Hi Nitin,
On 2/12/21 6:58 AM, Nitin Joshi wrote:
> Some newer Thinkpads have the WLAN antenna placed close to the WWAN
> antenna. In these cases FCC certification requires that when WWAN is
> active we reduce WLAN transmission power. A new Dynamic Power
> Reduction Control (DPRC) method is available from the BIOS on these
> platforms to reduce or restore WLAN Tx power.
>
> This patch provides a sysfs interface that userspace can use to adjust the
> WLAN power appropriately.
>
> Reviewed-by: Mark Pearson
> Signed-off-by: Nitin Joshi
This patch as well as patch 2/2 generally look ok to me.
The one thing which stands out is the:
*wlan_txreduce = -1;
Resp:
*wwan_antennatype = -1;
default:
return sysfs_emit(buf, "unknown type\n");
Bits, which Barnabás already pointed out.
If you can prepare a v2 of this patch-set addressing all the
review remarks which you have received so far then that
would be great.
Regards,
Hans
> ---
> .../admin-guide/laptops/thinkpad-acpi.rst | 18 +++
> drivers/platform/x86/thinkpad_acpi.c | 136 ++
> 2 files changed, 154 insertions(+)
>
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index 5fe1ade88c17..10410811b990 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -51,6 +51,7 @@ detailed description):
> - UWB enable and disable
> - LCD Shadow (PrivacyGuard) enable and disable
> - Lap mode sensor
> + - WLAN transmission power control
>
> A compatibility table by model and feature is maintained on the web
> site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1447,6 +1448,23 @@ they differ between desk and lap mode.
> The property is read-only. If the platform doesn't have support the sysfs
> class is not created.
>
> +WLAN transmission power control
> +
> +
> +sysfs: wlan_tx_strength_reduce
> +
> +Some newer Thinkpads have the WLAN antenna placed close to the WWAN antenna.
> +This interface will be used by userspace to reduce the WLAN Tx power strength
> +when WWAN is active, as is required for FCC certification.
> +
> +The available commands are::
> +
> +echo '0' >
> /sys/devices/platform/thinkpad_acpi/wlan_tx_strength_reduce
> +echo '1' >
> /sys/devices/platform/thinkpad_acpi/wlan_tx_strength_reduce
> +
> +The first command restores the wlan transmission power and the latter one
> +reduces wlan transmission power.
> +
> EXPERIMENTAL: UWB
> -
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c
> b/drivers/platform/x86/thinkpad_acpi.c
> index f3e8eca8d86d..6dbbd4a14264 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -9983,6 +9983,138 @@ static struct ibm_struct proxsensor_driver_data = {
> .exit = proxsensor_exit,
> };
>
> +/*
> + * DPRC(Dynamic Power Reduction Control) subdriver, for the Lenovo WWAN
> + * and WLAN feature.
> + */
> +#define DPRC_GET_WLAN_STATE 0x2
> +#define DPRC_SET_WLAN_POWER_REDUCE 0x00030010
> +#define DPRC_SET_WLAN_POWER_FULL0x00030100
> +static int has_wlantxreduce;
> +static int wlan_txreduce;
> +
> +static int dprc_command(int command, int *output)
> +{
> + acpi_handle dprc_handle;
> +
> + if (ACPI_FAILURE(acpi_get_handle(hkey_handle, "DPRC", &dprc_handle))) {
> + /* Platform doesn't support DPRC */
> + return -ENODEV;
> + }
> +
> + if (!acpi_evalf(dprc_handle, output, NULL, "dd", command))
> + return -EIO;
> +
> + /*
> + * METHOD_ERR gets returned on devices where few commands are not
> supported
> + * for example WLAN power reduce command is not supported on some
> devices.
> + */
> + if (*output & METHOD_ERR)
> + return -ENODEV;
> +
> + return 0;
> +}
> +
> +static int get_wlan_state(int *has_wlantxreduce, int *wlan_txreduce)
> +{
> + int output, err;
> +
> + /* Get current WLAN Power Transmission state */
> + err = dprc_command(DPRC_GET_WLAN_STATE, &output);
> + if (err)
> + return err;
> +
> + if (output & BIT(4))
> + *wlan_txreduce = 1;
> + else if (output & BIT(8))
> + *wlan_txreduce = 0;
> + else
> + *wlan_txreduce = -1;
> +
> + *has_wlantxreduce = 1;
> + return 0;
> +}
> +
> +/* sysfs wlan entry */
> +static ssize_t wlan_tx_strength_reduce_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + int err;
> +
> + err = get_wlan_state(&has_wlantxreduce, &wlan_txreduce);
> + if (err)
> + return err;
> +
> + return sysfs_emit(buf,
