Re: [PATCH] dell-smm-hwmon.c: Add XPS 9570 to supported devices list

[Guenter Roeck <linux@roeck-us.net>]

On Fri, Nov 30, 2018 at 03:44:08PM +0000, Michele Sorcinelli wrote:
> Reviewed by: Pali Rohár <pali.rohar@gmail.com>
> 

This is not where to put a Reviewed-by: tag, and the patch is
not signed and thus can not be applied.

> Allow the module to be loaded on Dell XPS 9570, without having to use
> the "force=1" option. The module loads without problems, and reports
> correct values:
> 
>     $ time cat /proc/i8k
>     1.0 1.5 -1 35 0 0 0 0 -1 -22
>     cat /proc/i8k  0.00s user 0.00s system 7% cpu 0.033 total
> 
> However, the call may freeze the kernel for a very small time due to
> code running in the SSM layer. This is a known issue with the driver, and
> can be reproduced with other supported models. Average execution
> time is 33 ms.

Is it ? My understanding is that it is an issue with the SMM layer.
If you have actual evidence that the problem lies within the driver,
not with SMM, please share that information.

> 
> The command line tools from i8kutils can properly set the fan speed,
> although the firmware will override it, unless automatic fan
> control is disabled with the proper SSM call.
> 
> Average fans speed (when firwmare automatic control is off):
> 
> STATE -> RPM
> 0 0 -> 0 0
> 1 1 -> 2500 2500
> 2 2 -> 5100 5100
> 3 3 -> same as 2 2
> 
> The SSM procedures I8K_SMM_GET_FAN_TYPE and I8K_SMM_GET_TEMP_TYPE are
> failing to return valid values to the module, that can't label the fans
> and initialize the temperature sensors in the hwmon interface.
> 
> This is a problem in the firmware code, and may be eventually addressed
> by a new firmware version.
> 
>     $ sensors dell_smm-virtual-0
>     dell_smm-virtual-0
>     Adapter: Virtual device
>     fan1:        2531 RPM
>     fan2:        2496 RPM
> 
> However, the procedures I8K_SMM_GET_FAN and I8K_SMM_GET_TEMP are working
> properly, as they return correct values. This means that the module
> could be modified to initialize the sensors without labels and report
> correct temperatures.

This is a different problem, not part of this patch, and the information
does not belong here.

Guenter

> ---
>  drivers/hwmon/dell-smm-hwmon.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
> index 9d3ef879d..367a8a617 100644
> --- a/drivers/hwmon/dell-smm-hwmon.c
> +++ b/drivers/hwmon/dell-smm-hwmon.c
> @@ -1017,6 +1017,13 @@ static const struct dmi_system_id i8k_dmi_table[] __initconst = {
>  			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 15 9560"),
>  		},
>  	},
> +	{
> +		.ident = "Dell XPS 15 9570",
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 15 9570"),
> +		},
> +	},
>  	{ }
>  };
>  
> -- 
> 2.19.2
>