Message-ID: <B9057989-C564-4B74-91E5-E23245B7D686@live.com>
Date: Wed, 3 Jul 2024 16:50:28 +0000
From: Aditya Garg <gargaditya08@...e.com>
To: Benjamin Tissoires <bentiss@...nel.org>
CC: Jiri Kosina <jikos@...nel.org>, Orlando Chamberlain
	<orlandoch.dev@...il.com>, "linux-input@...r.kernel.org"
	<linux-input@...r.kernel.org>, Linux Kernel Mailing List
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] HID: apple: Add support for magic keyboard backlight
 on T2 Macs


Hi Benjamin

> On 3 Jul 2024, at 7:38 PM, Benjamin Tissoires <bentiss@...nel.org> wrote:
> 
> On Jul 03 2024, Aditya Garg wrote:
>> From: Orlando Chamberlain <orlandoch.dev@...il.com>
>> 
>> Unlike T2 Macs with Butterfly keyboard, who have their keyboard backlight
>> on the USB device the T2 Macs with Magic keyboard have their backlight on
>> the Touchbar backlight device (05ac:8102).
>> 
>> Support for Butterfly keyboards has already been added in 9018eacbe623
>> ("HID: apple: Add support for keyboard backlight on certain T2 Macs.").
>> This patch adds support for the Magic keyboards.
>> 
>> Co-developed-by: Aditya Garg <gargaditya08@...e.com>
>> Signed-off-by: Aditya Garg <gargaditya08@...e.com>
>> Signed-off-by: Orlando Chamberlain <orlandoch.dev@...il.com>
> 
> Nitpick: the ordering of the signed-off is weird. It should be in order
> of persons who touched this driver.
> 
> Given that the From is Orlando and Aditya is submitting, I would have
> expected Orlando, then Aditya…
> 

Will fix this.

>> ---
>> drivers/hid/hid-apple.c | 87 ++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 86 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
>> index bd022e004356..2d1cd4456303 100644
>> --- a/drivers/hid/hid-apple.c
>> +++ b/drivers/hid/hid-apple.c
>> @@ -8,6 +8,8 @@
>>  *  Copyright (c) 2006-2007 Jiri Kosina
>>  *  Copyright (c) 2008 Jiri Slaby <jirislaby@...il.com>
>>  *  Copyright (c) 2019 Paul Pawlowski <paul@...rm.io>
>> + *  Copyright (c) 2023 Orlando Chamberlain <orlandoch.dev@...il.com>
>> + *  Copyright (c) 2024 Aditya Garg <gargaditya08@...e.com>
>>  */
>> 
>> /*
>> @@ -23,6 +25,7 @@
>> #include <linux/timer.h>
>> #include <linux/string.h>
>> #include <linux/leds.h>
>> +#include <dt-bindings/leds/common.h>
>> 
>> #include "hid-ids.h"
>> 
>> @@ -37,13 +40,18 @@
>> #define APPLE_NUMLOCK_EMULATION BIT(8)
>> #define APPLE_RDESC_BATTERY BIT(9)
>> #define APPLE_BACKLIGHT_CTL BIT(10)
>> -#define APPLE_IS_NON_APPLE BIT(11)
>> +#define APPLE_MAGIC_BACKLIGHT BIT(11)
>> +#define APPLE_IS_NON_APPLE BIT(12)
> 
> Please keep existing quirks definition in place, it adds noise for
> nothing in the patch. Also, technically, these quirks are used in
> .driver_data so they are uapi.
> 

