[{"id":1760773,"web_url":"http://patchwork.ozlabs.org/comment/1760773/","msgid":"","list_archive_url":null,"date":"2017-08-31T09:20:38","subject":"Re: [PATCHv3 3/5] dt-bindings: document the CEC GPIO bindings","submitter":{"id":7055,"url":"http://patchwork.ozlabs.org/api/people/7055/","name":"Linus Walleij","email":"linus.walleij@linaro.org"},"content":"On Wed, Aug 30, 2017 at 6:10 PM, Hans Verkuil wrote:\n\n> From: Hans Verkuil \n>\n> Document the bindings for the cec-gpio module for hardware where the\n> CEC pin and optionally the HPD pin are connected to GPIO pins.\n>\n> Signed-off-by: Hans Verkuil \n\nI usually refer to GPIO \"lines\" rather than \"pins\" for clarity.\nIt's because some systems also have pin control, and then it becomes\na bit muddy what is a pin.\n\n> +* HDMI CEC GPIO driver\n> +\n> +The HDMI CEC GPIO module supports CEC implementations where the CEC pin\n> +is hooked up to a pull-up GPIO pin and - optionally - the HPD pin is\n> +hooked up to a pull-down GPIO pin.\n> +\n> +Required properties:\n> + - compatible: value must be \"cec-gpio\"\n> + - cec-gpio: gpio that the CEC line is connected to\n> +\n> +Optional property:\n> + - hpd-gpio: gpio that the HPD line is connected to\n> +\n> +Example for the Raspberry Pi 3 where the CEC line is connected to\n> +pin 26 aka BCM7 aka CE1 on the GPIO pin header and the HPD line is\n> +connected to pin 11 aka BCM17:\n> +\n> +cec-gpio@7 {\n> + compatible = \"cec-gpio\";\n> + cec-gpio = <&gpio 7 GPIO_ACTIVE_HIGH>;\n> + hpd-gpio = <&gpio 17 GPIO_ACTIVE_HIGH>;\n> +};\n\nSo what I understood from the driver is that the cec-gpio is maybe actually\nan open drain output line, so in that case it should be stated in the docs and\ncec-gpio = <&gpio 7 GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN>\nor GPIO_LINE_OPEN_DRAIN if it is not also single-ended.\n\n\nYours,\nLinus Walleij\n--\nTo unsubscribe from this list: send the line \"unsubscribe devicetree\" in\nthe body of a message to majordomo@vger.kernel.org\nMore majordomo info at http://vger.kernel.org/majordomo-info.html","headers":{"Return-Path":"","X-Original-To":"incoming-dt@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming-dt@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; 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Thu,\n\t31 Aug 2017 02:20:38 -0700 (PDT)","MIME-Version":"1.0","In-Reply-To":"<20170830161044.26571-4-hverkuil@xs4all.nl>","References":"<20170830161044.26571-1-hverkuil@xs4all.nl>\n\t<20170830161044.26571-4-hverkuil@xs4all.nl>","From":"Linus Walleij ","Date":"Thu, 31 Aug 2017 11:20:38 +0200","Message-ID":"","Subject":"Re: [PATCHv3 3/5] dt-bindings: document the CEC GPIO bindings","To":"Hans Verkuil ","Cc":"\"linux-media@vger.kernel.org\" ,\n\t\"devicetree@vger.kernel.org\" ,\n\tHans Verkuil ,\n\t\"open list:DRM PANEL DRIVERS\" ","Content-Type":"text/plain; charset=\"UTF-8\"","Sender":"devicetree-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"devicetree@vger.kernel.org"}},{"id":1760817,"web_url":"http://patchwork.ozlabs.org/comment/1760817/","msgid":"","list_archive_url":null,"date":"2017-08-31T10:31:13","subject":"Re: [PATCHv3 3/5] dt-bindings: document the CEC GPIO bindings","submitter":{"id":723,"url":"http://patchwork.ozlabs.org/api/people/723/","name":"Hans Verkuil","email":"hverkuil@xs4all.nl"},"content":"On 31/08/17 11:20, Linus Walleij wrote:\n> On Wed, Aug 30, 2017 at 6:10 PM, Hans Verkuil wrote:\n> \n>> From: Hans Verkuil \n>>\n>> Document the bindings for the cec-gpio module for hardware where the\n>> CEC pin and optionally the HPD pin are connected to GPIO pins.\n>>\n>> Signed-off-by: Hans Verkuil \n> \n> I usually refer to GPIO \"lines\" rather than \"pins\" for clarity.