Re: [REGRESSION 7.3-rc1] HID: logitech-hidpp: hi-res scroll mode forcibly re-enabled on every reconnect for Bolt devices, overriding userspace

[Lovekesh Solanki]

On Sun, Sep 20, 2026 at 10:50:53PM +0200, Roman Stingler wrote:
> diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> index 1504de32b1c8..ffc7cef49b59 100644
> --- a/drivers/hid/hid-logitech-hidpp.c
> +++ b/drivers/hid/hid-logitech-hidpp.c
> @@ -2044,6 +2044,7 @@ static int hidpp_hrs_set_highres_scrolling_mode(struct hidpp_device *hidpp,
>  #define HIDPP_PAGE_HIRES_WHEEL		0x2121
>  
>  #define CMD_HIRES_WHEEL_GET_WHEEL_CAPABILITY	0x00
> +#define CMD_HIRES_WHEEL_GET_WHEEL_MODE		0x10
>  #define CMD_HIRES_WHEEL_SET_WHEEL_MODE		0x20
>  
>  static int hidpp_hrw_get_wheel_capability(struct hidpp_device *hidpp,
> @@ -2072,12 +2073,10 @@ static int hidpp_hrw_get_wheel_capability(struct hidpp_device *hidpp,
>  	return ret;
>  }
>  
> -static int hidpp_hrw_set_wheel_mode(struct hidpp_device *hidpp, bool invert,
> -	bool high_resolution, bool use_hidpp)
> +static int hidpp_hrw_get_wheel_mode(struct hidpp_device *hidpp, u8 *mode)
>  {
>  	u8 feature_index;
>  	int ret;
> -	u8 params[1];
>  	struct hidpp_report response;
>  
>  	ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_HIRES_WHEEL,
> @@ -2085,13 +2084,14 @@ static int hidpp_hrw_set_wheel_mode(struct hidpp_device *hidpp, bool invert,
>  	if (ret)
>  		return ret;
>  
> -	params[0] = (invert          ? BIT(2) : 0) |
> -		    (high_resolution ? BIT(1) : 0) |
> -		    (use_hidpp       ? BIT(0) : 0);
> +	ret = hidpp_send_fap_command_sync(hidpp, feature_index,
> +					  CMD_HIRES_WHEEL_GET_WHEEL_MODE,
> +					  NULL, 0, &response);
> +	if (ret)
> +		return ret;
>  
> -	return hidpp_send_fap_command_sync(hidpp, feature_index,
> -					   CMD_HIRES_WHEEL_SET_WHEEL_MODE,
> -					   params, sizeof(params), &response);
> +	*mode = response.fap.params[0];
> +	return 0;
>  }
>  
>  /* -------------------------------------------------------------------------- */
> @@ -3910,8 +3910,16 @@ static int hi_res_scroll_enable(struct hidpp_device *hidpp)
>  	u8 multiplier = 1;
>  
>  	if (hidpp->capabilities & HIDPP_CAPABILITY_HIDPP20_HI_RES_WHEEL) {
> -		ret = hidpp_hrw_set_wheel_mode(hidpp, false, true, false);
> -		if (ret == 0)
> +		u8 mode;
> +
> +		/*
> +		 * The wheel mode is persistent state in the device, so read it
> +		 * rather than overwriting it, and scale to match. A device
> +		 * left in hi-res still gets the multiplier it needs; one the
> +		 * user configured for low resolution is left alone.
> +		 */
> +		ret = hidpp_hrw_get_wheel_mode(hidpp, &mode);
> +		if (ret == 0 && (mode & BIT(1)))
>  			ret = hidpp_hrw_get_wheel_capability(hidpp, &multiplier);
>  	} else if (hidpp->capabilities & HIDPP_CAPABILITY_HIDPP20_HI_RES_SCROLL) {
>  		ret = hidpp_hrs_set_highres_scrolling_mode(hidpp, true,
> 
> Tested on top of 7.3-rc3, installed via DKMS so it is the module loaded at
> boot. Results against the same device:
> 
>                             stock   your patch   this
>   suspend/resume                no        yes       yes
>   solaar write sticks           no        yes       yes
>   module reload                 no        no        yes
>   cold boot                     no        no        yes

I didn't think of this, your patch seems like a better solution.
I think you should format and send it.


Regards,
Lovekesh