Message-ID: <fb9b4615-ecd9-d394-82d4-a1b9661be8f6@redhat.com>
Date:   Tue, 23 Mar 2021 21:03:57 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     "YingChieh, Ho" <andrea.cs97g@...u.edu.tw>
Cc:     platform-driver-x86@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Mark Gross <mgross@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Andrea Ho <andrea.ho@...antech.com.tw>
Subject: Re: [V2,1/1] platform/x86: add support for Advantech software defined
 button

Hi,

On 3/19/21 5:00 AM, YingChieh, Ho wrote:
> Hi Hans,
> 
> Thank you for your kindly review.
> As a beginner in driver coding, I got gains much from your suggestions.

I'm glad to hear that my reviews are helping you.

> Path v3 is ready at patchwork.^^

Thank you, I'll try to take a look at it soon.

Regards,

Hans


> 
> Hans de Goede <hdegoede@...hat.com> 於 2021年3月19日 週五 上午12:21寫道：
>>
>> Hi,
>>
>> On 3/12/21 9:11 AM, YingChieh Ho wrote:
>>> From: "Andrea.Ho" <Andrea.Ho@...antech.com.tw>
>>>
>>> Advantech sw_button is a ACPI event trigger button.
>>>
>>> With this driver, we can report KEY_EVENT on the
>>> Advantech Tabletop Network Appliances products and it has been
>>> tested in FWA1112VC.
>>>
>>> Add the software define button support to report EV_REP key_event
>>> (KEY_PROG1) by pressing button that cloud be get on user
>>> interface and trigger the customized actions.
>>>
>>> Signed-off-by: Andrea.Ho <Andrea.Ho@...antech.com.tw>
>>>
>>> v2:
>>>         - change evdev key-code from BTN_TRIGGER_HAPPY to KEY_PROG1
>>>         - to rewrite the driver to be a regular platform_driver
>>>         - use specific names instead of generic names,
>>>           "Software Button" to "Advantech Software Button",
>>>           "button" to "adv_swbutton"
>>>         - remove unused defines or use-once defines, ACPI_BUTTON_FILE_INFO,
>>>           ACPI_BUTTON_FILE_STATE, ACPI_BUTTON_TYPE_UNKNOWN, ACPI_SWBTN_NAME
>>
>> Thank you this version is much better, I have various review remarks below.
>>
>> Please send a v3 with those fixed.
>>
>>
>>> ---
>>>  MAINTAINERS                         |   5 +
>>>  drivers/platform/x86/Kconfig        |  11 ++
>>>  drivers/platform/x86/Makefile       |   3 +
>>>  drivers/platform/x86/adv_swbutton.c | 192 ++++++++++++++++++++++++++++
>>>  4 files changed, 211 insertions(+)
>>>  create mode 100644 drivers/platform/x86/adv_swbutton.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 68f21d46614c..e35c48e411b7 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -562,6 +562,11 @@ S: Maintained
>>>  F:     Documentation/scsi/advansys.rst
>>>  F:     drivers/scsi/advansys.c
>>>
>>> +ADVANTECH SWBTN DRIVER
>>> +M:     Andrea Ho <Andrea.Ho@...antech.com.tw>
>>> +S:     Maintained
>>> +F:     drivers/platform/x86/adv_swbutton.c
>>> +
>>>  ADXL34X THREE-AXIS DIGITAL ACCELEROMETER DRIVER (ADXL345/ADXL346)
>>>  M:     Michael Hennerich <michael.hennerich@...log.com>
>>>  S:     Supported
>>> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
>>> index 0581a54cf562..b1340135c5e9 100644
>>> --- a/drivers/platform/x86/Kconfig
>>> +++ b/drivers/platform/x86/Kconfig
>>> @@ -180,6 +180,17 @@ config ACER_WMI
>>>           If you have an ACPI-WMI compatible Acer/ Wistron laptop, say Y or M
>>>           here.
>>
>> This is supposed to be indented by a space (from the diff format) and then
>> a tab + 2 spaces, but in your patch this is now indented by 10 spaces.
>>
>> In general your entire patch has all tabs replaced by spaces, I guess that
>> your mail-client or editor is mangling things. Please do the following:
>>
>> 1. Check your patch for checkpatch errors:
>>
>> git format-patch HEAD~
>> scripts/checkpatch.pl 0001-platform...patch
>>
>> And fix all reported issues, both whitespace issues and others.
>>
>> 2. Send the next version of the patch like this:
>>
>> git format-patch -v3 HEAD~
>> git send-email v3-0001-platform...patch
>>
>> Do NOT edit the v3-0001-platform...patch file between these 2 steps.
>>
>>
>>> +config ADV_SWBUTTON
>>> +    tristate "Advantech ACPI Software Button Driver"
>>
