[PATCH 2/5] clk: mediatek: clk-mt8188-topckgen: Remove univpll from parents of mfg_core_tmp

Pablo Sun
2024-09-20T13:42:32Z

Same as MT8195, MT8188 GPU clock is primarly supplied by the dedicated
mfgpll. The clock "mfg_core_tmp" is only used as an alt clock when
setting mfgpll clock rate.

If we keep the univpll parents from mfg_core_tmp, when setting
GPU frequency to 390000000, the common clock framework would switch
the parent to univpll, instead of setting mfgpll to 390000000:

mfgpll 0 0 0 949999756
univpll 2 2 0 2340000000
univpll_d6 1 1 0 390000000
top_mfg_core_tmp 1 1 0 390000000
mfg_ck_fast_ref 1 1 0 390000000
mfgcfg_bg3d 1 1 0 390000000

This results in failures when subsequent devfreq operations need to
switch to other frequencies. So remove univpll from the parent list.

This solution is taken from commit 72d38ed720e9 ("clk: mediatek:
clk-mt8195-topckgen: Drop univplls from mfg mux parents")

Signed-off-by: Pablo Sun <pablo.sun@mediatek.com>
---
drivers/clk/mediatek/clk-mt8188-topckgen.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/mediatek/clk-mt8188-topckgen.c b/drivers/clk/mediatek/clk-mt8188-topckgen.c
index 2ccc8a1c98f9..74ee692ac613 100644
--- a/drivers/clk/mediatek/clk-mt8188-topckgen.c
+++ b/drivers/clk/mediatek/clk-mt8188-topckgen.c
@@ -342,11 +342,14 @@ static const char * const dsp7_parents[] = {
"univpll_d3"
};

+/*
+ * MFG can be also parented to "univpll_d6" and "univpll_d7":
+ * these have been removed from the parents list to let us
+ * achieve GPU DVFS without any special clock handlers.
+ */
static const char * const mfg_core_tmp_parents[] = {
"clk26m",
"mainpll_d5_d2",
- "univpll_d6",
- "univpll_d7"
};

static const char * const camtg_parents[] = {
--
2.45.2