From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@free-electrons.com (Boris Brezillon) Date: Fri, 7 Nov 2014 18:58:35 +0100 Subject: [PATCH 2/2] clk: at91: usb: fix at91sam9x5 recalc, round and set rate In-Reply-To: <20141107175139.GF4068@piout.net> References: <1415179995-25062-1-git-send-email-boris.brezillon@free-electrons.com> <1415179995-25062-3-git-send-email-boris.brezillon@free-electrons.com> <20141107175139.GF4068@piout.net> Message-ID: <20141107185835.1fd3871a@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 7 Nov 2014 18:51:39 +0100 Alexandre Belloni wrote: > On 05/11/2014 at 10:33:15 +0100, Boris Brezillon wrote : > > First check for rate == 0 in set_rate and round_rate to avoid div by zero. > > Then, in order to get the closest rate, round all divisions to the closest > > result instead of rounding them down. > > > > Signed-off-by: Boris Brezillon > > --- > > drivers/clk/at91/clk-usb.c | 29 +++++++++++++++++------------ > > 1 file changed, 17 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c > > index 5b3b63c..7980e8c 100644 > > --- a/drivers/clk/at91/clk-usb.c > > +++ b/drivers/clk/at91/clk-usb.c > > @@ -52,7 +52,8 @@ static unsigned long at91sam9x5_clk_usb_recalc_rate(struct clk_hw *hw, > > > > tmp = pmc_read(pmc, AT91_PMC_USB); > > usbdiv = (tmp & AT91_PMC_OHCIUSBDIV) >> SAM9X5_USB_DIV_SHIFT; > > - return parent_rate / (usbdiv + 1); > > + > > + return DIV_ROUND_CLOSEST(parent_rate, (usbdiv + 1)); > > } > > > > static long at91sam9x5_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate, > > @@ -62,19 +63,19 @@ static long at91sam9x5_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate, > > unsigned long bestrate; > > unsigned long tmp; > > > > + if (!rate) > > + return DIV_ROUND_CLOSEST(*parent_rate, SAM9X5_USB_MAX_DIV + 1); > > + > > Maybe I'm missing something but I would return -EINVAL here. That's what I did at first, but just realized maybe 0 is a valid request and we should try to be as close as possible to 0. Anyway, I'm not really convinced we need that, so I can drop it. > > > if (rate >= *parent_rate) > > return *parent_rate; > > > > - div = *parent_rate / rate; > > - if (div >= SAM9X5_USB_MAX_DIV) > > - return *parent_rate / (SAM9X5_USB_MAX_DIV + 1); > > + div = DIV_ROUND_CLOSEST(*parent_rate, rate); > > + if (div > SAM9X5_USB_MAX_DIV + 1) > > + div = SAM9X5_USB_MAX_DIV + 1; > > + else if (!div) > > + div = 1; > > In that case, you are also screwed, I would return -EINVAL. Well, actually that cannot happen, because I already tested rate >= *parent_rate. I'll remove that line. -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com