>> You are using indent steps of 4 spaces here, that should be a tab
>>> +    depends on ACPI
>>> +    help
>>> +      Say Y here to enable support for Advantech software defined
>>> +      button feature. More information can be fount at
>>> +      <http://www.advantech.com.tw/products/>
>>
>> And a tab and 2 spaces for the help text.
>>
>>> +
>>> +      To compile this driver as a module, choose M here. The module will
>>> +      be called adv_swbutton.
>>> +
>>>  config APPLE_GMUX
>>>         tristate "Apple Gmux Driver"
>>>         depends on ACPI && PCI
>>> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
>>> index 2b85852a1a87..76a321fc58ba 100644
>>> --- a/drivers/platform/x86/Makefile
>>> +++ b/drivers/platform/x86/Makefile
>>> @@ -22,6 +22,9 @@ obj-$(CONFIG_ACERHDF)         += acerhdf.o
>>>  obj-$(CONFIG_ACER_WIRELESS)    += acer-wireless.o
>>>  obj-$(CONFIG_ACER_WMI)         += acer-wmi.o
>>>
>>> +# Advantech
>>> +obj-$(CONFIG_ADV_SWBUTTON)  += adv_swbutton.o
>>> +
>>
>> The indent before the += should use tabs not spaces.
>>
>>>  # Apple
>>>  obj-$(CONFIG_APPLE_GMUX)       += apple-gmux.o
>>>
>>> diff --git a/drivers/platform/x86/adv_swbutton.c
>>> b/drivers/platform/x86/adv_swbutton.c
>>> new file mode 100644
>>> index 000000000000..f4387220e8a0
>>> --- /dev/null
>>> +++ b/drivers/platform/x86/adv_swbutton.c
>>> @@ -0,0 +1,192 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + *  adv_swbutton.c - Software Button Interface Driver.
>>> + *
>>> + *  (C) Copyright 2020 Advantech Corporation, Inc
>>> + *
>>> + */
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/init.h>
>>> +#include <linux/version.h>
>>> +#include <linux/types.h>
>>> +#include <linux/proc_fs.h>
>>> +#include <linux/input.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/acpi.h>
>>> +#include <linux/platform_device.h>
>>> +#include <acpi/button.h>
>>> +#include <acpi/acpi_drivers.h>
>>
>> Please drop the following unused defines:
>>
>> #include <linux/init.h>
>> #include <linux/version.h>
>> #include <linux/types.h>
>> #include <linux/proc_fs.h>
>> #include <linux/slab.h>
>> #include <acpi/button.h>
>> #include <acpi/acpi_drivers.h>
>>
>> And sort the remaining includes alphabetically.
>>
>>> +
>>> +#define MODULE_NAME                         "adv_swbutton"
>>
>> Please drop this define, instead just set the .driver.name part of the platform_driver struct directly to "adv_swbutton".
>>
>>> +
>>> +#define ACPI_BUTTON_HID_SWBTN               "AHC0310"
>>> +#define ACPI_BUTTON_TYPE_SOFTWARE           0x07
>>
>> Please drop the ACPI_BUTTON_TYPE_SOFTWARE define.
>>
>>> +
>>> +#define ACPI_BUTTON_NOTIFY_SWBTN_RELEASE    0x86
>>> +#define ACPI_BUTTON_NOTIFY_SWBTN_PRESSED    0x85
>>> +
>>> +#define SOFTWARE_BUTTON                     KEY_PROG1
>>
>> Please drop this unnecessary define and just use KEY_PROG1 directly.
>>
>>> +
>>> +#define _COMPONENT                          ACPI_BUTTON_COMPONENT
>>> +
>>> +struct acpi_button {
>>
>> Please give this struct-type a different name, e.g. use:
>>
>> struct adv_swbutton {
>>
>>> +       unsigned int type;
>>
>> And drop the type here, it is always set to ACPI_BUTTON_TYPE_SOFTWARE, so it has no function.
>>
>>> +       struct input_dev *input;
>>> +       char phys[32];
>>> +       bool pressed;
>>
>> Also please drop the pressed bool, see below.
>>
>>
>>> +};
>>> +
>>> +/*-------------------------------------------------------------------------
>>> + *                               Driver Interface
>>> + *--------------------------------------------------------------------------
>>> + */
>>> +static void acpi_button_notify(acpi_handle handle, u32 event, void *context)
>>> +{
>>> +       struct acpi_device *device = context;
>>> +
>>> +       struct acpi_button *button = dev_get_drvdata(&device->dev);
>>
>> You must not call dev_set_drvdata on the acpi_device since you are not binding
>> to the acpi_device, you are binding to the platform_device, so set the drv_data
>> there and please don't touch the acpi_device.
>>
>>> +       struct input_dev *input;
>>> +
>>> +       int keycode, BTN_KEYCODE = SOFTWARE_BUTTON;
