From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752100AbdI2KcU convert rfc822-to-8bit (ORCPT ); Fri, 29 Sep 2017 06:32:20 -0400 Received: from smtp.csie.ntu.edu.tw ([140.112.30.61]:41284 "EHLO smtp.csie.ntu.edu.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751852AbdI2KcS (ORCPT ); Fri, 29 Sep 2017 06:32:18 -0400 X-Google-Smtp-Source: AOwi7QA279wpLODBu1e7f4JYb+esDAGOsUjqqIj1poQ+9SuyHrGFcL+8g1T2ifnKMtPkFNVYDB00GAfETGOBHCgK6J0= MIME-Version: 1.0 In-Reply-To: <7F10060D-6A37-4417-9E24-1BB007580126@aosc.io> References: <20170928092543.45648-1-icenowy@aosc.io> <20170928092543.45648-2-icenowy@aosc.io> <20170928151103.ov3o5pn5h7inzzan@flea> <7F10060D-6A37-4417-9E24-1BB007580126@aosc.io> From: Chen-Yu Tsai Date: Fri, 29 Sep 2017 18:31:53 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [linux-sunxi] Re: [PATCH v2 1/3] ARM: dts: sun8i: Add basic dtsi file for Allwinner R40 To: Icenowy Zheng Cc: Maxime Ripard , Chen-Yu Tsai , devicetree , linux-arm-kernel , linux-kernel , linux-sunxi Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 29, 2017 at 6:25 PM, Icenowy Zheng wrote: > > > 于 2017年9月28日 GMT+08:00 下午11:11:03, Maxime Ripard 写到: >>Hi, >> >>On Thu, Sep 28, 2017 at 09:25:41AM +0000, Icenowy Zheng wrote: >>> + /* >>> + * The max-frequency properties in all MMC controller nodes >>> + * are conservative values proven to work on Banana Pi M2 >>> + * Ultra (the first community available R40 board). >>> + * As the board doesn't wire MMC3 out, the property is not >>> + * set in MMC3. >>> + * TODO: measure the accurate max frequency of the controllers. >>> + */ >>> + mmc0: mmc@1c0f000 { >>> + compatible = "allwinner,sun8i-r40-mmc", >>> + "allwinner,sun50i-a64-mmc"; >>> + reg = <0x01c0f000 0x1000>; >>> + clocks = <&ccu CLK_BUS_MMC0>, <&ccu CLK_MMC0>; >>> + clock-names = "ahb", "mmc"; >>> + resets = <&ccu RST_BUS_MMC0>; >>> + reset-names = "ahb"; >>> + pinctrl-0 = <&mmc0_pins>; >>> + pinctrl-names = "default"; >>> + interrupts = ; >>> + max-frequency = <25000000>; >>> + status = "disabled"; >>> + #address-cells = <1>; >>> + #size-cells = <0>; >>> + }; >> >>Sorry if it wasn't really clear, but my point was more than you should >>just drop the max-frequency property > > Then set it in the boards' DTS? Why do you need to set them in the first place? The higher speeds need voltage control, and the lack of said control means the system won't use them anyway. max-frequency would apply better in situations where the board layout can't guarantee proper signal propagation or timing beyond a certain frequency. Or if that particular controller instance is flawed or restricted in some way. ChenYu From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen-Yu Tsai Subject: Re: [linux-sunxi] Re: [PATCH v2 1/3] ARM: dts: sun8i: Add basic dtsi file for Allwinner R40 Date: Fri, 29 Sep 2017 18:31:53 +0800 Message-ID: References: <20170928092543.45648-1-icenowy@aosc.io> <20170928092543.45648-2-icenowy@aosc.io> <20170928151103.ov3o5pn5h7inzzan@flea> <7F10060D-6A37-4417-9E24-1BB007580126@aosc.io> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <7F10060D-6A37-4417-9E24-1BB007580126-h8G6r0blFSE@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Icenowy Zheng Cc: Maxime Ripard , Chen-Yu Tsai , devicetree , linux-arm-kernel , linux-kernel , linux-sunxi List-Id: devicetree@vger.kernel.org On Fri, Sep 29, 2017 at 6:25 PM, Icenowy Zheng wrote: > > > 于 2017年9月28日 GMT+08:00 下午11:11:03, Maxime Ripard 写到: >>Hi, >> >>On Thu, Sep 28, 2017 at 09:25:41AM +0000, Icenowy