Quoting Geert Uytterhoeven (2021-03-26 05:00:59)

+}
+
+static int cpg_pll_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+                               unsigned long parent_rate)
+{
+       struct cpg_pll_clk *pll_clk = to_pll_clk(hw);
+       unsigned int mult, i;
+       u32 val;
+
+       mult = DIV_ROUND_CLOSEST_ULL(rate, parent_rate * pll_clk->fixed_mult);
+       mult = clamp(mult, 1U, 128U);
+
+       val = readl(pll_clk->pllcr_reg);
+       val &= ~CPG_PLLnCR_STC_MASK;
+       val |= (mult - 1) << __ffs(CPG_PLLnCR_STC_MASK);
+       writel(val, pll_clk->pllcr_reg);
+
+       for (i = 1000; i; i--) {
+               if (readl(pll_clk->pllecr_reg) & pll_clk->pllecr_pllst_mask)
+                       return 0;
+
+               cpu_relax();
+       }

Why not readl_poll_timeout()?

+
+       return -ETIMEDOUT;
+}
+