linux-kernel - Re: [PATCH RFC] HID: cp2112: add IRQ chip handling

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Date:   Sat, 26 Nov 2016 22:57:10 +0100
From:   Antonio Borneo <borneo.antonio@...il.com>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Ellen Wang <ellen@...ulusnetworks.com>,
        David Barksdale <dbarksdale@...ogix.com>,
        Jiri Kosina <jikos@...nel.org>,
        linux-input <linux-input@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] HID: cp2112: add IRQ chip handling

On Mon, Nov 21, 2016 at 12:07 PM, Benjamin Tissoires
<benjamin.tissoires@...hat.com> wrote:
> The GPIO part doesn't provide interrupts when GPIO are toggled.
> So use a polling mechanism if someone requests a GPIO as an IRQ.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
>
> I am currently running this patch in my local tree.
> It allows to attach a SMBus device completely on the CP2112, with a simple
> definition at the end of probe:
>
>         {
>                 struct i2c_client *client;
>                 struct i2c_hid_platform_data pdata = {
>                         .hid_descriptor_address = 0x20,
>                 };
>                 struct i2c_board_info synaptics_info = {
>                         I2C_BOARD_INFO("hid", 0x2c),
>                         .platform_data = &pdata,
>                 };
>                 int irq = cp2112_allocate_irq(dev, 2);
>
>                 if (irq <= 0) {
>                         dev_err(dev->gc.parent, "Failed to translate GPIO to IRQ\n");
>                         goto err_sysfs_remove;
>                 }
>
>                 synaptics_info.irq = irq;
>                 irq_set_irq_type(irq, IRQ_TYPE_LEVEL_LOW);
>
>                 hid_device_io_start(hdev);
>
>                 /* give time for the device to initialize */
>                 msleep(500);
>
>                 client = i2c_new_device(&dev->adap, &synaptics_info);
>                 if (!client)
>                         hid_err(hdev, "failed allocating Synaptics device\n");
>
>         }
>
> I wonder if we want to consider this upstream, given that the driver is only
> used for development.

Ciao Benjamin,

for me it makes sense to push it upstream.
I also coded something similar 2+ years ago, but then my cp2112 got
broken before I could clean-up and submit the patches.
As far as I remember, Ellen was using cp2112 in a system in production.
For sure this driver is not widely used, but definitively it's not for
development use only.

Best Regards
Antonio