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 Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/gpu/drm/i915/intel_dsi_vbt.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c index 022bf59418df..a2a9b9d0eeaa 100644 --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c @@ -895,6 +895,17 @@ 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; -- 2.21.0
