linux-kernel - Re: [PATCH v3 2/2] Input: synaptics-rmi4 - add support for F34 device reflash

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Date:   Wed, 12 Oct 2016 19:57:05 +0100
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 v3 2/2] Input: synaptics-rmi4 - add support for F34
 device reflash

Hi Benjamin-

Thanks for the review, I've answered in line.

On Mon, Oct 10, 2016 at 03:48:07PM +0200, Benjamin Tissoires wrote:
> On Sep 20 2016 or thereabouts, Nick Dyer wrote:
> > 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 | 161 ++++++++++++++-
> >  drivers/input/rmi4/rmi_driver.h |   7 +
> >  drivers/input/rmi4/rmi_f01.c    |   6 +
> >  drivers/input/rmi4/rmi_f34.c    | 446 ++++++++++++++++++++++++++++++++++++++++
> >  include/linux/rmi.h             |   1 +
> >  8 files changed, 634 insertions(+), 2 deletions(-)
> >  create mode 100644 drivers/input/rmi4/rmi_f34.c
[...]
> > @@ -143,8 +154,11 @@ int rmi_process_interrupt_requests(struct rmi_device *rmi_dev)
> >  	struct rmi_function *entry;
> >  	int error;
> >  
> > -	if (!data)
> > +	mutex_lock(&data->irq_mutex);
> > +	if (!data || !data->irq_status || !data->f01_container) {
> > +		mutex_unlock(&data->irq_mutex);
> 
> I have been now convinced that IRQ should be handled in core. It would
> make everyone's life easier and I think means that we won't need these
> checks given that IRQ could simply be disabled during FW update.
> 
> I guess it's time to resurrect Bjorn's patch at
> https://lkml.org/lkml/2016/5/9/1055

We do use the interrupts in FW update in the current version. I haven't
done the measurements, but my expectation would be that performance is
slightly improved over polling, and it's more elegant.

> > +#ifdef CONFIG_RMI4_F34
> > +static int rmi_firmware_update(struct rmi_driver_data *data,
> > +			       const struct firmware *fw)
> > +{
> > +	struct device *dev = &data->rmi_dev->dev;
> > +	int ret;
> > +
> > +	if (!data->f34_container) {
> > +		dev_warn(dev, "%s: No F34 present!\n",
> > +			 __func__);
> > +		return -EINVAL;
> > +	}
> > +
> > +	ret = rmi_f34_check_supported(data->f34_container);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Enter flash mode */
> > +	rmi_dbg(RMI_DEBUG_CORE, dev, "Enabling flash\n");
> > +	ret = rmi_f34_enable_flash(data->f34_container);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Tear down functions and re-probe */
> > +	rmi_free_function_list(data->rmi_dev);
> > +
> > +	ret = rmi_probe_interrupts(data);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = rmi_init_functions(data);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (!data->f01_bootloader_mode || !data->f34_container) {
> > +		dev_warn(dev, "%s: No F34 present or not in bootloader!\n",
> > +			 __func__);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Perform firmware update */
> > +	ret = rmi_f34_update_firmware(data->f34_container, fw);
> > +
> > +	/* Re-probe */
> > +	rmi_dbg(RMI_DEBUG_CORE, dev, "Re-probing device\n");
> > +	rmi_free_function_list(data->rmi_dev);
> > +
> > +	ret = rmi_scan_pdt(data->rmi_dev, NULL, rmi_initial_reset);
> > +	if (ret < 0)
> > +		dev_warn(dev, "RMI reset failed!\n");
> > +
> > +	ret = rmi_probe_interrupts(data);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = rmi_init_functions(data);
> > +	if (ret)
> > +		return ret;
> 
> You could basically export rmi_fn_reset() which would call
> rmi_free_function_list(), rmi_scan_pdt (if initial reset),
> rmi_probe_interrupts() and rmi_init_functions, and this would allow you
> to have all this in f34.

I see what you mean, and I do agree that it would be neater to have all
of this in the f34 code.

However, the problem is that when you call rmi_free_function_list(), the
f34 driver and all the context information attached to it (struct
rmi_function, struct f34_data, and any sysfs attributes in the f34
directory) gets torn down, so you're kind of left without the branch you
were sitting on.

To get around that, I'd have to make f34 a special case anyway. Taking
that into account, the current solution seemed neater to me. I could
possibly cram a little more of it into rmi_f34.c, but I think the
context has to be "struct rmi_driver_data".

Nick