linux-kernel - [PATCH 4.5 209/238] clk: bcm2835: Fix setting of PLL divider clock rates

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Date:	Sun, 10 Apr 2016 11:36:26 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Eric Anholt <eric@...olt.net>,
	Michael Turquette <mturquette@...libre.com>
Subject: [PATCH 4.5 209/238] clk: bcm2835: Fix setting of PLL divider clock rates

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Anholt <eric@...olt.net>

commit 773b3966dd3cdaeb68e7f2edfe5656abac1dc411 upstream.

Our dividers weren't being set successfully because CM_PASSWORD wasn't
included in the register write.  It looks easier to just compute the
divider to write ourselves than to update clk-divider for the ability
to OR in some arbitrary bits on write.

Fixes about half of the video modes on my HDMI monitor (everything
except 720x400).

Signed-off-by: Eric Anholt <eric@...olt.net>
Signed-off-by: Michael Turquette <mturquette@...libre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/clk/bcm/clk-bcm2835.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1107,13 +1107,15 @@ static int bcm2835_pll_divider_set_rate(
 	struct bcm2835_pll_divider *divider = bcm2835_pll_divider_from_hw(hw);
 	struct bcm2835_cprman *cprman = divider->cprman;
 	const struct bcm2835_pll_divider_data *data = divider->data;
-	u32 cm;
-	int ret;
+	u32 cm, div, max_div = 1 << A2W_PLL_DIV_BITS;
 
-	ret = clk_divider_ops.set_rate(hw, rate, parent_rate);
-	if (ret)
-		return ret;
+	div = DIV_ROUND_UP_ULL(parent_rate, rate);
 
+	div = min(div, max_div);
+	if (div == max_div)
+		div = 0;
+
+	cprman_write(cprman, data->a2w_reg, div);
 	cm = cprman_read(cprman, data->cm_reg);
 	cprman_write(cprman, data->cm_reg, cm | data->load_mask);
 	cprman_write(cprman, data->cm_reg, cm & ~data->load_mask);