From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [PATCH v5] clk: change clk_ops' ->determine_rate() prototype Date: Tue, 7 Jul 2015 17:57:48 -0700 Message-ID: <20150708005748.GG30412@codeaurora.org> References: <1436294888-25752-1-git-send-email-boris.brezillon@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1436294888-25752-1-git-send-email-boris.brezillon@free-electrons.com> Sender: linux-doc-owner@vger.kernel.org To: Boris Brezillon Cc: Mike Turquette , linux-clk@vger.kernel.org, Jonathan Corbet , Tony Lindgren , Ralf Baechle , Emilio =?iso-8859-1?Q?L=F3pez?= , Maxime Ripard , Tero Kristo , Peter De Schrijver , Prashant Gaikwad , Stephen Warren , Thierry Reding , Alexandre Courbot , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-mips@linux-mips.org, linux-tegra@vger.kernel.org List-Id: linux-tegra@vger.kernel.org On 07/07, Boris Brezillon wrote: > Clock rates are stored in an unsigned long field, but ->determine_rat= e() > (which returns a rounded rate from a requested one) returns a long > value (errors are reported using negative error codes), which can lea= d > to long overflow if the clock rate exceed 2Ghz. >=20 > Change ->determine_rate() prototype to return 0 or an error code, and= pass > a pointer to a clk_rate_request structure containing the expected tar= get > rate and the rate constraints imposed by clk users. >=20 > The clk_rate_request structure might be extended in the future to con= tain > other kind of constraints like the rounding policy, the maximum clock > inaccuracy or other things that are not yet supported by the CCF > (power consumption constraints ?). >=20 > Signed-off-by: Boris Brezillon >=20 > CC: Jonathan Corbet > CC: Tony Lindgren > CC: Ralf Baechle > CC: "Emilio L=F3pez" > CC: Maxime Ripard > CC: Tero Kristo > CC: Peter De Schrijver > CC: Prashant Gaikwad > CC: Stephen Warren > CC: Thierry Reding > CC: Alexandre Courbot > CC: linux-doc@vger.kernel.org > CC: linux-kernel@vger.kernel.org > CC: linux-arm-kernel@lists.infradead.org > CC: linux-omap@vger.kernel.org > CC: linux-mips@linux-mips.org > CC: linux-tegra@vger.kernel.org >=20 > --- I'll throw this patch into -next now to see if any other problems shake out. I'm hoping we get some more acks though, so it'll be on it's own branch and become immutable in a week or so. One question below. > diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.= c > index 616f5ae..9e69f34 100644 > --- a/drivers/clk/clk-composite.c > +++ b/drivers/clk/clk-composite.c > @@ -99,33 +99,33 @@ static long clk_composite_determine_rate(struct c= lk_hw *hw, unsigned long rate, > =20 > parent_rate =3D __clk_get_rate(parent); > =20 > - tmp_rate =3D rate_ops->round_rate(rate_hw, rate, > + tmp_rate =3D rate_ops->round_rate(rate_hw, req->rate, > &parent_rate); > if (tmp_rate < 0) > continue; > =20 > - rate_diff =3D abs(rate - tmp_rate); > + rate_diff =3D abs(req->rate - tmp_rate); > =20 > - if (!rate_diff || !*best_parent_p > + if (!rate_diff || !req->best_parent_hw > || best_rate_diff > rate_diff) { > - *best_parent_p =3D __clk_get_hw(parent); > - *best_parent_rate =3D parent_rate; > + req->best_parent_hw =3D __clk_get_hw(parent); > + req->best_parent_rate =3D parent_rate; > best_rate_diff =3D rate_diff; > best_rate =3D tmp_rate; > } > =20 > if (!rate_diff) > - return rate; > + return 0; > } > =20 > - return best_rate; > + req->rate =3D best_rate; > + return 0; > } else if (mux_hw && mux_ops && mux_ops->determine_rate) { > __clk_hw_set_clk(mux_hw, hw); > - return mux_ops->determine_rate(mux_hw, rate, min_rate, > - max_rate, best_parent_rate, > - best_parent_p); > + return mux_ops->determine_rate(mux_hw, req); > } else { > pr_err("clk: clk_composite_determine_rate function called, but no = mux or rate callback set!\n"); > + req->rate =3D 0; > return 0; Shouldn't this return an error now? And then assigning req->rate wouldn't be necessary. Sorry I must have missed this last round. --=20 Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project