linux-kernel - RE: [PATCH] thermal: intel Quark SoC X1000 DTS thermal driver

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Date:	Mon, 23 Feb 2015 07:38:53 +0000
From:	"Kweh, Hock Leong" <hock.leong.kweh@...el.com>
To:	"Ong, Boon Leong" <boon.leong.ong@...el.com>,
	"Zhang, Rui" <rui.zhang@...el.com>,
	"edubezval@...il.com" <edubezval@...il.com>
CC:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Bryan O'Donoghue <pure.logic@...us-software.ie>
Subject: RE: [PATCH] thermal: intel Quark SoC X1000 DTS thermal driver

> -----Original Message-----
> From: Ong, Boon Leong
> Sent: Monday, February 23, 2015 9:39 AM
> Subject: RE: [PATCH] thermal: intel Quark SoC X1000 DTS thermal driver
> 
> >Just to bring out for discussion, do you think we should put a "safety range"
> >for reporting out the critical trip temperature value (mean the value from
> >register minus 1 or 2 degree)?
> >
> >Just wondering if this is needed for the software to have the sufficient
> >shutdown time before the HW make a hard power cut off when the
> >critical trip point is reached.
> 
> I assume that the suggestion is meant for the case where thermal register is
> not locked by BIOS. It is not a bad idea to have some protection against
> wrong configuration on critical trip point by user.
> Looking through the data-sheet in Quark, I could not find an recommended
> temperature. So, I propose that we use the same value set by BIOS today
> - 105C as the maximum.

What I mean here is that even the BIOS locks it and used the maximum value
105 °C for the critical trip point, should we -1 or -2 (104/103 °C) in this driver
to let the system shut down before the actual trip point hit, in case the HW
performs a HW power cut off before the Linux kernel has enough time to
shut down properly?

> 
> > > +static struct soc_sensor_entry *alloc_soc_dts(void)
> > > +{
> > > +	struct soc_sensor_entry *aux_entry;
> > > +	int err;
> > > +	u32 out;
> > > +	int wr_mask;
> > > +
> > > +	aux_entry = kzalloc(sizeof(*aux_entry), GFP_KERNEL);
> >
> >Wondering is it possible to use the resource-managed functions (for e.g.
> >devm_kzalloc())? This could help the driver looks more neat and clean
> >where the resource-managed framework will help you take care all the
> >kfree().
> >
> >Understand that the flow here is to call the thermal_zone_device_register()
> >function after this aux_entry allocation.
> >
> >But thinking would it also working if change the flow to call
> >thermal_zone_device_register() function 1st to obtain the
> >thermal_zone_device
> >then later on perform devm_kzalloc() and assign it back to devdata.
> >
> Ok, it is worth exploring on this devm_kzalloc() for neatness.
> Thanks!

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