Driver unconditionally saves current state on first init in dsi_pll_10nm_init(), but does not save the VCO rate, only some of the divider registers. The state is then restored during probe/enable via msm_dsi_phy_enable() -> msm_dsi_phy_pll_restore_state() -> dsi_10nm_pll_restore_state().
Restoring calls dsi_pll_10nm_vco_set_rate() with pll_10nm->vco_current_rate=0, which basically overwrites existing rate of VCO and messes with clock hierarchy, by setting frequency to 0 to clock tree. This makes anyway little sense - VCO rate was not saved, so should not be restored. If PLL was not configured configure it to minimum rate to avoid glitches and configuring entire in clock hierarchy to 0 Hz. Suggested-by: Dmitry Baryshkov <dmitry.barysh...@oss.qualcomm.com> Link: https://lore.kernel.org/r/sz4kbwy5nwsebgf64ia7uq4ee7wbsa5uy3xmlqwcstsbntzcov@ew3dcyjdzmi2/ Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlow...@linaro.org> --- Not tested on hardware. --- drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c index 9812b4d69197..af2e30f3f842 100644 --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c @@ -704,6 +704,13 @@ static int dsi_pll_10nm_init(struct msm_dsi_phy *phy) /* TODO: Remove this when we have proper display handover support */ msm_dsi_phy_pll_save_state(phy); + /* + * Store also proper vco_current_rate, because its value will be used in + * dsi_10nm_pll_restore_state(). + */ + if (!dsi_pll_10nm_vco_recalc_rate(&pll_10nm->clk_hw, VCO_REF_CLK_RATE)) + pll_10nm->vco_current_rate = pll_10nm->phy->cfg->min_pll_rate; + return 0; } -- 2.45.2
