drm/i915/dsi: Use a fuzzy check for burst mode clock check (f9a99131) · Commits · 戴 / test

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@vger.kernel.org Reviewed-by:

Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by:

Hans de Goede <hdegoede@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190524174028.21659-2-hdegoede@redhat.com (cherry picked from commit ) Signed-off-by:

Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -11942,7 +11942,7 @@ 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;

drivers/gpu/drm/i915/intel_drv.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -1742,6 +1742,7 @@ 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,

drivers/gpu/drm/i915/intel_dsi_vbt.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -853,6 +853,17 @@ 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;

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