From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sun, 8 Apr 2018 05:44:23 -0400 From: Marcin To: Boris Brezillon , Nicolas Ferre , Alexandre Belloni Cc: Michael Turquette , Stephen Boyd , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] clk: at91: Fix for PLL set_rate changes not being actually written to PLL peripheral bits Message-ID: <20180408094423.GA51702@hak8or> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii List-ID: 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. Looking around, I saw the USB bus was running at half speed. Going further, it seems that in ..._set_rate() the PLL wasn't actually being adjusted. Writing the multiplier and divider values to the peripheral fixes the bus running at half speed. Signed-off-by: Marcin Ziemianowicz --- drivers/clk/at91/clk-pll.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/clk/at91/clk-pll.c b/drivers/clk/at91/clk-pll.c index 534961766ae5..db7155fe9346 100644 --- a/drivers/clk/at91/clk-pll.c +++ b/drivers/clk/at91/clk-pll.c @@ -288,6 +288,14 @@ static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate, pll->div = div; pll->mul = mul; + // Set the PLL as per above div and mil values. + regmap_update_bits(pll->regmap, AT91_CKGR_PLLBR, + AT91_PMC_DIV | AT91_PMC_MUL, + (div << 0) | (mul << 16)); + + pr_debug("clk-pll: setting new rate, (%lu hz / %u) * %u = %lu hz\n", + parent_rate, div, mul, rate); + return 0; } -- 2.16.3