Re: [PATCH v7] clk: add si5351 i2c common clock driver

From: Sebastian Hesselbarth
Date: Wed Apr 10 2013 - 13:27:36 EST


Hooray Google!

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On 04/10/2013 04:48 PM, Michal Bachraty wrote:
Hi Sebastian,
This driver doesn't work for me. In my case, u-boot initializes si-5351 and
power down unused clocks while booting kernel. there is need for power up
clocks as was in previous versions of your driver.
See patch, whre the problem is fixed:

@@ -992,6 +992,10 @@ static long si5351_clkout_round_rate(struct clk_hw *hw,
unsigned long rate,
} while (1);
}
rate = *parent_rate>> rdiv;
+
+ /* powerup clkout */
+ si5351_set_bits(hwdata->drvdata, SI5351_CLK0_CTRL + hwdata->num,
+ SI5351_CLK_POWERDOWN, 0);

dev_dbg(&hwdata->drvdata->client->dev,
"%s - %s: rdiv = %u, parent_rate = %lu, rate = %lu\n",

With this lines, driver works well.

Hmm, is there any driver using the clock output? Does it clk_prepare_enable() the clock?
I tend not to mess with anything the bootloader or eeprom config left disabled. It works
for me, but here the driver will prepare/enable the clock prior use.

Also,

+==Example==
+
+/* 25MHz reference crystal */
+ref25: ref25M {
+ compatible = "fixed-clock";
+ #clock-cells =<0>;
+ clock-frequency =<25000000>;
+};
+
+i2c-master-node {
+
+ /* Si5351a msop10 i2c clock generator */
+ si5351a: clock-generator@60 {
+ compatible = "silabs,si5351a-msop";
+ reg =<0x60>;
+ #address-cells =<1>;
+ #size-cells =<0>;
+ #clock-cells =<1>;
+
+ /* connect xtal input to 25MHz reference */
+ clocks =<&ref25>;
+
+ /* connect xtal input as source of pll0 and pll1 */
+ silabs,pll-source =<0 0>,<1 0>;
+
+ /*
+ * overwrite clkout0 configuration with:
+ * - 8mA output drive strength
+ * - pll0 as clock source of multisynth0
+ * - multisynth0 as clock source of output divider
+ * - multisynth0 can change pll0
+ * - set initial clock frequency of 74.25MHz
+ */
+ clkout0 {
+ reg =<0>;
+ silabs,drive-strength =<8>;
+ silabs,multisynth-source =<0>;
+ silabs,clock-source =<0>;
+ silabs,pll-master;
+ clock-frequency =<74250000>;
+ };
+
+ /*
+ * overwrite clkout1 configuration with:
+ * - 4mA output drive strength
+ * - pll1 as clock source of multisynth1
+ * - multisynth1 as clock source of output divider
+ * - multisynth1 can change pll1
+ */
+ clkout1 {
+ reg =<1>;
+ silabs,drive-strength =<4>;
+ silabs,multisynth-source =<1>;
+ silabs,clock-source =<0>;
+ pll-master;
+ };
+
Is definition of pll-master in clkout1 correct? should not be silabs,pll-
master ?

Good catch.

Sebastian
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