kernel/bcm283x-clk-audio-fixes.patch

From aa964d59aab2cb04bc011ffd370822ac79f82a0b Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@bootlin.com>
Date: Wed, 7 Mar 2018 15:39:17 +0100
Subject: [PATCH] clk: bcm2835: De-assert/assert PLL reset signal when
 appropriate

In order to enable a PLL, not only the PLL has to be powered up and
locked, but you also have to de-assert the reset signal. The last part
was missing. Add it so PLLs that were not enabled by the FW/bootloader
can be enabled from Linux.

Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the audio domain clocks")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
 drivers/clk/bcm/clk-bcm2835.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index a07f6451694a..6c5d4a8e426c 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -602,6 +602,9 @@ static void bcm2835_pll_off(struct clk_hw *hw)
 	const struct bcm2835_pll_data *data = pll->data;
 
 	spin_lock(&cprman->regs_lock);
+	cprman_write(cprman, data->a2w_ctrl_reg,
+		     cprman_read(cprman, data->a2w_ctrl_reg) &
+		     ~A2W_PLL_CTRL_PRST_DISABLE);
 	cprman_write(cprman, data->cm_ctrl_reg,
 		     cprman_read(cprman, data->cm_ctrl_reg) |
 		     CM_PLL_ANARST);
@@ -640,6 +643,10 @@ static int bcm2835_pll_on(struct clk_hw *hw)
 		cpu_relax();
 	}
 
+	cprman_write(cprman, data->a2w_ctrl_reg,
+		     cprman_read(cprman, data->a2w_ctrl_reg) |
+		     A2W_PLL_CTRL_PRST_DISABLE);
+
 	return 0;
 }
 
From 1b6867ee05d84cc6ec23b5ec0b78684187d3190a Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@bootlin.com>
Date: Wed, 7 Mar 2018 15:41:14 +0100
Subject: [PATCH] clk: bcm2835: Make sure the PLL is gated before changing its
 rate

All bcm2835 PLLs should be gated before their rate can be changed.
Setting CLK_SET_RATE_GATE will let the core enforce that, but this is
not enough to make the code work in all situations. Indeed, the
CLK_SET_RATE_GATE flag prevents a user from changing the rate while
the clock is enabled, but this check only guarantees there's no Linux
users. In our case, the clock might have been enabled by the
bootloader/FW, and, because we have CLK_IGNORE_UNUSED set, Linux never
disables the PLL. So we have to make sure the PLL is actually disabled
before changing the rate.

Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the audio domain clocks")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
 drivers/clk/bcm/clk-bcm2835.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 6c5d4a8e426c..051ce769c109 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -678,6 +678,18 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
 	u32 ana[4];
 	int i;
 
+	/*
+	 * Normally, the CLK_SET_RATE_GATE flag prevents a user from changing
+	 * the rate while the clock is enabled, but this check only makes sure
+	 * there's no Linux users.
+	 * In our case, the clock might have been enabled by the bootloader/FW,
+	 * and, since CLK_IGNORE_UNUSED flag is set, Linux never disables it.
+	 * So we have to make sure the clk is actually disabled before changing
+	 * the rate.
+	 */
+	if (bcm2835_pll_is_on(hw))
+		bcm2835_pll_off(hw);
+
 	if (rate > data->max_fb_rate) {
 		use_fb_prediv = true;
 		rate /= 2;
@@ -1318,7 +1330,7 @@ static struct clk_hw *bcm2835_register_pll(struct bcm2835_cprman *cprman,
 	init.num_parents = 1;
 	init.name = data->name;
 	init.ops = &bcm2835_pll_clk_ops;
-	init.flags = CLK_IGNORE_UNUSED;
+	init.flags = CLK_IGNORE_UNUSED | CLK_SET_RATE_GATE;
 
 	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
 	if (!pll)