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From: kernel@martin.sperl.org
To: Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Lee Jones <lee@kernel.org>, Eric Anholt <eric@anholt.net>,
	Remi Pommarel <repk@triplefau.lt>,
	linux-clk@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org
Cc: Martin Sperl <kernel@martin.sperl.org>
Subject: [PATCH V4 1/7] clk: bcm2835: the minimum clock divider is 2
Date: Fri, 15 Jan 2016 14:21:00 +0000	[thread overview]
Message-ID: <1452867667-2447-2-git-send-email-kernel@martin.sperl.org> (raw)
In-Reply-To: <1452867667-2447-1-git-send-email-kernel@martin.sperl.org>

From: Martin Sperl <kernel@martin.sperl.org>

Testing with different clock divider values has shown
that (at least for the PCM clock) the clock divider
has to be at least 2, otherwise the clock will not
output a signal.

So the clamping has changed from 1 to 2 and comments
about the kind of clamping applied have been added.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
---
 drivers/clk/bcm/clk-bcm2835.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 015e687..10e97b7 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1178,7 +1178,11 @@ static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
 	div &= ~unused_frac_mask;
 
 	/* Clamp to the limits. */
-	div = max(div, unused_frac_mask + 1);
+
+	/* divider must be >= 2 */
+	div = max_t(u32, div, (2 << CM_DIV_FRAC_BITS));
+
+	/* clamp to max divider allowed */
 	div = min_t(u32, div, GENMASK(data->int_bits + CM_DIV_FRAC_BITS - 1,
 				      CM_DIV_FRAC_BITS - data->frac_bits));
 
-- 
1.7.10.4


  reply	other threads:[~2016-01-15 14:21 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-15 14:20 [PATCH V4 0/7] clk: bcm2835: add clocks and add MASH support kernel
2016-01-15 14:21 ` kernel [this message]
2016-02-01 23:15   ` [PATCH V4 1/7] clk: bcm2835: the minimum clock divider is 2 Eric Anholt
2016-02-02  1:52     ` Eric Anholt
2016-02-08 10:39       ` Martin Sperl
2016-02-08 10:28     ` Martin Sperl
2016-02-13  0:28       ` Eric Anholt
2016-01-15 14:21 ` [PATCH V4 2/7] clk: bcm2835: clamp clock divider to highest integer only kernel
2016-02-01 23:19   ` Eric Anholt
2016-02-08 12:20     ` Martin Sperl
2016-01-15 14:21 ` [PATCH V4 3/7] clk: bcm2835: remove use of BCM2835_CLOCK_COUNT in driver kernel
     [not found] ` <1452867667-2447-1-git-send-email-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2016-01-15 14:21   ` [PATCH V4 4/7] clk: bcm2835: enable management of PCM clock kernel-TqfNSX0MhmxHKSADF0wUEw
2016-01-15 14:21 ` [PATCH V4 5/7] clk: bcm2835: add missing 22 HW-clocks kernel
2016-02-02  1:51   ` Eric Anholt
2016-02-08 11:12     ` Martin Sperl
2016-02-17 18:25       ` Martin Sperl
2016-02-17 20:01         ` Stefan Wahren
2016-01-15 14:21 ` [PATCH V4 6/7] clk: bcm2835: enable fractional and mash support kernel
2016-01-15 14:21 ` [PATCH V4 7/7] clk: bcm2835: apply limits on dividers to MASH mode kernel
2016-01-16  9:40 ` [PATCH V4 0/7] clk: bcm2835: add clocks and add MASH support Martin Sperl

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