From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-db9lp0250.outbound.messaging.microsoft.com ([213.199.154.250]:20861 "EHLO db9outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759502Ab3HNI4i (ORCPT ); Wed, 14 Aug 2013 04:56:38 -0400 Date: Wed, 14 Aug 2013 16:48:02 +0800 From: Nicolin Chen Subject: Re: [PATCH v4 resent 1/2] ASoC: fsl: Add S/PDIF CPU DAI driver Message-ID: <20130814084801.GH31651@MrMyself> References: <51808310dd97d2a35a28766ed7309f269521cafd.1376309076.git.b42378@freescale.com> <20130814075017.GE2324@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20130814075017.GE2324@pengutronix.de> Sender: devicetree-owner@vger.kernel.org To: Sascha Hauer Cc: broonie@kernel.org, lars@metafoo.de, p.zabel@pengutronix.de, linuxppc-dev@lists.ozlabs.org, alsa-devel@alsa-project.org, devicetree@vger.kernel.org, timur@tabi.org, rob.herring@calxeda.com List-ID: 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. Thank you, Nicolin Chen