Hi Stephen,

On Thu, 1 Oct 2015 15:32:20 -0700
Stephen Boyd [off-list ref] wrote:

On 09/22, Jisheng Zhang wrote:

quoted

diff --git a/drivers/clk/berlin/pll.c b/drivers/clk/berlin/pll.c
new file mode 100644
index 0000000..9aad0b6
--- /dev/null
+++ b/drivers/clk/berlin/pll.c

@@ -0,0 +1,119 @@
+
+#define to_berlin_pll(hw)       container_of(hw, struct berlin_pll, hw)
+
+static u8 vcodiv_berlin[] = {1, 2, 4, 8, 16, 32, 64, 128};

This is an array of 1 << index position...

oops, yes! I didn't realize this before! Accept all the comments below, will
update in v2.

Thanks a lot for review,
Jisheng

quoted

+
+static unsigned long berlin_pll_recalc_rate(struct clk_hw *hw,
+					    unsigned long parent_rate)
+{
+	u32 val, fbdiv, rfdiv, vcodivsel, bypass;
+	struct berlin_pll *pll = to_berlin_pll(hw);
+
+	bypass = readl_relaxed(pll->bypass);
+	if (bypass & (1 << pll->bypass_shift))
+		return parent_rate;
+
+	val = readl_relaxed(pll->ctrl + PLL_CTRL0);
+	fbdiv = (val >> 12) & 0x1FF;
+	rfdiv = (val >> 3) & 0x1FF;
+	val = readl_relaxed(pll->ctrl + PLL_CTRL1);
+	vcodivsel = (val >> 9) & 0x7;
+	return parent_rate * fbdiv * 4 / rfdiv /
+		vcodiv_berlin[vcodivsel];

so we can replace this with 1 << vcodivsel?

quoted

+}
+
+static u8 berlin_pll_get_parent(struct clk_hw *hw)
+{
+	struct berlin_pll *pll = to_berlin_pll(hw);
+	u32 bypass = readl_relaxed(pll->bypass);
+
+	if (bypass & (1 << pll->bypass_shift))
+		return 1;
+	else
+		return 0;

Simplify this to 

	if (bypass & (1 << pll->bypass_shift))
		return 1;
	return 0;

or

	return !!(bypass & (1 << pll->bypass_shift)) 

quoted

+}
+
+static const struct clk_ops berlin_pll_ops = {
+	.recalc_rate	= berlin_pll_recalc_rate,
+	.get_parent	= berlin_pll_get_parent,
+};
+
+void __init berlin_pll_setup(struct device_node *np)

static?

quoted

+{
+	struct clk_init_data init;
+	struct berlin_pll *pll;
+	const char *parent_names[PLL_SOURCE_MAX];
+	struct clk *clk;
+	int ret, num_parents;
+
+	num_parents = of_clk_get_parent_count(np);
+	if (num_parents <= 0 || num_parents > PLL_SOURCE_MAX)
+		return;
+
+	of_clk_parent_fill(np, parent_names, num_parents);
+
+	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+	if (WARN_ON(!pll))

We already print a big warning on allocation failures, so drop
the WARN_ON please.

quoted

+		return;
+
+	pll->ctrl = of_iomap(np, 0);
+	pll->bypass = of_iomap(np, 1);
+	ret = of_property_read_u8(np, "bypass-shift", &pll->bypass_shift);
+	if (WARN_ON(!pll->ctrl || !pll->bypass || ret))
+		return;
+
+	init.name = np->name;
+	init.ops = &berlin_pll_ops;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;

init.flags is not initialized. Please initialize the init struct
on the stack to 0 to avoid future problems.

quoted

+
+	pll->hw.init = &init;
+
+	clk = clk_register(NULL, &pll->hw);
+	if (WARN_ON(IS_ERR(clk)))
+		return;
+
+	ret = of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	if (WARN_ON(ret))
+		return;

This return is useless.

quoted

+}