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authorPaul Cercueil <paul@crapouillou.net>2017-10-13 11:04:48 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2017-10-19 16:50:39 -0700
commit9b5db7aab4d6b66f84f5e147c87eff4fe8b48651 (patch)
tree01fd4f72856762bb98cd8b75ab4c774bf60a108d /drivers/input/input.c
parent481c209fa016a9e594427a306718cdf48ceeb1c6 (diff)
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Input: goodix - poll the 'buffer status' bit before reading data
The Goodix panel triggers an interrupt on touch events. However, its registers will contain the valid values a short time after the interrupt, and not when it's raised. At that moment, the 'buffer status' bit is set. Previously, if the 'buffer status' bit was not set when the registers were read, the data was discarded and no input event was emitted, causing "finger down" or "finger up" events to be missed sometimes. This went unnoticed until v4.9, as the DesignWare I2C driver commonly used with this driver had enough latency for that bug to never trigger until commit 2702ea7dbec5 ("i2c: designware: wait for disable/enable only if necessary"). Now, in the IRQ handler we will poll (with a timeout) the 'buffer status' bit and process the data of the panel as soon as this bit gets set. Note that the Goodix panel will send a few spurious interrupts after the 'finger up' event, in which the 'buffer status' bit will never be set. Cc: Bastien Nocera <hadess@hadess.net> Cc: russianneuromancer@ya.ru Signed-off-by: Paul Cercueil <paul@crapouillou.net> [hdegoede@redhat.com: Change poll loop to use jiffies, add comment about typical poll time] Signed-off-by: Hans de Goede <hdegoede@redhat.com> [dtor: rearranged control flow a bit to avoid explicit goto and double check] Reviewed-by: Bastien Nocera <hadess@hadess.net> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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