From: Aaron Ma <aaron.ma@canonical.com>
To: Christopher Heiny <Cheiny@synaptics.com>,
"dmitry.torokhov@gmail.com" <dmitry.torokhov@gmail.com>,
"linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andrew Duggan <aduggan@synaptics.com>,
"benjamin.tissoires@redhat.com" <benjamin.tissoires@redhat.com>
Subject: Re: [PATCH 1/2] Input: synaptics-rmi4 - clear irqs before set irqs
Date: Sat, 9 Mar 2019 16:37:33 +0800 [thread overview]
Message-ID: <a0f21198-5715-8858-8368-51e43092181e@canonical.com> (raw)
In-Reply-To: <17cd420ea32a9787c56ba25e36e7661541c2f65f.camel@synaptics.com>
Hi,
On 3/9/19 7:13 AM, Christopher Heiny wrote:
> I'm not sure this is a safe action, due to a race condition with the
> actual IRQ handler (rmi_process_interrupt_requests from rmi_driver.c).
> Remember that reading the IRQ status register clears all the IRQ bits.
> So you're faced with this possible scenario:
> - ATTN asserted, indicating new data in IRQ status register
> - rmi_driver_set_irq_bits called
> - rmi_driver_set_irq_bits reads IRQ status, clearing bits
> - rmi_process_interrupt_requests called
> - rmi_process_interrupt_request reads IRQ status, sees no
> bits set, nested IRQs are not handled
> This could lead to loss of data or inconsistent system state
> information. For example, a button up or down event may be lost, with
> consequent weird behavior by the user interface.
rmi_driver_set_irq_bits is only called to config and enable specific
functions of RMI.
Reading IRQ status before set irqs is supposed to clear spam data/irq
status.
spam data make probe/detect touchpad/trackpoint fail.
rmi_smb_resume -> rmi_driver_reset_handler -> fn-config ->
clear_irq_bits -> set_irq_bits -> enable_irq -> irq_handler ->
rmi_process_interrupt_requests
set_irq_bits will not be in interrupt context, it enables IRQ bits of RMI.
Regards,
Aaron
next prev parent reply other threads:[~2019-03-09 8:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 16:41 [PATCH 1/2] Input: synaptics-rmi4 - clear irqs before set irqs Aaron Ma
2019-02-20 16:42 ` [PATCH 2/2] Input: synaptics-rmi4 - export nosleep of f01 via sysfs Aaron Ma
2019-06-09 16:53 ` Dmitry Torokhov
2019-03-08 23:13 ` [PATCH 1/2] Input: synaptics-rmi4 - clear irqs before set irqs Christopher Heiny
2019-03-09 8:37 ` Aaron Ma [this message]
2019-03-28 6:02 ` Aaron Ma
2019-04-02 16:16 ` Christopher Heiny
2019-04-03 13:58 ` Aaron Ma
2019-06-04 2:45 ` Aaron Ma
2019-06-04 5:19 ` Christopher Heiny
2019-06-07 7:48 ` Aaron Ma
2019-06-09 16:55 ` Dmitry Torokhov
2019-06-10 16:55 ` Aaron Ma
2019-06-11 17:35 ` Dmitry Torokhov
2019-06-14 4:26 ` Aaron Ma
2019-11-19 5:34 ` Kai-Heng Feng
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