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    SubjectRe: [PATCH RESEND v11] platform/chrome: Add ChromeOS ACPI device driver
    Hi Andy,

    Thank you for reviewing.

    On 5/10/22 2:33 PM, Andy Shevchenko wrote:
    > On Tue, May 10, 2022 at 8:44 AM Muhammad Usama Anjum
    > <usama.anjum@collabora.com> wrote:
    >>
    >> From: Enric Balletbo i Serra <enric.balletbo@collabora.com>
    >>
    >> The x86 Chromebooks have the ChromeOS ACPI device. This driver attaches
    >> to the ChromeOS ACPI device and exports the values reported by ACPI in a
    >> sysfs directory. This data isn't present in ACPI tables when read
    >> through ACPI tools, hence a driver is needed to do it. The driver gets
    >> data from firmware using the ACPI component of the kernel. The ACPI values
    >> are presented in string form (numbers as decimal values) or binary
    >> blobs, and can be accessed as the contents of the appropriate read only
    >> files in the standard ACPI device's sysfs directory tree. This data is
    >> consumed by the ChromeOS user space.
    >
    >> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
    >> Cc: Hans de Goede <hdegoede@redhat.com>
    >
    > You can use --cc parameter to `git send-email` instead of putting
    > these lines in the commit message.
    >
    > ...
    >
    >> +#define DEV_ATTR(_var, _name) \
    >> + static struct device_attribute dev_attr_##_var = \
    >> + __ATTR(_name, 0444, chromeos_first_level_attr_show, NULL);
    >> +
    >
    > Why not ATTR_RO()?
    It'll not work as attribute name has . in it.

    >
    > ...
    >
    >> +#define GPIO_ATTR_GROUP(_group, _name, _num) \
    >> + static umode_t attr_is_visible_gpio_##_num(struct kobject *kobj, \
    >> + struct attribute *attr, int n) \
    >> + { \
    >> + if (_num < chromeos_acpi_gpio_groups) \
    >> + return attr->mode; \
    >
    >> + else \
    >
    > Redundant.
    We are deciding on run time that how many GPIO attribute groups need to
    be shown. chromeos_acpi_gpio_groups is set at run time. I don't see why
    `else` can be redundant here.

    >
    >> + return 0; \
    >> + } \
    >> + static ssize_t chromeos_attr_show_gpio_##_num(struct device *dev, \
    >> + struct device_attribute *attr, \
    >> + char *buf) \
    >> + { \
    >> + char name[ACPI_ATTR_NAME_LEN + 1]; \
    >> + int ret, num; \
    >> + \
    >> + ret = parse_attr_name(attr->attr.name, name, &num); \
    >> + if (ret) \
    >> + return ret; \
    >
    >> + ret = chromeos_acpi_evaluate_method(dev, _num, num, name, buf); \
    >> + if (ret < 0) \
    >> + ret = 0; \
    >
    > Below I saw the same code, why is the error ignored?
    >
    I'll return the error in both places.

    >> + return ret; \
    >> + } \
    >> + static struct device_attribute dev_attr_0_##_group = \
    >> + __ATTR(GPIO.0, 0444, chromeos_attr_show_gpio_##_num, NULL); \
    >> + static struct device_attribute dev_attr_1_##_group = \
    >> + __ATTR(GPIO.1, 0444, chromeos_attr_show_gpio_##_num, NULL); \
    >> + static struct device_attribute dev_attr_2_##_group = \
    >> + __ATTR(GPIO.2, 0444, chromeos_attr_show_gpio_##_num, NULL); \
    >> + static struct device_attribute dev_attr_3_##_group = \
    >> + __ATTR(GPIO.3, 0444, chromeos_attr_show_gpio_##_num, NULL); \
    >> + \
    >> + static struct attribute *attrs_##_group[] = { \
    >> + &dev_attr_0_##_group.attr, \
    >> + &dev_attr_1_##_group.attr, \
    >> + &dev_attr_2_##_group.attr, \
    >> + &dev_attr_3_##_group.attr, \
    >> + NULL \
    >> + }; \
    >> + static const struct attribute_group attr_group_##_group = { \
    >> + .name = _name, \
    >> + .is_visible = attr_is_visible_gpio_##_num, \
    >
    >> + .attrs = attrs_##_group \
    >
    > Keep a comma here.
    Is there any particular reason for it? If there is, I'll add commas to
    all the structures.
    ...
    >
    > ...
    >
    >> +static int parse_attr_name(const char *name, char *attr_name, int *attr_num)
    >> +{
    >> + int ret = 0;
    >> +
    >> + strscpy(attr_name, name, ACPI_ATTR_NAME_LEN + 1);
    >> +
    >> + if (strlen(name) > ACPI_ATTR_NAME_LEN)
    >
    > This seems strange, esp. taking into account that strscpy() returns that.
    >
    > int ret;
    >
    > ret = strscpy(...);
    > if (ret == -E2BIG)
    > return kstrtoint(...);
    >
    > return 0;
    This is very nice way to do it. I'll update.
    ...

    --
    Muhammad Usama Anjum

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