>>
>> Please drop these 3 variables, they are not necessary.
>>
>>> +
>>> +       switch (event) {
>>> +       case ACPI_BUTTON_NOTIFY_SWBTN_RELEASE:
>>> +               input = button->input;
>>
>> Just use button->input below instead of having this unnecessary
>> helper variable.
>>
>>> +
>>> +               if (!button->pressed)
>>> +                       return;
>>
>> This is not necessary, the input core takes care of not sending
>> events when the state does not change.
>>
>>> +
>>> +               keycode = test_bit(BTN_KEYCODE, input->keybit) ?
>>> +                               BTN_KEYCODE : KEY_UNKNOWN;
>>
>> No idea why you are doing this, but it is not necessary,
>> also it is wrong, you should be using KEY_PROG1 here.
>>
>>> +
>>> +               button->pressed = false;
>>
>> Keeping track of the pressed state is not necessary.
>>
>>> +
>>> +               input_report_key(input, keycode, 0);
>>> +               input_sync(input);
>>
>> Basically this entire case can be simplified to:
>>
>>        case ACPI_BUTTON_NOTIFY_SWBTN_RELEASE:
>>                input_report_key(button->input, KEY_PROG1, 0);
>>                input_sync(button->input);
>>                break;
>>
>>
>>> +       break;
>>
>> This break is indented wrong.
>>
>>> +       case ACPI_BUTTON_NOTIFY_SWBTN_PRESSED:
>>> +               input = button->input;
>>> +               button->pressed = true;
>>> +
>>> +               keycode = test_bit(BTN_KEYCODE, input->keybit) ?
>>> +                           BTN_KEYCODE : KEY_UNKNOWN;
>>> +
>>> +               input_report_key(input, keycode, 1);
>>> +               input_sync(input);
>>> +       break;
>>
>> And the same as above here, this can be simplified to:
>>
>>        case ACPI_BUTTON_NOTIFY_SWBTN_PRESSED:
>>                input_report_key(button->input, KEY_PROG1, 1);
>>                input_sync(button->input);
>>                break;
>>
>>
>>> +       default:
>>> +               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
>>> +                                 "Unsupported event [0x%x]\n", event));
>>
>> Please don't use ACPI_DEBUG_PRINTF outside of drivers/acpi, instead
>> use:
>>
>>                   dev_dbg(&platform_device->dev, ...);
>>
>>> +       break;
>>
>> There is no need for a break at the end of a switch-case
>>
>>> +       }
>>> +}
>>> +
>>> +static int acpi_button_probe(struct platform_device *device)
>>> +{
>>> +       struct acpi_device *acpi_device;
>>> +       struct acpi_button *button;
>>> +       struct input_dev *input;
>>> +       acpi_status status;
>>> +
>>> +       int error;
>>> +
>>> +       acpi_device = ACPI_COMPANION(&device->dev);
>>> +       if (!acpi_device) {
>>> +               dev_err(&device->dev, "ACPI companion is missing\n");
>>> +               return -ENOMEM;
>>> +       }
>>> +
>>> +       status = acpi_install_notify_handler(acpi_device->handle,
>>> +                                            ACPI_DEVICE_NOTIFY,
>>> +                                            acpi_button_notify,
>>> +                                            acpi_device);
>>> +       if (ACPI_FAILURE(status)) {
>>> +               dev_err(&device->dev, "Error installing notify handler\n");
>>> +               error = -ENODEV;
>>> +       }
>>
>> This needs to be done at the end of probe, if the notifier now runs, before
>> you have called dev_set_drvdata(), you will have a NULL pointer deref,
>> and even if the dev_set_drvdata() then the notifier may run before you have
>> set button->input = input and you still have a NULL pointer deref.
>>
>> So first setup everything and only then call acpi_install_notify_handler().
>>
>>> +
>>> +       button = devm_kzalloc(&acpi_device->dev, sizeof(*button), GFP_KERNEL);
>>> +       if (!button)
>>> +               return -ENOMEM;
>>> +
>>> +       dev_set_drvdata(&acpi_device->dev, button);
>>
>> Call this on the platform_device, so:
>>
>>        dev_set_drvdata(&device->dev, button);
>>
>> Also see above.
>>
>>> +
>>> +       input = devm_input_allocate_device(&acpi_device->dev);
