4.17-stable review patch. If anyone has any objections, please let me know.
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From: Marcin Ziemianowicz marcin@ziemianowicz.com
commit a982e45dc150da3a08907b6dd676b735391704b4 upstream.
When a USB device is connected to the USB host port on the SAM9N12 then you get "-62" error which seems to indicate USB replies from the device are timing out. Based on a logic sniffer, I saw the USB bus was running at half speed.
The PLL code uses cached MUL and DIV values which get set in set_rate() and applied in prepare(), but the recalc_rate() function instead queries the hardware instead of using these cached values. Therefore, if recalc_rate() is called between a set_rate() and prepare(), the wrong frequency is calculated and later the USB clock divider for the SAM9N12 SOC will be configured for an incorrect clock.
In my case, the PLL hardware was set to 96 Mhz before the OHCI driver loads, and therefore the usb clock divider was being set to /2 even though the OHCI driver set the PLL to 48 Mhz.
As an alternative explanation, I noticed this was fixed in the past by 87e2ed338f1b ("clk: at91: fix recalc_rate implementation of PLL driver") but the bug was later re-introduced by 1bdf02326b71 ("clk: at91: make use of syscon/regmap internally").
Fixes: 1bdf02326b71 ("clk: at91: make use of syscon/regmap internally) Cc: stable@vger.kernel.org Signed-off-by: Marcin Ziemianowicz marcin@ziemianowicz.com Acked-by: Boris Brezillon boris.brezillon@bootlin.com Signed-off-by: Stephen Boyd sboyd@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/clk/at91/clk-pll.c | 13 +------------ 1 file changed, 1 insertion(+), 12 deletions(-)
--- a/drivers/clk/at91/clk-pll.c +++ b/drivers/clk/at91/clk-pll.c @@ -132,19 +132,8 @@ static unsigned long clk_pll_recalc_rate unsigned long parent_rate) { struct clk_pll *pll = to_clk_pll(hw); - unsigned int pllr; - u16 mul; - u8 div;
- regmap_read(pll->regmap, PLL_REG(pll->id), &pllr); - - div = PLL_DIV(pllr); - mul = PLL_MUL(pllr, pll->layout); - - if (!div || !mul) - return 0; - - return (parent_rate / div) * (mul + 1); + return (parent_rate / pll->div) * (pll->mul + 1); }
static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate,