Re: [PATCH v2 07/11] input: macsmc-hid: New driver to handle the Apple Mac SMC buttons/lid

Dmitry Torokhov
2025-08-29T11:11:29Z

Hi James,

On Wed, Aug 27, 2025 at 09:22:41PM +1000, James Calligeros wrote:
> +static void macsmc_hid_event_button(struct macsmc_hid *smchid, unsigned long event)
> +{
> + u8 button = (event >> 8) & 0xff;
> + u8 state = !!(event & 0xff);
> +
> + switch (button) {
> + case BTN_POWER:
> + case BTN_TOUCHID:
> + if (smchid->wakeup_mode) {
> + if (state)
> + pm_wakeup_hard_event(smchid->dev);
> + } else {
> + input_report_key(smchid->input, KEY_POWER, state);
> + input_sync(smchid->input);
> + }

I believe you should be using pm_wakeup_event() in all cases so that
pressing power would interrupt suspend even if resume() handler has not
been run yet. Also I do not think suppressing KEY_POWER is needed.
Userspace should be smart and decide whether to shutdown the system or
not when receiving KEY_POWER depending on the overall system state.

...
> +
> +static int macsmc_hid_probe(struct platform_device *pdev)
> +{
> + struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
> + struct macsmc_hid *smchid;
> + bool have_lid, have_power;
> + int ret;

int error;

> +
> + /* Bail early if this SMC neither supports power button nor lid events */
> + have_lid = apple_smc_key_exists(smc, SMC_KEY(MSLD));
> + have_power = apple_smc_key_exists(smc, SMC_KEY(bHLD));
> + if (!have_lid && !have_power)
> + return -ENODEV;
> +
> + smchid = devm_kzalloc(&pdev->dev, sizeof(*smchid), GFP_KERNEL);
> + if (!smchid)
> + return -ENOMEM;
> +
> + smchid->dev = &pdev->dev;
> + smchid->smc = smc;
> + platform_set_drvdata(pdev, smchid);
> +
> + smchid->input = devm_input_allocate_device(&pdev->dev);
> + if (!smchid->input)
> + return -ENOMEM;
> +
> + smchid->input->phys = "macsmc-hid (0)";
> + smchid->input->name = "Apple SMC power/lid events";
> +
> + if (have_lid)
> + input_set_capability(smchid->input, EV_SW, SW_LID);
> + if (have_power)
> + input_set_capability(smchid->input, EV_KEY, KEY_POWER);
> +
> + ret = input_register_device(smchid->input);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to register input device: %d\n", ret);
> + return ret;
> + }
> +
> + if (have_lid) {
> + u8 val;
> +
> + ret = apple_smc_read_u8(smc, SMC_KEY(MSLD), &val);
> + if (ret < 0)
> + dev_warn(&pdev->dev, "Failed to read initial lid state\n");
> + else
> + input_report_switch(smchid->input, SW_LID, val);
> + }
> +
> + if (have_power) {
> + u32 val;
> +
> + ret = apple_smc_read_u32(smc, SMC_KEY(bHLD), &val);
> + if (ret < 0)
> + dev_warn(&pdev->dev, "Failed to read initial power button state\n");
> + else
> + input_report_key(smchid->input, KEY_POWER, val & 1);
> + }

Since you are doing this to seed initial switch/button state I would do
this before registering input device (this is safe to do so).

Thanks.

--
Dmitry