[PATCH v2] clk: si5351: Add PLL soft reset

From	Jacob Siverskog <jacob@teenage.engineering>
Newsgroups	linux.kernel
Subject	[PATCH v2] clk: si5351: Add PLL soft reset
Date	2015-11-20 18:30 +0100
Message-ID	<qwXFw-1Np-3@gated-at.bofh.it> (permalink)
References	<qwXFw-1Np-5@gated-at.bofh.it> <qwXFw-1Np-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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This is according to figure 12 ("I2C Programming Procedure") in
"Si5351A/B/C Data Sheet"
(https://www.silabs.com/Support%20Documents/TechnicalDocs/Si5351-B.pdf).

Without the PLL soft reset, we were unable to get three outputs
working at the same time.

According to Silicon Labs support, performing PLL soft reset will only
be noticeable if the PLL parameters have been changed.

Signed-off-by: Jacob Siverskog <jacob@teenage.engineering>
Signed-off-by: Jens Rudberg <jens@teenage.engineering>
---
 drivers/clk/clk-si5351.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
index e346b22..984c058 100644
--- a/drivers/clk/clk-si5351.c
+++ b/drivers/clk/clk-si5351.c
@@ -1091,6 +1091,12 @@ static int si5351_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
 	si5351_set_bits(hwdata->drvdata, SI5351_CLK0_CTRL + hwdata->num,
 			SI5351_CLK_POWERDOWN, 0);
 
+	/* do a pll soft reset on both plls, needed in some cases to get all
+	 * outputs running
+	 */
+	si5351_reg_write(hwdata->drvdata, SI5351_PLL_RESET,
+			 SI5351_PLL_RESET_A | SI5351_PLL_RESET_B);
+
 	dev_dbg(&hwdata->drvdata->client->dev,
 		"%s - %s: rdiv = %u, parent_rate = %lu, rate = %lu\n",
 		__func__, clk_hw_get_name(hw), (1 << rdiv),
-- 
2.6.3

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[PATCH v2] clk: si5351: Add PLL soft reset Jacob Siverskog <jacob@teenage.engineering> - 2015-11-20 18:30 +0100
  Re: [PATCH v2] clk: si5351: Add PLL soft reset Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-20 19:00 +0100
    [PATCH v3 0/1] clk: si5351: Add PLL soft reset Jacob Siverskog <jacob@teenage.engineering> - 2015-11-20 19:10 +0100
      [PATCH v3 1/1] clk: si5351: Add PLL soft reset Jacob Siverskog <jacob@teenage.engineering> - 2015-11-20 19:10 +0100
        Re: [PATCH v3 1/1] clk: si5351: Add PLL soft reset Stephen Boyd <sboyd@codeaurora.org> - 2015-11-20 19:50 +0100

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