linux-kernel - Re: [PATCH v6 1/2] Input: synaptics-rmi4 - add support for F34 device reflash

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Date:   Wed, 23 Nov 2016 11:31:38 +0000
From:   Nick Dyer <nick@...anahar.org>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Andrew Duggan <aduggan@...aptics.com>,
        Chris Healy <cphealy@...il.com>,
        Henrik Rydberg <rydberg@...math.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/2] Input: synaptics-rmi4 - add support for F34
 device reflash

On Wed, Nov 23, 2016 at 12:20:41PM +0100, Benjamin Tissoires wrote:
> On Nov 20 2016 or thereabouts, Nick Dyer wrote:
> > Add support for updating firmware, triggered by a sysfs attribute.
> > 
> > This patch has been tested on Synaptics S7300.
> > 
> > Signed-off-by: Nick Dyer <nick@...anahar.org>
> > Tested-by: Chris Healy <cphealy@...il.com>
> > ---
> >  drivers/input/rmi4/Kconfig      |  11 +
> >  drivers/input/rmi4/Makefile     |   1 +
> >  drivers/input/rmi4/rmi_bus.c    |   3 +
> >  drivers/input/rmi4/rmi_driver.c | 105 ++++++---
> >  drivers/input/rmi4/rmi_driver.h |  24 ++
> >  drivers/input/rmi4/rmi_f01.c    |   6 +
> >  drivers/input/rmi4/rmi_f34.c    | 481 ++++++++++++++++++++++++++++++++++++++++
> >  drivers/input/rmi4/rmi_f34.h    |  68 ++++++
> >  include/linux/rmi.h             |   2 +
> >  9 files changed, 670 insertions(+), 31 deletions(-)
> >  create mode 100644 drivers/input/rmi4/rmi_f34.c
> >  create mode 100644 drivers/input/rmi4/rmi_f34.h
> > 
> > diff --git a/drivers/input/rmi4/Kconfig b/drivers/input/rmi4/Kconfig
> > index 8cbd362..9a24867 100644
> > --- a/drivers/input/rmi4/Kconfig
> > +++ b/drivers/input/rmi4/Kconfig
> > @@ -74,6 +74,17 @@ config RMI4_F30
> >  	  Function 30 provides GPIO and LED support for RMI4 devices. This
> >  	  includes support for buttons on TouchPads and ClickPads.
> >  
> > +config RMI4_F34
> > +	bool "RMI4 Function 34 (Device reflash)"
> > +	depends on RMI4_CORE
> > +	select FW_LOADER
> > +	help
> > +	  Say Y here if you want to add support for RMI4 function 34.
> > +
> > +	  Function 34 provides support for upgrading the firmware on the RMI4
> > +	  device via the firmware loader interface. This is triggered using a
> > +	  sysfs attribute.
> > +
> >  config RMI4_F54
> >  	bool "RMI4 Function 54 (Analog diagnostics)"
> >  	depends on RMI4_CORE
> > diff --git a/drivers/input/rmi4/Makefile b/drivers/input/rmi4/Makefile
> > index a6e2752..0250abf 100644
> > --- a/drivers/input/rmi4/Makefile
> > +++ b/drivers/input/rmi4/Makefile
> > @@ -7,6 +7,7 @@ rmi_core-$(CONFIG_RMI4_2D_SENSOR) += rmi_2d_sensor.o
> >  rmi_core-$(CONFIG_RMI4_F11) += rmi_f11.o
> >  rmi_core-$(CONFIG_RMI4_F12) += rmi_f12.o
> >  rmi_core-$(CONFIG_RMI4_F30) += rmi_f30.o
> > +rmi_core-$(CONFIG_RMI4_F34) += rmi_f34.o
> >  rmi_core-$(CONFIG_RMI4_F54) += rmi_f54.o
> >  
> >  # Transports
> > diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
> > index 84b3212..ef7a662 100644
> > --- a/drivers/input/rmi4/rmi_bus.c
> > +++ b/drivers/input/rmi4/rmi_bus.c
> > @@ -315,6 +315,9 @@ static struct rmi_function_handler *fn_handlers[] = {
> >  #ifdef CONFIG_RMI4_F30
> >  	&rmi_f30_handler,
> >  #endif
> > +#ifdef CONFIG_RMI4_F34
> > +	&rmi_f34_handler,
> > +#endif
> >  #ifdef CONFIG_RMI4_F54
> >  	&rmi_f54_handler,
> >  #endif
> > diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
> > index 4f8d197..2b17d8c 100644
> > --- a/drivers/input/rmi4/rmi_driver.c
> > +++ b/drivers/input/rmi4/rmi_driver.c
> > @@ -35,14 +35,24 @@
> >  #define RMI_DEVICE_RESET_CMD	0x01
> >  #define DEFAULT_RESET_DELAY_MS	100
> >  
> > -static void rmi_free_function_list(struct rmi_device *rmi_dev)
> > +void rmi_free_function_list(struct rmi_device *rmi_dev)
> >  {
> >  	struct rmi_function *fn, *tmp;
> >  	struct rmi_driver_data *data = dev_get_drvdata(&rmi_dev->dev);
> >  
> >  	rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev, "Freeing function list\n");
> >  
> > +	mutex_lock(&data->irq_mutex);
> 
> Sorry for coming late in the party, but now that I am rebasing my
> patches on top of Dmitry's branch, I realise that the mutex lock/unlock
> operations are just wrong now.
> 
> irq_mutex used to protect the irq_mask of struct rmi_driver_data and
> where only used sparsely by the .config call during reset. It was also
> used by rmi_process_interrupt_requests() in the IRQ handler, but the
> chances of the conflict where low. Side note, this should be a spinlock
> given that it can be called in an interrupt context.

Ack

> But with this patch, the mutex now serves as a barrier for IRQs. It is
> now taken by a lot of functions that can stall a lot, and so the IRQ
> will not be happy to be put to sleep.
> 
> Looking at the code, I realise that we should be able to avoid the whole
> locks by the firmware update if we simply disable/enable the interrupts
> before attempting the firmware update (in rmi_firmware_update()).
> 
> If you agree with the general idea, I can revert those locks and simply
> call enable_irq/disable_irq in a following patch.

I don't believe the firmware update will work without the interrupts
being enabled - it uses a completion:

http://git.kernel.org/cgit/linux/kernel/git/dtor/input.git/tree/drivers/input/rmi4/rmi_f34.c?h=synaptics-rmi4#n103

I would suggest that if this is a problem, we can change the F34 to not
use the interrupt and poll instead?

cheers

Nick