Sure

>> 
>> #define APPLE_FLAG_FKEY 0x01
>> 
>> #define HID_COUNTRY_INTERNATIONAL_ISO 13
>> #define APPLE_BATTERY_TIMEOUT_MS 60000
>> 
>> +#define HID_USAGE_MAGIC_BL 0xff00000f
>> +#define APPLE_MAGIC_REPORT_ID_POWER 3
>> +#define APPLE_MAGIC_REPORT_ID_BRIGHTNESS 1
>> +
>> static unsigned int fnmode = 3;
>> module_param(fnmode, uint, 0644);
>> MODULE_PARM_DESC(fnmode, "Mode of fn key on Apple keyboards (0 = disabled, "
>> @@ -81,6 +89,12 @@ struct apple_sc_backlight {
>> struct hid_device *hdev;
>> };
>> 
>> +struct apple_magic_backlight {
>> + struct led_classdev cdev;
>> + struct hid_report *brightness;
>> + struct hid_report *power;
>> +};
>> +
>> struct apple_sc {
>> struct hid_device *hdev;
>> unsigned long quirks;
>> @@ -822,6 +836,66 @@ static int apple_backlight_init(struct hid_device *hdev)
>> return ret;
>> }
>> 
>> +static void apple_magic_backlight_report_set(struct hid_report *rep, s32 value, u8 rate)
>> +{
>> + rep->field[0]->value[0] = value;
>> + rep->field[1]->value[0] = 0x5e; /* Mimic Windows */
>> + rep->field[1]->value[0] |= rate << 8;
>> +
>> + hid_hw_request(rep->device, rep, HID_REQ_SET_REPORT);
>> +}
>> +
>> +static void apple_magic_backlight_set(struct apple_magic_backlight *backlight,
>> +      int brightness, char rate)
>> +{
>> + apple_magic_backlight_report_set(backlight->power, brightness ? 1 : 0, rate);
>> + if (brightness)
>> + apple_magic_backlight_report_set(backlight->brightness, brightness, rate);
>> +}
>> +
>> +static int apple_magic_backlight_led_set(struct led_classdev *led_cdev,
>> +  enum led_brightness brightness)
>> +{
>> + struct apple_magic_backlight *backlight = container_of(led_cdev,
>> + struct apple_magic_backlight, cdev);
>> +
>> + apple_magic_backlight_set(backlight, brightness, 1);
>> + return 0;
>> +}
>> +
>> +static int apple_magic_backlight_init(struct hid_device *hdev)
>> +{
>> + struct apple_magic_backlight *backlight;
>> +
>> + /*
>> +  * Ensure this usb endpoint is for the keyboard backlight, not touchbar
>> +  * backlight.
>> +  */
>> + if (hdev->collection[0].usage != HID_USAGE_MAGIC_BL)
>> + return -ENODEV;
>> +
>> + backlight = devm_kzalloc(&hdev->dev, sizeof(*backlight), GFP_KERNEL);
>> + if (!backlight)
>> + return -ENOMEM;
>> +
>> + backlight->brightness = hid_register_report(hdev, HID_FEATURE_REPORT,
>> + APPLE_MAGIC_REPORT_ID_BRIGHTNESS, 0);
>> + backlight->power = hid_register_report(hdev, HID_FEATURE_REPORT,
>> + APPLE_MAGIC_REPORT_ID_POWER, 0);
>> +
>> + if (!backlight->brightness || !backlight->power)
>> + return -ENODEV;
>> +
>> + backlight->cdev.name = ":white:" LED_FUNCTION_KBD_BACKLIGHT;
>> + backlight->cdev.max_brightness = backlight->brightness->field[0]->logical_maximum;
> 
> This is weird: a few lines above, you register a new report with
> hid_register_report() and now you are directly accessing
> field[0]->logical_maximum in that new report, which should be set to 0.
> 
> Unless you are using hid_register_report() to retrieve an existing
> report, which is bending the API a bit but is OK, but you should at
> least check that report->size is > 0 (and put a comment that the reports
> exist already).
> 
> (or do what is done in apple_fetch_battery() to retrieve the current
> report)
> 

Instead of 

	if (!backlight->brightness || !backlight->power)
		return -ENODEV;

Should I do (will all proper whitespace and line formatting):

	if (!backlight->brightness ||
             backlight->brightness->size == 0 ||
            !backlight->power ||
             backlight->power->size == 0)
		return -ENODEV;

> 
>> + backlight->cdev.brightness_set_blocking = apple_magic_backlight_led_set;
>> +
>> + apple_magic_backlight_set(backlight, 0, 0);
>> +
>> + return devm_led_classdev_register(&hdev->dev, &backlight->cdev);
>> +
>> +}
>> +
>> static int apple_probe(struct hid_device *hdev,
>> const struct hid_device_id *id)
>> {
>> @@ -860,6 +934,15 @@ static int apple_probe(struct hid_device *hdev,
>> if (quirks & APPLE_BACKLIGHT_CTL)
>> apple_backlight_init(hdev);
>> 
>> + if (quirks & APPLE_MAGIC_BACKLIGHT) {
>> + ret = apple_magic_backlight_init(hdev);
>> + if (ret) {
>> + del_timer_sync(&asc->battery_timer);
>> + hid_hw_stop(hdev);
>> + return ret;
> 
> Instead of manually unwind the probe in each sub-quirk, please add a new
> goto label and do goto out_err;

You mean this?:

	if (quirks & APPLE_MAGIC_BACKLIGHT) {
		ret = apple_magic_backlight_init(hdev);
		if (ret)
			goto out_err;
	}

	return 0;

out_err:
	del_timer_sync(&asc->battery_timer);
	hid_hw_stop(hdev);
	return ret;
}


> 
>> + }
>> + }
>> +
>> return 0;
>> }
>> 
>> @@ -1073,6 +1156,8 @@ static const struct hid_device_id apple_devices[] = {
>> .driver_data = APPLE_HAS_FN | APPLE_ISO_TILDE_QUIRK | APPLE_RDESC_BATTERY },
>> { HID_BLUETOOTH_DEVICE(BT_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MAGIC_KEYBOARD_NUMPAD_2021),
>> .driver_data = APPLE_HAS_FN | APPLE_ISO_TILDE_QUIRK },
>> + { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT),
>> + .driver_data = APPLE_MAGIC_BACKLIGHT },
>> 
>> { }
>> };
>> -- 
>> 2.45.2
>> 
> 
> Other than those few nitpicks, patch looks good. Please roll a v3 and
> I'll apply it.
> 
> Cheers,
> Benjamin

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