From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:39750 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752027Ab3HNJ5A (ORCPT ); Wed, 14 Aug 2013 05:57:00 -0400 Date: Wed, 14 Aug 2013 11:56:52 +0200 From: Sascha Hauer Subject: Re: [alsa-devel] [PATCH v4 resent 1/2] ASoC: fsl: Add S/PDIF CPU DAI driver Message-ID: <20130814095652.GX26614@pengutronix.de> References: <51808310dd97d2a35a28766ed7309f269521cafd.1376309076.git.b42378@freescale.com> <20130814075017.GE2324@pengutronix.de> <20130814084801.GH31651@MrMyself> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130814084801.GH31651@MrMyself> Sender: devicetree-owner@vger.kernel.org To: Nicolin Chen Cc: devicetree@vger.kernel.org, alsa-devel@alsa-project.org, lars@metafoo.de, timur@tabi.org, rob.herring@calxeda.com, broonie@kernel.org, p.zabel@pengutronix.de, linuxppc-dev@lists.ozlabs.org List-ID: On Wed, Aug 14, 2013 at 04:48:02PM +0800, Nicolin Chen wrote: > Hi Sascha, > > On Wed, Aug 14, 2013 at 09:50:17AM +0200, Sascha Hauer wrote: > > > + - tx-clksrc-names : The names for all available clock sources for tx, which > > > + is also being listed in SoC reference manual, ClkSrc_Sel bit of SPDIF_SRPC. > > > + And the name list would be different between different SoC. Use 'null' for > > > + those unlisted names, and the max number of tx-clksrc-names should be 8. > > > + > > > + - rx-clksrc-names : The names for all available clock sources for rx, which > > > + is also being listed in SoC reference manual, TxClk_Source bit of SPDIF_STC. > > > + And the name list would be different between different SoC. Use 'null' for > > > + those unlisted names, and the max number of rx-clksrc-names should be 16. > > > + > > > +Optional properties: > > > + > > > + - rx-clksrc-lock: This is a boolean property. If present, ClkSrc_Sel bit > > > + of SPDIF_SRPC would be set a clock source that cares DPLL locked condition. > > > + > > > +Example1: > > > + > > > +spdif: spdif@02004000 { > > > + clocks = <&clks 197>; > > > + clock-names = "core"; > > > + rx-clksrc-lock; > > > + rx-clksrc-names = > > > + "lock.ext", "lock.spdif", "lock.asrc", > > > + "lock.spdif_ext", "lock.esai", "ext", > > > + "spdif", "asrc", "spdif_ext", "esai", > > > + "lock.mlb", "lock.mlb_phy", "mlb", > > > + "mlb_phy"; > > > + tx-clksrc-names = > > > + "xtal", "spdif", "asrc", "spdif_ext", > > > + "esai", "ipg", "mlb", "mlb_phy"; > > > > I had a hard time understanding what you are doing here. > > > > With this the clk names in arch/arm/mach-imx/clk-imx6q.c become an API > > between the Kernel and the devicetree. Don't do that. > > > > There is a standardized devicetree binding for clocks. Use it. > > I think I should first explain to you what this part is doing: > The driver needs to set Clk_source bit for TX/RX to select the > clock from a clock mux. The names listed above are those of the > clocks connecting to the mux, while they are not only internal > clocks which're included in clk-imx6q.c but also external ones, > an on-board external osc for example. > > The driver does get the clock by using the standard DT binding, > see the 'clocks = <&clks 197>' above, and then compare this > obtained clock->name with the name list to decide which value > should be set to the Clk_source bit. > > ================================================================== > ClkSrc_Sel from i.MX6Q reference manual: > > Clock source selection, all other settings not shown are reserved: > 0000 if (DPLL Locked) SPDIF_RxClk else extal > 0001 if (DPLL Locked) SPDIF_RxClk else spdif_clk > 0010 if (DPLL Locked) SPDIF_RxClk else asrc_clk > 0011 if (DPLL Locked) SPDIF_RxClk else spdif_extclk > 0100 if (DPLL Locked) SPDIF_Rxclk else esai_hckt > 0101 extal_clk > 0110 spdif_clk > 0111 asrc_clk > 1000 spdif_extclk > 1001 esai_hckt > 1010 if (DPLL Locked) SPDIF_RxClk else mlb_clk > ================================================================== > > So the name list here basically is not being used to obtain a > clock like what standardized DT binding does but to provide the > driver a full list to look up which value should be exactly used > according to the obtained clock. > > I think I should revise the binding doc for these two lists. It > might be hard to explain within that kinda short paragraph. > > Surely, if I misunderstand your point, please correct me. And > if you have any sage idea, please guide me. Something like this: clocks = <&clks 197>, <&clks 3>, <&clks 197>, <&clks 107>, <&clks SPDIF_EXT>, <&clks 118>, <&clks 62>, <&clks 139>, <&clks MLB_PHY> clock-names = "core", "rxtx0", "rxtx1", "rxtx2", "rxtx3", "rxtx4", "rxtx5", "rxtx6", "rxtx7" This describes the different input clocks to the spdif core and also gives a hint to the array index (rxtx_n_) to use. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |