On Mon, 01 Jun 2020, Mark Pearson wrote:
> Newer Lenovo Thinkpad platforms have support to identify whether the
> system is on-lap or not using an ACPI DYTC event from the firmware.
>
> This patch provides the ability to retrieve the current mode via sysfs
> entrypoints and will be used by userspace for thermal mode and WWAN
> functionality
>
> Co-developed-by: Nitin Joshi <njoshi1@xxxxxxxxxx>
> Signed-off-by: Nitin Joshi <njoshi1@xxxxxxxxxx>
> Reviewed-by: Sugumaran <slacshiminar@xxxxxxxxxx>
> Signed-off-by: Mark Pearson <markpearson@xxxxxxxxxx>
We need to take this through the kernel platform-driver-x86 ML.
It would be nice to have standard events for "latop on a surface you
don't want to burn ("lap"), and the input people might want to suggest
something, too, so I'd also ask the input maintainer.
Please resend, cc to:
platform-driver-x86@xxxxxxxxxxxxxxx
While at it there is something I noticed right away:
> +static int dytc_command(int command)
> +{
> + acpi_handle dytc_handle;
> + int output;
> +
> + if (ACPI_FAILURE(acpi_get_handle(hkey_handle, "DYTC", &dytc_handle))) {
> + pr_warn("Thinkpad ACPI has no DYTC interface.\n");
> + return -ENODEV;
> + }
> + if (!acpi_evalf(dytc_handle, &output, NULL, "dd", command))
> + return -EIO;
> + return output;
> +}
dytc_command() is called by dytc_lapmode_get():
> +static int dytc_lapmode_get(void)
> +{
> + int output;
> +
> + output = dytc_command(DYTC_CMD_GET);
> + if ((output == -ENODEV) || (output == -EIO))
> + return output;
> +
> + return ((output >> DYTC_GET_LAPMODE_SHIFT) &
> + DYTC_GET_ENABLE_MASK);
> +}
Which is used by dytc_lapmode_init():
> +static int tpacpi_dytc_init(struct ibm_init_struct *iibm)
> +{
> + int res;
> +
> + dytc_available = false;
> + dytc_lapmode = dytc_lapmode_get();
> +
> + if (dytc_lapmode < 0 && dytc_lapmode != -ENODEV)
> + return dytc_lapmode;
> +
> + dytc_available = true;
> +
> + res = sysfs_create_group(&tpacpi_pdev->dev.kobj,
> + &dytc_attr_group);
> +
> + return res;
> +}
Looks like this code flow is going to spam people with pr_warn() on an
older thinkpad laptop that doesn't have DYTC. Please fix this, it is
not strange for an older thinkpad to not have DYTC (even if it is a
decade's old thinkpad).
There is a thinkpad-acpi driver-level debug facility you can use to send
developer-level debug info (such as the init function of a subdriver did
not find what it wanted), if you want.
Also, if the code flow goes through dytc_init fine and registers the
sub-driver, you likely don't have to optimize the rest of the code flow
for DYTC disappearing from APCI tables ;-) ENODEV silently would be
fine for something so unlikely to happen.
--
Henrique Holschuh
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