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Commit 13a6073d authored by Boris Brezillon's avatar Boris Brezillon Committed by Mike Turquette
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clk: at91: rework rm9200 USB clock to propagate set_rate to the parent clk 



The RM9200 USB clock is actually connected to a single parent (the PLLB)
on which we can apply a specific divider.
The USB clock divider does not allow for fine grained control on the USB
clock frequency, hence propagating the set_rate request to the parent is
the only choice we have to properly configure the USB clock rate.

Signed-off-by: default avatarBoris BREZILLON <boris.brezillon@free-electrons.com>
Reported-by: default avatarGaël PORTAY <gael.portay@gmail.com>
Tested-by: default avatarGaël PORTAY <gael.portay@gmail.com>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent 87e2ed33

drivers/clk/at91/clk-usb.c

+10 −3
Original line number Diff line number Diff line
@@ -238,16 +238,22 @@ static long at91rm9200_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate, 
					  unsigned long *parent_rate)

{

	struct at91rm9200_clk_usb *usb = to_at91rm9200_clk_usb(hw);

	struct clk *parent = __clk_get_parent(hw->clk);

	unsigned long bestrate = 0;

	int bestdiff = -1;

	unsigned long tmprate;

	int tmpdiff;

	int i = 0;



	for (i = 0; i < 4; i++) {

	for (i = 0; i < RM9200_USB_DIV_TAB_SIZE; i++) {

		unsigned long tmp_parent_rate;



		if (!usb->divisors[i])

			continue;

		tmprate = *parent_rate / usb->divisors[i];



		tmp_parent_rate = rate * usb->divisors[i];

		tmp_parent_rate = __clk_round_rate(parent, tmp_parent_rate);

		tmprate = tmp_parent_rate / usb->divisors[i];

		if (tmprate < rate)

			tmpdiff = rate - tmprate;

		else
@@ -256,6 +262,7 @@ static long at91rm9200_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate, 
		if (bestdiff < 0 || bestdiff > tmpdiff) {

			bestrate = tmprate;

			bestdiff = tmpdiff;

			*parent_rate = tmp_parent_rate;

		}



		if (!bestdiff)
@@ -311,7 +318,7 @@ at91rm9200_clk_register_usb(struct at91_pmc *pmc, const char *name, 
	init.ops = &at91rm9200_usb_ops;

	init.parent_names = &parent_name;

	init.num_parents = 1;

	init.flags = 0;

	init.flags = CLK_SET_RATE_PARENT;



	usb->hw.init = &init;

	usb->pmc = pmc;