From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vignesh R Subject: Re: [PATCH] input: ti_am335x_tsc: Add open delay parameter Date: Thu, 20 Aug 2015 17:41:30 +0530 Message-ID: <55D5C3F2.80900@ti.com> References: <1439318705-18601-1-git-send-email-mwelling@ieee.org> <55CAE71C.4060505@ti.com> <20150812184420.GA2442@deathstar> <20150819180835.GB29773@deathstar> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:55137 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751401AbbHTMLl (ORCPT ); Thu, 20 Aug 2015 08:11:41 -0400 In-Reply-To: <20150819180835.GB29773@deathstar> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Michael Welling Cc: Wolfram Sang , Dmitry Torokhov , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-input@vger.kernel.org" , Jonathan Cameron , "Griffis, Brad" On 08/19/2015 11:38 PM, Michael Welling wrote: > On Wed, Aug 12, 2015 at 01:44:22PM -0500, Michael Welling wrote: >> On Wed, Aug 12, 2015 at 11:56:36AM +0530, Vignesh R wrote: >>> Hi Michael, >>> >>> + Dmitry >>> >>> On 08/12/2015 12:15 AM, Michael Welling wrote: >>>> Adds a device tree parameter to set the open delay on the touchscreen >>>> conversion steps. Increasing this parameter helps the touch accuracy on >>>> some screens. >>>> >>>> Signed-off-by: Michael Welling >>>> --- >>>> .../bindings/input/touchscreen/ti-tsc-adc.txt | 5 +++++ >>>> drivers/input/touchscreen/ti_am335x_tsc.c | 18 ++++++++++++++---- >>>> 2 files changed, 19 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt >>>> index b1163bf..cb11fda 100644 >>>> --- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt >>>> +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt >>>> @@ -41,6 +41,11 @@ Optional properties: >>>> charge step, so this does in fact function as a >>>> hardware knob for adjusting the amount of "settling >>>> time". >>>> + ti,open-delay: Open delay applied to all touchscreen conversion steps. >>>> + The value corresponds to the number of ADC clock >>>> + cycles to wait after applying the step configuration >>>> + registers and before sending the start of ADC >>>> + conversion. Maximum value is 0x3FFFF. >>>> >>> >>> Since open-delay is per step, is it not better to allow specifying >>> open-delay per step like ti,chan-step-opendelay of adc? This will help >>> control open-delay for all the four wires. >> >> Do you see any reason why you would want a different delay for each step of >> the conversion on the same touchscreen? Sorry for the delay, I haven't seen different delays being used for different channels on 4-wire TSC ( not sure of 5-wire or 8 wire designs). Since this is DT change, I just wanted to make sure more flexibility is provided. >> >> The user would need to know the number of steps what each of the steps do. >> What I was thinking was making open-delay configurable per channel (one entry for X+, X-, Y+, Y-). For example, for a 4-wire TSC: ti,chan-open-delay = <0x30 0x100 0x20 0x10>; /* for X+, X-, Y+, Y- */ >>> >>>> - child "adc" >>>> ti,chan-step-opendelay: List of open delays for each channel of >>>> diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c >>>> index 191a1b8..37a9729 100644 >>>> --- a/drivers/input/touchscreen/ti_am335x_tsc.c >>>> +++ b/drivers/input/touchscreen/ti_am335x_tsc.c >>>> @@ -54,6 +54,7 @@ struct titsc { >>>> u32 inp_xp, inp_xn, inp_yp, inp_yn; >>>> u32 step_mask; >>>> u32 charge_delay; >>>> + u32 open_delay; >>>> }; >>>> >>>> static unsigned int titsc_readl(struct titsc *ts, unsigned int reg) >>>> @@ -148,7 +149,7 @@ static void titsc_step_config(struct titsc *ts_dev) >>>> end_step = first_step + tsc_steps; >>>> for (i = end_step - ts_dev->coordinate_readouts; i < end_step; i++) { >>>> titsc_writel(ts_dev, REG_STEPCONFIG(i), config); >>>> - titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY); >>>> + titsc_writel(ts_dev, REG_STEPDELAY(i), ts_dev->open_delay); >>>> } >>>> >>>> config = 0; >>>> @@ -172,7 +173,7 @@ static void titsc_step_config(struct titsc *ts_dev) >>>> end_step = first_step + ts_dev->coordinate_readouts; >>>> for (i = first_step; i < end_step; i++) { >>>> titsc_writel(ts_dev, REG_STEPCONFIG(i), config); >>>> - titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY); >>>> + titsc_writel(ts_dev, REG_STEPDELAY(i), ts_dev->open_delay); >>>> } >>>> >>>> /* Make CHARGECONFIG same as IDLECONFIG */ >>>> @@ -188,13 +189,13 @@ static void titsc_step_config(struct titsc *ts_dev) >>>> STEPCONFIG_INP(ts_dev->inp_xp); >>>> titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config); >>>> titsc_writel(ts_dev, REG_STEPDELAY(end_step), >>>> - STEPCONFIG_OPENDLY); >>>> + ts_dev->open_delay); >>>> >>>> end_step++; >>>> config |= STEPCONFIG_INP(ts_dev->inp_yn); >>>> titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config); >>>> titsc_writel(ts_dev, REG_STEPDELAY(end_step), >>>> - STEPCONFIG_OPENDLY); >>>> + ts_dev->open_delay); >>>> >>>> /* The steps end ... end - readouts * 2 + 2 and bit 0 for TS_Charge */ >>>> stepenable = 1; >>>> @@ -392,6 +393,15 @@ static int titsc_parse_dt(struct platform_device *pdev, >>>> dev_warn(&pdev->dev, "ti,charge-delay not specified\n"); >>>> } >>>> >>>> + err = of_property_read_u32(node, "ti,open-delay", >>>> + &ts_dev->open_delay); >>>> + /* >>>> + * If ti,open-delay value is not specified, then use >>>> + * STEPCONFIG_OPENDLY as the default value. >>>> + */ >>>> + if (err < 0) >>>> + ts_dev->open_delay = STEPCONFIG_OPENDLY; >>>> + >>>> return of_property_read_u32_array(node, "ti,wire-config", >>>> ts_dev->config_inp, ARRAY_SIZE(ts_dev->config_inp)); >>>> } >>>> >>> >>> -- >>> Regards >>> Vignesh -- Regards Vignesh