Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755936AbcKKGRz (ORCPT ); Fri, 11 Nov 2016 01:17:55 -0500 Received: from fllnx209.ext.ti.com ([198.47.19.16]:65461 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753265AbcKKGRx (ORCPT ); Fri, 11 Nov 2016 01:17:53 -0500 Subject: Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz To: John Syne References: <20161024060226.4170-1-mugunthanvnm@ti.com> <038C6B01-8443-4321-9C65-BAC4095237D3@gmail.com> <086ab2fa-63ee-c5ab-2715-b2efd78270d7@ti.com> <12725C92-9BB8-4F77-A7B4-F3C3DA9F8B0B@gmail.com> <20161025063847.GD8574@dell> <20161026084811.GI8574@dell> <30CF3CC1-A4F1-4C31-B51F-A1AB1D352AF5@gmail.com> CC: Lee Jones , "N, Mugunthan V" , "linux-iio@vger.kernel.org" , Tony Lindgren , Jonathan Cameron , "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "Nori, Sekhar" , "Ujfalusi, Peter" From: Vignesh R Message-ID: Date: Fri, 11 Nov 2016 11:47:19 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <30CF3CC1-A4F1-4C31-B51F-A1AB1D352AF5@gmail.com> 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 Content-Length: 2416 Lines: 57 On Friday 11 November 2016 09:00 AM, John Syne wrote: > >> On Nov 9, 2016, at 9:07 PM, Vignesh R wrote: >> >> Hi, >> >> On Thursday 10 November 2016 05:23 AM, John Syne wrote: >>> OK, then back to my original question. Given that these DT properties are supported in the driver >>> >> >> Below properties are supported by only by ti_am3335x_adc driver and not >> ti_am335x_tsc driver. As author of this patch pointed out in another >> reply, there is no need to change step-opendelay for tsc. AFAIK, I don't >> see a use case where these values needs to be tweaked for tsc channels, >> therefore it does not make sense to be DT properties. > Yeah, the confusion was mine because the author of this patch series was proposing to hard code these settings while DT properties already existed in the ti_am335x_adc driver. I use the ADC for sensor measurement and do not use the touchscreen features. I already pointed out where these DT parameters should be added by referencing how this was done in one of the BBB DT overlay files [1]. I am just proposing the same is done as a default in the AM33xx.dtsi and AM4372.dtsi files. Here is what I was proposing. > Granted, the adc-channels should be restricted to the subset of channels not used by tsc, but you get the idea. There are 4 wire, 5 wire and 8 wire touchscreens. Therefore there is no way to know in advance, how many channels are available for adc. IMO, this is not a SoC specific configuration but board dependent. Hence, all channel related configurations need to be in board specific dts files and not in top level dtsi files. > > tscadc: tscadc@44e0d000 { > compatible = "ti,am3359-tscadc"; > reg = <0x44e0d000 0x1000>; > interrupt-parent = <&intc>; > interrupts = <16>; > ti,hwmods = "adc_tsc"; > status = "disabled"; > dmas = <&edma 53 0>, <&edma 57 0>; > dma-names = "fifo0", "fifo1”; > > tsc { > compatible = "ti,am3359-tsc"; > }; > am335x_adc: adc { > #io-channel-cells = <1>; > ti,adc-channels = <0 1 2 3 4 5 6>; > ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>; > ti,chan-step-opendelay = <0x98 0x98 0x98 0x98 0x98 0x98 0x98>; > ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>; > compatible = "ti,am3359-adc"; > }; > }; > > [1]https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts > -- Regards Vignesh