From: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> [ Upstream commit b0ecf1c6c6e82da4847900fad0272abfd014666d ] clk_hw_round_rate() may call round rate function of its parents. In case of SAM9X60 two of USB parrents are PLLA and UPLL. These clocks are controlled by clk-sam9x60-pll.c driver. The round rate function for this driver is sam9x60_pll_round_rate() which call in turn sam9x60_pll_get_best_div_mul(). In case the requested rate is not in the proper range (rate < characteristics->output[0].min && rate > characteristics->output[0].max) the sam9x60_pll_round_rate() will return a negative number to its caller (called by clk_core_round_rate_nolock()). clk_hw_round_rate() will return zero in case a negative number is returned by clk_core_round_rate_nolock(). With this, the USB clock will continue its rate computation even caller of clk_hw_round_rate() returned an error. With this, the USB clock on SAM9X60 may not chose the best parent. I detected this after a suspend/resume cycle on SAM9X60. Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/1579261009-4573-2-git-send-email-claudiu.beznea@xxxxxxxxxxxxx Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/clk/at91/clk-usb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c index 8ab8502778a28..55e09641b491b 100644 --- a/drivers/clk/at91/clk-usb.c +++ b/drivers/clk/at91/clk-usb.c @@ -79,6 +79,9 @@ static int at91sam9x5_clk_usb_determine_rate(struct clk_hw *hw, tmp_parent_rate = req->rate * div; tmp_parent_rate = clk_hw_round_rate(parent, tmp_parent_rate); + if (!tmp_parent_rate) + continue; + tmp_rate = DIV_ROUND_CLOSEST(tmp_parent_rate, div); if (tmp_rate < req->rate) tmp_diff = req->rate - tmp_rate; -- 2.20.1
