Re: [PATCH v2 1/8] [PATCH 1/8] drivers/peci: Add support for PECI bus driver core

[Jae Hyun Yoo]

On 2/21/2018 1:51 PM, Andrew Lunn wrote:
> > > Is there a real need to do transfers in atomic context, or with
> > > interrupts disabled?
> >
> > Actually, no. Generally, this function will be called in sleep-able context
> > so this code is for an exceptional case handling.
> >
> > I'll rewrite this code like below:
> > 	if (in_atomic() || irqs_disabled()) {
> > 		dev_dbg(&adapter->dev,
> > 			"xfer in non-sleepable context is not supported\n");
> > 		return -EWOULDBLOCK;
> > 	}
>
> I would not even do that. Just add a call to
> might_sleep(). CONFIG_DEBUG_ATOMIC_SLEEP will then find bad calls.

Thanks for the suggestion. I've learned one thing. :)

> > > > +static int peci_ioctl_get_temp(struct peci_adapter *adapter, void *vmsg)
> > > > +{
> > > > +	struct peci_get_temp_msg *umsg = vmsg;
> > > > +	struct peci_xfer_msg msg;
> > > > +	int rc;
> > > > +
> > >
> > > Is this getting the temperature?
> >
> > Yes, this is getting the 'die' temperature of a processor package.
>   
> So the hwmon driver provides this. No need to have both.

This this common API in core driver of PECI bus. The hwmon is also uses 
it through peci_command call.

> > > > +static long peci_ioctl(struct file *file, unsigned int iocmd, unsigned long arg)
> > > > +{
> > > > +	struct peci_adapter *adapter = file->private_data;
> > > > +	void __user *argp = (void __user *)arg;
> > > > +	unsigned int msg_len;
> > > > +	enum peci_cmd cmd;
> > > > +	u8 *msg;
> > > > +	int rc = 0;
> > > > +
> > > > +	dev_dbg(&adapter->dev, "ioctl, cmd=0x%x, arg=0x%lx\n", iocmd, arg);
> > > > +
> > > > +	switch (iocmd) {
> > > > +	case PECI_IOC_PING:
> > > > +	case PECI_IOC_GET_DIB:
> > > > +	case PECI_IOC_GET_TEMP:
> > > > +	case PECI_IOC_RD_PKG_CFG:
> > > > +	case PECI_IOC_WR_PKG_CFG:
> > > > +	case PECI_IOC_RD_IA_MSR:
> > > > +	case PECI_IOC_RD_PCI_CFG:
> > > > +	case PECI_IOC_RD_PCI_CFG_LOCAL:
> > > > +	case PECI_IOC_WR_PCI_CFG_LOCAL:
> > > > +		cmd = _IOC_TYPE(iocmd) - PECI_IOC_BASE;
> > > > +		msg_len = _IOC_SIZE(iocmd);
> > > > +		break;
> > >
> > > Adding new ioctl calls is pretty frowned up. Can you export this info
> > > via /sysfs?
> >
> > Most of these are not simple IOs so ioctl is better suited, I think.
>
> Lets see what other reviewers say, but i think ioctls are
> wrong.
>
>       Andrew