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Message-Id: <1423059614-10450-1-git-send-email-boris.brezillon@free-electrons.com>
Date: Wed, 4 Feb 2015 15:20:14 +0100
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: Mike Turquette <mturquette@...aro.org>
Cc: Nicolas Ferre <nicolas.ferre@...el.com>,
Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Bo Shen <voice.shen@...el.com>,
Boris Brezillon <boris.brezillon@...e-electrons.com>,
<stable@...r.kernel.org>
Subject: [PATCH] clk: at91: usb: propagate rate modification to the parent clk
The at91sam9n12 and at91sam9x5 usb clocks do not propagate rate
modification requests to their parents.
This causes a bug when the PLLB is left uninitialized by the bootloader
(PLL multiplier set to 0, or in other words, PLL rate = 0 Hz).
Implement the determinate_rate method and propagate the change rate
request to the parent clk.
Cc: <stable@...r.kernel.org> # v3.14+
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Reported-by: Bo Shen <voice.shen@...el.com>
Tested-by: Bo Shen <voice.shen@...el.com>
---
Hi Mike,
I haven't taken Tomeu's rework of the determine_rate prototype [1] into
account in this patch, but will do once his patch series is accepted.
Best Regards,
Boris
[1] https://lkml.org/lkml/2015/1/23/222
drivers/clk/at91/clk-usb.c | 62 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 47 insertions(+), 15 deletions(-)
diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c
index a23ac0c..0283a57 100644
--- a/drivers/clk/at91/clk-usb.c
+++ b/drivers/clk/at91/clk-usb.c
@@ -56,22 +56,53 @@ static unsigned long at91sam9x5_clk_usb_recalc_rate(struct clk_hw *hw,
return DIV_ROUND_CLOSEST(parent_rate, (usbdiv + 1));
}
-static long at91sam9x5_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate,
- unsigned long *parent_rate)
+static long at91sam9x5_clk_usb_determine_rate(struct clk_hw *hw,
+ unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk_hw **best_parent_hw)
{
- unsigned long div;
+ struct clk *parent = NULL;
+ long best_rate = -EINVAL;
+ unsigned long tmp_rate;
+ int best_diff = -1;
+ int tmp_diff;
+ int i;
- if (!rate)
- return -EINVAL;
+ for (i = 0; i < __clk_get_num_parents(hw->clk); i++) {
+ int div;
- if (rate >= *parent_rate)
- return *parent_rate;
+ parent = clk_get_parent_by_index(hw->clk, i);
+ if (!parent)
+ continue;
+
+ for (div = 1; div < SAM9X5_USB_MAX_DIV + 2; div++) {
+ unsigned long tmp_parent_rate;
+
+ tmp_parent_rate = rate * div;
+ tmp_parent_rate = __clk_round_rate(parent,
+ tmp_parent_rate);
+ tmp_rate = DIV_ROUND_CLOSEST(tmp_parent_rate, div);
+ if (tmp_rate < rate)
+ tmp_diff = rate - tmp_rate;
+ else
+ tmp_diff = tmp_rate - rate;
+
+ if (best_diff < 0 || best_diff > tmp_diff) {
+ best_rate = tmp_rate;
+ best_diff = tmp_diff;
+ *best_parent_rate = tmp_parent_rate;
+ *best_parent_hw = __clk_get_hw(parent);
+ }
+
+ if (!best_diff || tmp_rate < rate)
+ break;
+ }
- div = DIV_ROUND_CLOSEST(*parent_rate, rate);
- if (div > SAM9X5_USB_MAX_DIV + 1)
- div = SAM9X5_USB_MAX_DIV + 1;
+ if (!best_diff)
+ break;
+ }
- return DIV_ROUND_CLOSEST(*parent_rate, div);
+ return best_rate;
}
static int at91sam9x5_clk_usb_set_parent(struct clk_hw *hw, u8 index)
@@ -121,7 +152,7 @@ static int at91sam9x5_clk_usb_set_rate(struct clk_hw *hw, unsigned long rate,
static const struct clk_ops at91sam9x5_usb_ops = {
.recalc_rate = at91sam9x5_clk_usb_recalc_rate,
- .round_rate = at91sam9x5_clk_usb_round_rate,
+ .determine_rate = at91sam9x5_clk_usb_determine_rate,
.get_parent = at91sam9x5_clk_usb_get_parent,
.set_parent = at91sam9x5_clk_usb_set_parent,
.set_rate = at91sam9x5_clk_usb_set_rate,
@@ -159,7 +190,7 @@ static const struct clk_ops at91sam9n12_usb_ops = {
.disable = at91sam9n12_clk_usb_disable,
.is_enabled = at91sam9n12_clk_usb_is_enabled,
.recalc_rate = at91sam9x5_clk_usb_recalc_rate,
- .round_rate = at91sam9x5_clk_usb_round_rate,
+ .determine_rate = at91sam9x5_clk_usb_determine_rate,
.set_rate = at91sam9x5_clk_usb_set_rate,
};
@@ -179,7 +210,8 @@ at91sam9x5_clk_register_usb(struct at91_pmc *pmc, const char *name,
init.ops = &at91sam9x5_usb_ops;
init.parent_names = parent_names;
init.num_parents = num_parents;
- init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+ init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
+ CLK_SET_RATE_PARENT;
usb->hw.init = &init;
usb->pmc = pmc;
@@ -207,7 +239,7 @@ at91sam9n12_clk_register_usb(struct at91_pmc *pmc, const char *name,
init.ops = &at91sam9n12_usb_ops;
init.parent_names = &parent_name;
init.num_parents = 1;
- init.flags = CLK_SET_RATE_GATE;
+ init.flags = CLK_SET_RATE_GATE | CLK_SET_RATE_PARENT;
usb->hw.init = &init;
usb->pmc = pmc;
--
1.9.1
--
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