5.15-stable review patch. If anyone has any objections, please let me know.
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From: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org
[ Upstream commit 5ddcb0cb9d10e6e70a68e0cb8f0b8e3a7eb8ccaf ]
Driver unconditionally saves current state on first init in dsi_pll_7nm_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_7nm_pll_restore_state().
Restoring calls dsi_pll_7nm_vco_set_rate() with pll_7nm->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.
Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@oss.qualcomm.com Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Patchwork: https://patchwork.freedesktop.org/patch/657827/ Link: https://lore.kernel.org/r/20250610-b4-sm8750-display-v6-9-ee633e3ddbff@linar... Signed-off-by: Dmitry Baryshkov dmitry.baryshkov@oss.qualcomm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c index 10d5b9cf98df5..a5f51534e6e96 100644 --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c @@ -760,6 +760,12 @@ static int dsi_pll_7nm_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_7nm_pll_restore_state(). + */ + if (!dsi_pll_7nm_vco_recalc_rate(&pll_7nm->clk_hw, VCO_REF_CLK_RATE)) + pll_7nm->vco_current_rate = pll_7nm->phy->cfg->min_pll_rate;
return 0; }