From: Hans de Goede <hdegoede@xxxxxxxxxx> Prior to this commit we fail to init the DSI panel on the GPD MicroPC: https://www.indiegogo.com/projects/gpd-micropc-6-inch-handheld-industry-laptop#/ The problem is intel_dsi_vbt_init() failing with the following error: *ERROR* Burst mode freq is less than computed The pclk in the VBT panel modeline is 70000, together with 24 bpp and 4 lines this results in a bitrate value of 70000 * 24 / 4 = 420000. But the target_burst_mode_freq in the VBT is 418000. This commit works around this problem by adding an intel_fuzzy_clock_check when target_burst_mode_freq < bitrate and setting target_burst_mode_freq to bitrate when that checks succeeds, fixing the panel not working. Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20190524174028.21659-2-hdegoede@xxxxxxxxxx --- drivers/gpu/drm/i915/intel_display.c | 2 +- drivers/gpu/drm/i915/intel_drv.h | 1 + drivers/gpu/drm/i915/intel_dsi_vbt.c | 11 +++++++++++ 3 files changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 122a075b6174..1560030563b6 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12163,7 +12163,7 @@ intel_modeset_pipe_config(struct intel_crtc_state *pipe_config) return 0; } -static bool intel_fuzzy_clock_check(int clock1, int clock2) +bool intel_fuzzy_clock_check(int clock1, int clock2) { int diff; diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 0dcc03592d6e..d0aeb383024a 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1557,6 +1557,7 @@ int vlv_force_pll_on(struct drm_i915_private *dev_priv, enum pipe pipe, const struct dpll *dpll); void vlv_force_pll_off(struct drm_i915_private *dev_priv, enum pipe pipe); int lpt_get_iclkip(struct drm_i915_private *dev_priv); +bool intel_fuzzy_clock_check(int clock1, int clock2); /* modesetting asserts */ void assert_panel_unlocked(struct drm_i915_private *dev_priv, diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c index fbed9064ac7e..7cdde1d04f4b 100644 --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c @@ -858,6 +858,17 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id) if (mipi_config->target_burst_mode_freq) { u32 bitrate = intel_dsi_bitrate(intel_dsi); + /* + * Sometimes the VBT contains a slightly lower clock, + * then the bitrate we have calculated, in this case + * just replace it with the calculated bitrate. + */ + if (mipi_config->target_burst_mode_freq < bitrate && + intel_fuzzy_clock_check( + mipi_config->target_burst_mode_freq, + bitrate)) + mipi_config->target_burst_mode_freq = bitrate; + if (mipi_config->target_burst_mode_freq < bitrate) { DRM_ERROR("Burst mode freq is less than computed\n"); return false;
