 ui_num, ui_den; > @@ -583,6 +584,23 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id) > } else > burst_mode_ratio = 100; > > + /* > + * On BYT / CRC the GOP sometimes picks a slightly different pclk, > + * read back the GOP configured pclk and prefer it over ours. > + */ > + if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) { > + curr = intel_encoder_current_mode(&intel_dsi->base); > + if (curr) { > + DRM_DEBUG_KMS("Calculated pclk %d GOP %d\n", > + pclk, curr->clock); > + if (curr->clock >= (pclk * 9 / 10) && > + curr->clock <= (pclk * 11 / 10)) > + pclk = curr->clock; > + > + kfree(curr); > + } > + } > + > intel_dsi->burst_mode_ratio = burst_mode_ratio; > intel_dsi->pclk = pclk; -- Jani Nikula, Intel Open Source Graphics Center _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
