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    Subject[PATCH 4.0 088/220] clk: at91: usb: propagate rate modification to the parent clk
    Date
    4.0-stable review patch.  If anyone has any objections, please let me know.

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

    From: Boris Brezillon <boris.brezillon@free-electrons.com>

    commit 4591243102faa8de92da320edea47219901461e9 upstream.

    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.

    Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
    Reported-by: Bo Shen <voice.shen@atmel.com>
    Tested-by: Bo Shen <voice.shen@atmel.com>
    Signed-off-by: Michael Turquette <mturquette@linaro.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/clk/at91/clk-usb.c | 72 +++++++++++++++++++++++++++++++++------------
    1 file changed, 53 insertions(+), 19 deletions(-)

    --- a/drivers/clk/at91/clk-usb.c
    +++ b/drivers/clk/at91/clk-usb.c
    @@ -56,22 +56,55 @@ static unsigned long at91sam9x5_clk_usb_
    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)
    -{
    - unsigned long div;
    -
    - if (!rate)
    - return -EINVAL;
    -
    - if (rate >= *parent_rate)
    - return *parent_rate;
    -
    - div = DIV_ROUND_CLOSEST(*parent_rate, rate);
    - if (div > SAM9X5_USB_MAX_DIV + 1)
    - div = SAM9X5_USB_MAX_DIV + 1;
    +static long at91sam9x5_clk_usb_determine_rate(struct clk_hw *hw,
    + unsigned long rate,
    + unsigned long min_rate,
    + unsigned long max_rate,
    + unsigned long *best_parent_rate,
    + struct clk_hw **best_parent_hw)
    +{
    + struct clk *parent = NULL;
    + long best_rate = -EINVAL;
    + unsigned long tmp_rate;
    + int best_diff = -1;
    + int tmp_diff;
    + int i;
    +
    + for (i = 0; i < __clk_get_num_parents(hw->clk); i++) {
    + int div;
    +
    + 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;
    + }
    +
    + 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 +154,7 @@ static int at91sam9x5_clk_usb_set_rate(s

    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 +192,7 @@ static const struct clk_ops at91sam9n12_
    .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 +212,8 @@ at91sam9x5_clk_register_usb(struct at91_
    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 +241,7 @@ at91sam9n12_clk_register_usb(struct at91
    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;



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