Thread (26 messages) 26 messages, 5 authors, 2012-11-12

Re: [PATCH 5/8] ARM: zynq: add COMMON_CLK support

From: Josh Cartwright <hidden>
Date: 2012-11-02 13:40:58
Also in: linux-arm-kernel, linux-serial, lkml

Thanks for the review.

On Fri, Nov 02, 2012 at 10:33:44AM +0100, Lars-Peter Clausen wrote:
On 10/31/2012 07:58 PM, Josh Cartwright wrote:
quoted
[...]
+#define PERIPH_CLK_CTRL_SRC(x)	(periph_clk_parent_map[((x)&3)>>4])
+#define PERIPH_CLK_CTRL_DIV(x)	(((x)&0x3F00)>>8)
A few more spaces wouldn't hurt ;)
Okay, sure.
quoted
[...]
+static void __init zynq_periph_clk_setup(struct device_node *np)
+{
+	struct zynq_periph_clk *periph;
+	const char *parent_names[3];
+	struct clk_init_data init;
+	struct clk *clk;
+	int err;
+	u32 reg;
+	int i;
+
+	err = of_property_read_u32(np, "reg", &reg);
+	WARN_ON(err);
Shouldn't the function abort if a error happens somewhere? Continuing here
will lead to undefined behavior. Same is probably true for the other WARN_ONs.
The way I see it is: the kernel is will be left in a bad state in the
case of any failure, regardless of if we bail out or continue.  AFAICT,
there is no clean way to recover from a failure this early.

Given that, it seems simpler (albeit marginally so) just to continue; so
that's what I chose to do.  I'm not opposed to bailing out, just not
convinced it does anything for us.
quoted
+
+	periph = kzalloc(sizeof(*periph), GFP_KERNEL);
+	WARN_ON(!periph);
+
+	periph->clk_ctrl = slcr_base + reg;
+	spin_lock_init(&periph->clkact_lock);
+
+	init.name = np->name;
+	init.ops = &zynq_periph_clk_ops;
+	for (i = 0; i < ARRAY_SIZE(parent_names); i++)
+		parent_names[i] = of_clk_get_parent_name(np, i);
+	init.parent_names = parent_names;
+	init.num_parents = ARRAY_SIZE(parent_names);
+
+	periph->hw.init = &init;
+
+	clk = clk_register(NULL, &periph->hw);
+	WARN_ON(IS_ERR(clk));
+
+	err = of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	WARN_ON(err);
+
+	for (i = 0; i < 2; i++) {
Not all of the peripheral clock generators have two output clocks. I think
it makes sense to use the number entries in clock-output-names here.
Yes, I agree.  I'll also update the bindings documentation.

Thanks again,
  Josh
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