Zheng wrote: >>> + /* >>> + * The max-frequency properties in all MMC controller nodes >>> + * are conservative values proven to work on Banana Pi M2 >>> + * Ultra (the first community available R40 board). >>> + * As the board doesn't wire MMC3 out, the property is not >>> + * set in MMC3. >>> + * TODO: measure the accurate max frequency of the controllers. >>> + */ >>> + mmc0: mmc@1c0f000 { >>> + compatible = "allwinner,sun8i-r40-mmc", >>> + "allwinner,sun50i-a64-mmc"; >>> + reg = <0x01c0f000 0x1000>; >>> + clocks = <&ccu CLK_BUS_MMC0>, <&ccu CLK_MMC0>; >>> + clock-names = "ahb", "mmc"; >>> + resets = <&ccu RST_BUS_MMC0>; >>> + reset-names = "ahb"; >>> + pinctrl-0 = <&mmc0_pins>; >>> + pinctrl-names = "default"; >>> + interrupts = ; >>> + max-frequency = <25000000>; >>> + status = "disabled"; >>> + #address-cells = <1>; >>> + #size-cells = <0>; >>> + }; >> >>Sorry if it wasn't really clear, but my point was more than you should >>just drop the max-frequency property > > Then set it in the boards' DTS? Why do you need to set them in the first place? The higher speeds need voltage control, and the lack of said control means the system won't use them anyway. max-frequency would apply better in situations where the board layout can't guarantee proper signal propagation or timing beyond a certain frequency. Or if that particular controller instance is flawed or restricted in some way. ChenYu -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: wens@csie.org (Chen-Yu Tsai) Date: Fri, 29 Sep 2017 18:31:53 +0800 Subject: [linux-sunxi] Re: [PATCH v2 1/3] ARM: dts: sun8i: Add basic dtsi file for Allwinner R40 In-Reply-To: <7F10060D-6A37-4417-9E24-1BB007580126@aosc.io> References: <20170928092543.45648-1-icenowy@aosc.io> <20170928092543.45648-2-icenowy@aosc.io> <20170928151103.ov3o5pn5h7inzzan@flea> <7F10060D-6A37-4417-9E24-1BB007580126@aosc.io> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Sep 29, 2017 at 6:25 PM, Icenowy Zheng wrote: > > > ? 2017?9?28? GMT+08:00 ??11:11:03, Maxime Ripard ??: >>Hi, >> >>On Thu, Sep 28, 2017 at 09:25:41AM +0000, Icenowy Zheng wrote: >>> + /* >>> + * The max-frequency properties in all MMC controller nodes >>> + * are conservative values proven to work on Banana Pi M2 >>> + * Ultra (the first community available R40 board). >>> + * As the board doesn't wire MMC3 out, the property is not >>> + * set in MMC3. >>> + * TODO: measure the accurate max frequency of the controllers. >>> + */ >>> + mmc0: mmc at 1c0f000 { >>> + compatible = "allwinner,sun8i-r40-mmc", >>> + "allwinner,sun50i-a64-mmc"; >>> + reg = <0x01c0f000 0x1000>; >>> + clocks = <&ccu CLK_BUS_MMC0>, <&ccu CLK_MMC0>; >>> + clock-names = "ahb", "mmc"; >>> + resets = <&ccu RST_BUS_MMC0>; >>> + reset-names = "ahb"; >>> + pinctrl-0 = <&mmc0_pins>; >>> + pinctrl-names = "default"; >>> + interrupts = ; >>> + max-frequency = <25000000>; >>> + status = "disabled"; >>> + #address-cells = <1>; >>> + #size-cells = <0>; >>> + }; >> >>Sorry if it wasn't really clear, but my point was more than you should >>just drop the max-frequency property > > Then set it in the boards' DTS? Why do you need to set them in the first place? The higher speeds need voltage control, and the lack of said control means the system won't use them anyway. max-frequency would apply better in situations where the board layout can't guarantee proper signal propagation or timing beyond a certain frequency. Or if that particular controller instance is flawed or restricted in some way. ChenYu