This series adds a clock notifier for MediaTek clock muxes, required in order to achieve stability for GPU DVFS. The GPU frequency scaling mechanism requires us to switch the GPU mux clock to a safe parent which frequency is always less or equal to the "current" GPU frequency before reprogramming its dedicated "MFG" PLL. This is needed because the PLL needs time to reconfigure for its output to stabilize (so, for the PLL to lock again): failing to do so will lead to instabilities such as glitches, GPU lockups and/or full system lockups. While at it, reparenting of some GPU clocks was also performed, as the clock tree was slightly incorrect. This series was tested, along with mtk-regulator-coupler [1], on Chromebooks with different SoCs (MT8183, MT8192, MT8195*), resulting in fully working GPU DVFS with the Panfrost driver. [1]: https://patchwork.kernel.org/project/linux-mediatek/patch/20220628120224.81180-1-angelogioacchino.delregno@xxxxxxxxxxxxx/ * MT8195 does not require mtk-regulator-coupler. This series, along with [1], are required to perform GPU DVFS also on non-Chromebook SoCs. Changes in v2: - Added comment in clk-mt8195-topckgen to keep the mfg parents documented after removal, as suggested by Chen-Yu AngeloGioacchino Del Regno (6): clk: mediatek: clk-mt8195-mfg: Reparent mfg_bg3d and propagate rate changes clk: mediatek: clk-mt8195-topckgen: Register mfg_ck_fast_ref as generic mux clk: mediatek: clk-mt8195-topckgen: Add GPU clock mux notifier clk: mediatek: clk-mt8195-topckgen: Drop univplls from mfg mux parents clk: mediatek: clk-mt8192-mfg: Propagate rate changes to parent clk: mediatek: clk-mt8192: Add clock mux notifier for mfg_pll_sel Chen-Yu Tsai (4): arm64: dts: mt8183: Fix Mali GPU clock clk: mediatek: mt8183: mfgcfg: Propagate rate changes to parent clk: mediatek: mux: add clk notifier functions clk: mediatek: mt8183: Add clk mux notifier for MFG mux arch/arm64/boot/dts/mediatek/mt8183.dtsi | 2 +- drivers/clk/mediatek/clk-mt8183-mfgcfg.c | 6 +-- drivers/clk/mediatek/clk-mt8183.c | 28 +++++++++++++ drivers/clk/mediatek/clk-mt8192-mfg.c | 6 ++- drivers/clk/mediatek/clk-mt8192.c | 28 +++++++++++++ drivers/clk/mediatek/clk-mt8195-mfg.c | 6 ++- drivers/clk/mediatek/clk-mt8195-topckgen.c | 46 +++++++++++++++------- drivers/clk/mediatek/clk-mux.c | 38 ++++++++++++++++++ drivers/clk/mediatek/clk-mux.h | 15 +++++++ 9 files changed, 153 insertions(+), 22 deletions(-) -- 2.37.2
