From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH v2 06/14] ARM: sun8i: clk: Add clk-factor rate application method Date: Thu, 30 Jun 2016 22:40:01 +0200 Message-ID: <20160630204001.GC5485@lukather> References: <20160625034511.7966-1-megous@megous.com> <20160625034511.7966-7-megous@megous.com> Reply-To: maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="2JFBq9zoW8cOFH7v" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: <20160625034511.7966-7-megous-5qf/QAjKc83QT0dZR+AlfA@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: megous-5qf/QAjKc83QT0dZR+AlfA@public.gmane.org Cc: dev-3kdeTeqwOZ9EV1b7eY7vFQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Michael Turquette , Stephen Boyd , Rob Herring , Mark Rutland , Chen-Yu Tsai , Emilio =?iso-8859-1?Q?L=F3pez?= , "open list:COMMON CLK FRAMEWORK" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list List-Id: devicetree@vger.kernel.org --2JFBq9zoW8cOFH7v Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Hi, On Sat, Jun 25, 2016 at 05:45:03AM +0200, megous-5qf/QAjKc83QT0dZR+AlfA@public.gmane.org wrote: > From: Ondrej Jirman > > PLL1 on H3 requires special factors application algorithm, > when the rate is changed. This algorithm was extracted > from the arisc code that handles frequency scaling > in the BSP kernel. > > This commit adds optional apply function to > struct factors_data, that can implement non-trivial > factors application method, when necessary. > > Also struct clk_factors_config is extended with position > of the PLL lock flag. Have you tested the current implementation, and found that it was not working, or did you duplicate the arisc code directly? > /** > + * sun8i_h3_apply_pll1_factors() - applies n, k, m, p factors to the > + * register using an algorithm that tries to reserve the PLL lock > + */ > + > +static void sun8i_h3_apply_pll1_factors(struct clk_factors *factors, struct factors_request *req) > +{ > + const struct clk_factors_config *config = factors->config; > + u32 reg; > + > + /* Fetch the register value */ > + reg = readl(factors->reg); > + > + if (FACTOR_GET(config->pshift, config->pwidth, reg) < req->p) { > + reg = FACTOR_SET(config->pshift, config->pwidth, reg, req->p); > + > + writel(reg, factors->reg); > + __delay(2000); > + } So there was some doubts about the fact that P was being used, or at least that it was useful. > + if (FACTOR_GET(config->mshift, config->mwidth, reg) < req->m) { > + reg = FACTOR_SET(config->mshift, config->mwidth, reg, req->m); > + > + writel(reg, factors->reg); > + __delay(2000); > + } > + > + reg = FACTOR_SET(config->nshift, config->nwidth, reg, req->n); > + reg = FACTOR_SET(config->kshift, config->kwidth, reg, req->k); > + > + writel(reg, factors->reg); > + __delay(20); > + > + while (!(readl(factors->reg) & (1 << config->lock))); So, they are applying the dividers first, and then applying the multipliers, and then wait for the PLL to stabilize. > + > + if (FACTOR_GET(config->mshift, config->mwidth, reg) > req->m) { > + reg = FACTOR_SET(config->mshift, config->mwidth, reg, req->m); > + > + writel(reg, factors->reg); > + __delay(2000); > + } > + > + if (FACTOR_GET(config->pshift, config->pwidth, reg) > req->p) { > + reg = FACTOR_SET(config->pshift, config->pwidth, reg, req->p); > + > + writel(reg, factors->reg); > + __delay(2000); > + } However, this is kind of weird, why would you need to re-apply the dividers? Nothing really changes. Have you tried without that part? Since this is really specific, I guess you could simply make the clk_ops for the nkmp clocks public, and just re-implement set_rate using that logic. You might also need to set an upper limit on P, since the last value (4) is not a valid one. I guess you could do that by adding a max field in the __ccu_div structure. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --2JFBq9zoW8cOFH7v--