[RFC] w1: regression, remove need for ida and use PLATFORM_DEVID_AUTO

[Andrew F. Davis]

On 02/01/2017 07:05 PM, Petr Cvek wrote:
> Patch 
> 	w1: remove need for ida and use PLATFORM_DEVID_AUTO
> 	098f9fb0c962eb2fdba5f9d34f4cf7a938237184 
> 
> causes a regression in the w1_ds2760 driver. Initialization creates a name "ds2760-battery.0.auto". It seems that name of that size will cause checking code in __thermal_cooling_device_register() from thermal_core.c to fail as it checks for names shorter than 20 chars:
> 
> 	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> 		return ERR_PTR(-EINVAL);
> 
> A second problem seems to be with magician_supplicants list as "ds2760-battery.0" does not match in a test power_supply_am_i_supplied() in ds2760_battery_update_status() from drivers/power/supply/ds2760_battery.c . This causes status flag to be forever in POWER_SUPPLY_STATUS_DISCHARGING state.
> 
> Functionality returned after I hotfix changed (drivers/w1/slaves/w1_ds2760.c)
> 
> 	pdev = platform_device_alloc("ds2760-battery", PLATFORM_DEVID_AUTO);
> 
> to
> 
> 	pdev = platform_device_alloc("ds2760-battery", 0);
> 
> Which solution do you advise. Shortening the name let's say just to "ds2760" (with changes to arch files, w1 files and supply files), increasing THERMAL_NAME_LENGTH to let's say 32 (I don't know if this doesn't break something other) or just reverting to the old behavior?
> 

If 20 is no longer the max thermal name then THERMAL_NAME_LENGTH should
be changed.

As for the couple boards hard-coding "ds2760-battery.0", this is a
problem that should be fix regardless of any fix we chose here as IDA is
not guaranteed to return 0, so the battery could just as easily be
called ds2760-battery.7. (I've had this discussion before as the N900
user-space also make this mistake).

Andrew

> Best regards,
> Petr
>