\n> It's because some systems also have pin control, and then it becomes\n> a bit muddy what is a pin.\n\nI'll change the terminology.\n\n>> +* HDMI CEC GPIO driver\n>> +\n>> +The HDMI CEC GPIO module supports CEC implementations where the CEC pin\n>> +is hooked up to a pull-up GPIO pin and - optionally - the HPD pin is\n>> +hooked up to a pull-down GPIO pin.\n>> +\n>> +Required properties:\n>> + - compatible: value must be \"cec-gpio\"\n>> + - cec-gpio: gpio that the CEC line is connected to\n>> +\n>> +Optional property:\n>> + - hpd-gpio: gpio that the HPD line is connected to\n>> +\n>> +Example for the Raspberry Pi 3 where the CEC line is connected to\n>> +pin 26 aka BCM7 aka CE1 on the GPIO pin header and the HPD line is\n>> +connected to pin 11 aka BCM17:\n>> +\n>> +cec-gpio@7 {\n>> + compatible = \"cec-gpio\";\n>> + cec-gpio = <&gpio 7 GPIO_ACTIVE_HIGH>;\n>> + hpd-gpio = <&gpio 17 GPIO_ACTIVE_HIGH>;\n>> +};\n> \n> So what I understood from the driver is that the cec-gpio is maybe actually\n> an open drain output line, so in that case it should be stated in the docs and\n> cec-gpio = <&gpio 7 GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN>\n> or GPIO_LINE_OPEN_DRAIN if it is not also single-ended.\n\nYes, I agree, it's open drain. I'm not sure whether or not it is single-ended.\nI'm not sure what the difference is, and I have no electronics background.\n\nLooking at fwnode_get_named_gpiod() it seems that it has to be single-ended\nfor GPIO_OPEN_DRAIN to be set, so I am going with that. It works, so it is\nprobably right :-)\n\nRegards,\n\n\tHans\n--\nTo unsubscribe from this list: send the line \"unsubscribe devicetree\" in\nthe body of a message to majordomo@vger.kernel.org\nMore majordomo info at http://vger.kernel.org/majordomo-info.html","headers":{"Return-Path":"","X-Original-To":"incoming-dt@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming-dt@bilbo.ozlabs.org","Authentication-Results":"ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=devicetree-owner@vger.kernel.org; receiver=)","Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3xjdvY1B4zz9sQl\n\tfor ;\n\tThu, 31 Aug 2017 20:31:21 +1000 (AEST)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1751301AbdHaKbT (ORCPT\n\t);\n\tThu, 31 Aug 2017 06:31:19 -0400","from lb2-smtp-cloud9.xs4all.net ([194.109.24.26]:52007 \"EHLO\n\tlb2-smtp-cloud9.xs4all.net\" rhost-flags-OK-OK-OK-OK)\n\tby vger.kernel.org with ESMTP id S1751127AbdHaKbS (ORCPT\n\t); Thu, 31 Aug 2017 06:31:18 -0400","from [192.168.1.10] ([80.101.105.217])\n\tby smtp-cloud9.xs4all.net with ESMTPA\n\tid nMkjdVWDidRLjnMkkdH4k5; Thu, 31 Aug 2017 12:31:17 +0200"],"Subject":"Re: [PATCHv3 3/5] dt-bindings: document the CEC GPIO bindings","To":"Linus Walleij ","References":"<20170830161044.26571-1-hverkuil@xs4all.nl>\n\t<20170830161044.26571-4-hverkuil@xs4all.nl>\n\t","Cc":"\"linux-media@vger.kernel.org\" ,\n\t\"devicetree@vger.kernel.org\" ,\n\tHans Verkuil ,\n\t\"open list:DRM PANEL DRIVERS\" ","From":"Hans Verkuil ","Message-ID":"","Date":"Thu, 31 Aug 2017 12:31:13 +0200","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101\n\tThunderbird/45.7.1","MIME-Version":"1.0","In-Reply-To":"","Content-Type":"text/plain; charset=utf-8","Content-Transfer-Encoding":"7bit","X-CMAE-Envelope":"MS4wfLuoNjYd8kf1Os5l8/YsZ9uB291erpaBEyKI6AR7yYZV65oKAQkX4sY//wn3DRLJ1s7Vomfqma/zC0do4Bm4PpbDqRlFp86gVsEYOu7MYTx2ogyiIxrQ\n\tzSCfT+O8DIHyfzSAnOTILnLuy+ZUdhC5i9L+GmOMVYe0pLNR5Tg6dSjrFChzx22H8niB/LkqCWStQ0LaYZ5LyDjKUQ2uqhKloAwNmznWACtOQmRsWakUgBrb\n\t7Z0n+uGZLyXTkcztvE83rfwqXC72F8IDJyqPEr0kQxohRRiwFsJaD1Zx3JjS1yn8nDeBa+vRsQ2s4qiP2pr524nqu/wF8VZnYAt4bCtMq0Y=","Sender":"devicetree-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"devicetree@vger.kernel.org"}}]