From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 30 Jun 2016 22:40:01 +0200 From: Maxime Ripard To: megous@megous.com Cc: dev@linux-sunxi.org, linux-arm-kernel@lists.infradead.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 Subject: Re: [PATCH v2 06/14] ARM: sun8i: clk: Add clk-factor rate application method Message-ID: <20160630204001.GC5485@lukather> References: <20160625034511.7966-1-megous@megous.com> <20160625034511.7966-7-megous@megous.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="2JFBq9zoW8cOFH7v" In-Reply-To: <20160625034511.7966-7-megous@megous.com> List-ID: --2JFBq9zoW8cOFH7v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Sat, Jun 25, 2016 at 05:45:03AM +0200, megous@megous.com wrote: > From: Ondrej Jirman >=20 > 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. >=20 > This commit adds optional apply function to > struct factors_data, that can implement non-trivial > factors application method, when necessary. >=20 > 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, str= uct factors_request *req) > +{ > + const struct clk_factors_config *config =3D factors->config; > + u32 reg; > + > + /* Fetch the register value */ > + reg =3D readl(factors->reg); > + > + if (FACTOR_GET(config->pshift, config->pwidth, reg) < req->p) { > + reg =3D 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 =3D FACTOR_SET(config->mshift, config->mwidth, reg, req->m); > + > + writel(reg, factors->reg); > + __delay(2000); > + } > + > + reg =3D FACTOR_SET(config->nshift, config->nwidth, reg, req->n); > + reg =3D 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 =3D 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 =3D 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 --=20 Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --2JFBq9zoW8cOFH7v Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJXdYOhAAoJEBx+YmzsjxAgzR4QAL1Bbup57A7vQfC+ANzgg+rq e0jZNc/c3Z/yphg5ixmDQ2dDqrNjRKuehAcgejRaEKRVvSPhK2N+WK16n6fBXDdv Kzi0axLyq2Jq/Hptsa+AT3EDmG0DJ8rj/lp2lEc1C7dPfVukf5rh1fFe26jHIa2t CIHBWwBxzdytxiiY7n/MPhELRULyYe96UHjfnjCiBZG6XAB0DuBKw9+BaZvTk5rU jrmfePNx7nPG1yvCC+OS7/Gg+p4rnlPpeP4VrmrP0OZGqGJRsP8eGJszQT+hfOjJ oe1n2oi2I5gqc/VkZBosvRstILiFMldoMXO9dExSiqBiwDoSmcdZfbMDDC9A3d2g xmLL4tpM4iut0Qi18acVINZ7MFogrOnFTQMUN+JmhxTgiMbfh9QipyWV892TfTk4 vTEd1zIb+hdFnsNghlUh8zpYBC52crtadsIz3HUqZbyuh3MIQP3zRK0hI2QrKUz2 2+jFxfOn1OOMdyYVggAUyhn3iJ4I+ksPQprfUAFu47PxodXdeWw7Gt0N7fVw336p S6/w5l7kXrD+bwQFj16/bWanEwvHsIv42HhNgslQHbtPpJS0sQElxN6fs8qNLe/1 oCJJS/xk63Ku011jJYa9rvuhAT1BZlhi0hIsbnL5R6cbYm2MQqry6zVpKRFXZrNb 9B13S8poycqalBEUnxyF =YDC5 -----END PGP SIGNATURE----- --2JFBq9zoW8cOFH7v--