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Date: Tue, 11 Mar 2014 11:35:08 +0200 From: Roger Quadros <rogerq@...com> To: <balbi@...com> CC: Henrik Rydberg <rydberg@...omail.se>, <dmitry.torokhov@...il.com>, <jcbian@...cir.com.cn>, <dmurphy@...com>, <mugunthanvnm@...com>, <linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org> Subject: Re: [PATCH v2 4/8] Input: pixcir_i2c_ts: Use Type-B Multi-Touch protocol On 03/10/2014 06:37 PM, Felipe Balbi wrote: > On Mon, Mar 10, 2014 at 10:57:10AM +0200, Roger Quadros wrote: >> Hi Henrik, >> >> On 03/08/2014 05:11 PM, Henrik Rydberg wrote: >>> Hi Roger, >>> >>> the MT implementation seems mostly fine, just one curiosity: >>> >>>> static irqreturn_t pixcir_ts_isr(int irq, void *dev_id) >>>> { >>>> struct pixcir_i2c_ts_data *tsdata = dev_id; >>>> const struct pixcir_ts_platform_data *pdata = tsdata->chip; >>>> + struct pixcir_report_data report; >>>> >>>> while (!tsdata->exiting) { >>>> - pixcir_ts_poscheck(tsdata); >>>> - >>>> - if (gpio_get_value(pdata->gpio_attb)) >>>> + /* parse packet */ >>>> + pixcir_ts_parse(tsdata, &report); >>>> + >>>> + /* report it */ >>>> + pixcir_ts_report(tsdata, &report); >>>> + >>>> + if (gpio_get_value(pdata->gpio_attb)) { >>>> + if (report.num_touches) { >>>> + /* >>>> + * Last report with no finger up? >>>> + * Do it now then. >>>> + */ >>>> + input_mt_sync_frame(tsdata->input); >>>> + input_sync(tsdata->input); >>> >>> Why is this special handling needed? >> >> This is needed because the controller doesn't always report when all fingers >> have left the screen. e.g. report might contain 3 fingers touched and then >> gpio_attb line is de-asserted. There's no report with 0 fingers touched even >> if the user's fingers have left the screen. So we never detect a BUTTON_UP. >> >> Without this s/w workaround we observe side effects like buttons being pressed >> but not released. To me it looks like a bug in the controller. > > the other way would be to *also* use IRQF_TRIGGER_RISING, then you get > an IRQ when fingers leave the screen. No ? > Yes that is also possible but it involves an additional interrupt context switch. Sometimes the controller does report 0 finger touches before de-asserting the ATTB line and so this additional interrupt is not needed by the approach I used. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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