From: Hans de Goede <hdegoede@xxxxxxxxxx> commit f9a99131ce18d9dddcaa14ec2c436e42f0bbee5e upstream. 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 (cherry picked from commit 2c1c55252647abd989b94f725b190c700312d053) Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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(-) --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -11757,7 +11757,7 @@ encoder_retry: return 0; } -static bool intel_fuzzy_clock_check(int clock1, int clock2) +bool intel_fuzzy_clock_check(int clock1, int clock2) { int diff; --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1707,6 +1707,7 @@ int vlv_force_pll_on(struct drm_i915_pri 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, --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c @@ -871,6 +871,17 @@ bool intel_dsi_vbt_init(struct intel_dsi 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;