>>> +       if (!input) {
>>> +               error =  -ENOMEM;
>>> +               goto err_free_mem;
>>
>> There is no need for the goto err_free_mem here (see below), so this
>> can be simplified to just:
>>
>>       input = devm_input_allocate_device(&acpi_device->dev);
>>       if (!input)
>>                return -ENOMEM;
>>
>>> +       }
>>> +
>>> +       button->input = input;
>>> +       button->type = ACPI_BUTTON_TYPE_SOFTWARE;
>>> +       button->pressed = false;
>>
>> Drop the setting of type/pressed, see above.
>>
>>
>>> +
>>> +       snprintf(button->phys, sizeof(button->phys),
>>> "%s/button/input0", ACPI_BUTTON_HID_SWBTN);
>>> +
>>> +       input->name = "Advantech Software Button";
>>> +       input->phys = button->phys;
>>> +       input->id.bustype = BUS_HOST;
>>> +       input->id.product = button->type;
>>
>> Don't set product to some semi-random value. Just leave it at 0.
>>
>>> +       input->dev.parent = &acpi_device->dev;
>>
>> This should be:
>>
>>         input->dev.parent = &device->dev;
>>
>>> +
>>> +       switch (button->type) {
>>> +       case ACPI_BUTTON_TYPE_SOFTWARE:
>>> +               set_bit(EV_KEY, input->evbit);
>>> +               set_bit(EV_REP, input->evbit);
>>> +
>>> +               input_set_capability(input, EV_KEY, SOFTWARE_BUTTON);
>>> +       break;
>>> +       }
>>
>> button->type always equals ACPI_BUTTON_TYPE_SOFTWARE, so you can drop the whole
>> switch-case here and input_set_capability(input, EV_KEY, ...) already does:
>> set_bit(EV_KEY, input->evbit);, so this entire block can be simplified to just:
>>
>>           set_bit(EV_REP, input->evbit);
>>           input_set_capability(input, EV_KEY, KEY_PROG1);
>>
>>
>>> +
>>> +       input_set_drvdata(input, acpi_device);
>>
>> You are never using the drvdata associated with the input_dev, so
>> this can be dropped. Also please don't use acpi_device for this/
>>
>>> +       error = input_register_device(input);
>>> +       if (error)
>>> +               return error;
>>> +
>>> +       device_init_wakeup(&acpi_device->dev, true);
>>
>> Don't use acpi_device, instead do:
>>
>>           device_init_wakeup(&device->dev, true);
>>
>>
>>
>>
>>> +
>>> +       return 0;
>>> +
>>> +err_free_mem:
>>> +       devm_kfree(&device->dev, button);
>>
>> devm_kzalloced mem will automatically be free-ed when the probe function
>> returns with an error, or when the driver is unbound (removed) so there
>> is no need to call devm_kfree() here.
>>
>>> +       return error;
>>> +}
>>> +
>>> +static int acpi_button_remove(struct platform_device *device)
>>> +{
>>> +       struct acpi_device *acpi_device = ACPI_COMPANION(&device->dev);
>>> +       struct acpi_button *button = dev_get_drvdata(&acpi_device->dev);
>>> +
>>> +       acpi_remove_notify_handler(acpi_device->handle, ACPI_DEVICE_NOTIFY,
>>> +                                  acpi_button_notify);
>>> +
>>> +       input_unregister_device(button->input);
>>> +       devm_kfree(&acpi_device->dev, button);
>>
>> The input_unregister_device() and devm_kfree() will be done automatically
>> when the remove function exits, so you can drop these 2 calls.
>>
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static const struct acpi_device_id button_device_ids[] = {
>>> +       {ACPI_BUTTON_HID_SWBTN, 0},
>>> +       {"", 0},
>>> +};
>>> +
>>> +MODULE_DEVICE_TABLE(acpi, button_device_ids);
>>> +
>>> +static struct platform_driver acpi_button_driver = {
>>> +       .driver = {
>>> +               .name = MODULE_NAME,
>>> +               .acpi_match_table = button_device_ids,
>>> +       },
>>> +       .probe = acpi_button_probe,
>>> +       .remove = acpi_button_remove,
>>> +};
>>> +
>>> +module_platform_driver(acpi_button_driver);
>>> +
>>
>> This is not an ACPI driver, please drop the ACPI_MODULE_NAME() call.
>>
>>> +ACPI_MODULE_NAME(MODULE_NAME);
>>> +
>>> +MODULE_AUTHOR("Andrea Ho");
>>> +MODULE_DESCRIPTION("Advantech ACPI SW Button Driver");
>>> +MODULE_LICENSE("GPL v2");
>>> --
>>> 2.17.1
>>>
>>
>> Regards,
>>
>> Hans
>>
> 

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