56 lines
2.2 KiB
Diff
56 lines
2.2 KiB
Diff
From 1b6867ee05d84cc6ec23b5ec0b78684187d3190a Mon Sep 17 00:00:00 2001
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From: Boris Brezillon <boris.brezillon@bootlin.com>
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Date: Wed, 7 Mar 2018 15:41:14 +0100
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Subject: [PATCH] clk: bcm2835: Make sure the PLL is gated before changing its
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rate
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All bcm2835 PLLs should be gated before their rate can be changed.
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Setting CLK_SET_RATE_GATE will let the core enforce that, but this is
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not enough to make the code work in all situations. Indeed, the
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CLK_SET_RATE_GATE flag prevents a user from changing the rate while
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the clock is enabled, but this check only guarantees there's no Linux
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users. In our case, the clock might have been enabled by the
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bootloader/FW, and, because we have CLK_IGNORE_UNUSED set, Linux never
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disables the PLL. So we have to make sure the PLL is actually disabled
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before changing the rate.
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Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the audio domain clocks")
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Cc: <stable@vger.kernel.org>
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Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
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---
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drivers/clk/bcm/clk-bcm2835.c | 14 +++++++++++++-
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1 file changed, 13 insertions(+), 1 deletion(-)
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diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
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index 6c5d4a8e426c..051ce769c109 100644
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--- a/drivers/clk/bcm/clk-bcm2835.c
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+++ b/drivers/clk/bcm/clk-bcm2835.c
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@@ -678,6 +678,18 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
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u32 ana[4];
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int i;
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+ /*
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+ * Normally, the CLK_SET_RATE_GATE flag prevents a user from changing
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+ * the rate while the clock is enabled, but this check only makes sure
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+ * there's no Linux users.
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+ * In our case, the clock might have been enabled by the bootloader/FW,
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+ * and, since CLK_IGNORE_UNUSED flag is set, Linux never disables it.
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+ * So we have to make sure the clk is actually disabled before changing
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+ * the rate.
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+ */
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+ if (bcm2835_pll_is_on(hw))
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+ bcm2835_pll_off(hw);
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+
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if (rate > data->max_fb_rate) {
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use_fb_prediv = true;
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rate /= 2;
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@@ -1318,7 +1330,7 @@ static struct clk_hw *bcm2835_register_pll(struct bcm2835_cprman *cprman,
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init.num_parents = 1;
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init.name = data->name;
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init.ops = &bcm2835_pll_clk_ops;
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- init.flags = CLK_IGNORE_UNUSED;
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+ init.flags = CLK_IGNORE_UNUSED | CLK_SET_RATE_GATE;
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pll = kzalloc(sizeof(*pll), GFP_KERNEL);
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if (!pll)
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