Re: [PATCH RESEND v6 1/5] hwmon: (pmbus/core): Add interrupt support

[Guenter Roeck]

On Tue, Jan 03, 2023 at 12:18:49PM +0530, Naresh Solanki wrote:
> Hi Guenter,
> 
> On 29-12-2022 08:10 pm, Guenter Roeck wrote:
> > On Wed, Dec 14, 2022 at 09:07:11AM +0100, Naresh Solanki wrote:
> > > From: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
> > > 
> > > Implement PMBUS irq handler.
> > > 
> > > Signed-off-by: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
> > > Signed-off-by: Naresh Solanki <Naresh.Solanki@xxxxxxxxxxxxx>
> > 
> > $ scripts/checkpatch.pl --strict index.html
> > CHECK: Blank lines aren't necessary after an open brace '{'
> > #131: FILE: drivers/hwmon/pmbus/pmbus_core.c:3088:
> > +	for (i = 0; i < data->info->pages; i++) {
> > +
> > 
> > CHECK: Alignment should match open parenthesis
> > #183: FILE: drivers/hwmon/pmbus/pmbus_core.c:3140:
> > +	ret = devm_request_threaded_irq(dev, client->irq, NULL, pmbus_fault_handler,
> > +			      0, "pmbus-irq", data);
> > 
> > CHECK: Please use a blank line after function/struct/union/enum declarations
> > #197: FILE: drivers/hwmon/pmbus/pmbus_core.c:3154:
> >   }
> > +static int pmbus_irq_setup(struct i2c_client *client, struct pmbus_data *data)
> > 
> > total: 0 errors, 0 warnings, 3 checks, 109 lines checked
> > 
> > NOTE: For some of the reported defects, checkpatch may be able to
> >        mechanically convert to the typical style using --fix or --fix-inplace.
> > 
> > index.html has style problems, please review.
> > 
> > Please run checkpatch --strict on your patches.
> > Also see Documentation/hwmon/submitting-patches.rst.
> I will take care of these errors in the updated version.
> > 
> > > ---
> > >   drivers/hwmon/pmbus/pmbus.h      |  2 +-
> > >   drivers/hwmon/pmbus/pmbus_core.c | 84 ++++++++++++++++++++++++++++++++
> > >   2 files changed, 85 insertions(+), 1 deletion(-)
> > > 
> > > 
> > > base-commit: 364ffd2537c44cb6914ff5669153f4a86fffad29
> > > 
> > > diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> > > index 10fb17879f8e..6b2e6cf93b19 100644
> > > --- a/drivers/hwmon/pmbus/pmbus.h
> > > +++ b/drivers/hwmon/pmbus/pmbus.h
> > > @@ -26,7 +26,7 @@ enum pmbus_regs {
> > >   	PMBUS_CAPABILITY		= 0x19,
> > >   	PMBUS_QUERY			= 0x1A,
> > > -
> > > +	PMBUS_SMBALERT_MASK		= 0x1B,
> > >   	PMBUS_VOUT_MODE			= 0x20,
> > >   	PMBUS_VOUT_COMMAND		= 0x21,
> > >   	PMBUS_VOUT_TRIM			= 0x22,
> > > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> > > index 95e95783972a..244fd2597252 100644
> > > --- a/drivers/hwmon/pmbus/pmbus_core.c
> > > +++ b/drivers/hwmon/pmbus/pmbus_core.c
> > > @@ -3072,11 +3072,89 @@ static int pmbus_regulator_register(struct pmbus_data *data)
> > >   	return 0;
> > >   }
> > > +
> > > +static int pmbus_write_smbalert_mask(struct i2c_client *client, u8 page, u8 reg, u8 val)
> > > +{
> > > +	return pmbus_write_word_data(client, page, PMBUS_SMBALERT_MASK, reg | (val << 8));
> > > +}
> > > +
> > > +static irqreturn_t pmbus_fault_handler(int irq, void *pdata)
> > > +{
> > > +	struct pmbus_data *data = pdata;
> > > +	struct i2c_client *client = to_i2c_client(data->dev);
> > > +	int i, status;
> > > +
> > > +	for (i = 0; i < data->info->pages; i++) {
> > > +
> > > +		mutex_lock(&data->update_lock);
> > > +		status = pmbus_read_status_word(client, i);
> > > +		if (status < 0) {
> > > +			mutex_unlock(&data->update_lock);
> > > +			return status;
> > > +		}
> > > +
> > > +		if (status & ~(PB_STATUS_OFF | PB_STATUS_BUSY | PB_STATUS_POWER_GOOD_N))
> > > +			pmbus_clear_fault_page(client, i);
> > > +
> > > +		mutex_unlock(&data->update_lock);
> > > +	}
> > > +
> > > +	return IRQ_HANDLED;
> > > +}
> > > +
> > > +static int pmbus_irq_setup(struct i2c_client *client, struct pmbus_data *data)
> > > +{
> > > +	struct device *dev = &client->dev;
> > > +	const struct pmbus_regulator_status_category *cat;
> > > +	const struct pmbus_regulator_status_assoc *bit;
> > > +	int i, j, err, ret, func;
> > > +	u8 mask;
> > > +
> > > +	for (i = 0; i < data->info->pages; i++) {
> > > +		func = data->info->func[i];
> > > +
> > > +		for (j = 0; j < ARRAY_SIZE(pmbus_regulator_flag_map); j++) {
> > > +			cat = &pmbus_regulator_flag_map[j];
> > > +			if (!(func & cat->func))
> > > +				continue;
> > > +			mask = 0;
> > > +			for (bit = cat->bits; bit->pflag; bit++)
> > > +				mask |= bit->pflag;
> > > +
> > > +			err = pmbus_write_smbalert_mask(client, i, cat->reg, ~mask);
> > > +			if (err)
> > > +				dev_err(dev, "Failed to set smbalert for reg 0x%02x\n",	cat->reg);
> > 
> > This concerns me. It might mean that the chip does not support
> > PMBUS_SMBALERT_MASK. If so, there would be lots of error messages.
> After going through the PMBus specification, it appears that this should not
> be an issue unless there is a violation of the specification.

PMBus chips have lots of issues which violate the specification.
Have a look at the various drivers and the workarounds implemented there.
You'll need to check if the command/register is supported before using it.
Also, if you want to keep the error message, make it dev_err_once().

Either case, an error is an error, not to be ignored. An error here
should result in an error abort.

> > 
> > > +		}
> > > +
> > > +		pmbus_write_smbalert_mask(client, i, PMBUS_STATUS_CML, 0xff);
> > > +		pmbus_write_smbalert_mask(client, i, PMBUS_STATUS_OTHER, 0xff);
> > > +		pmbus_write_smbalert_mask(client, i, PMBUS_STATUS_MFR_SPECIFIC, 0xff);
> > 
> > Why check the return value from pmbus_write_smbalert_mask above but not here ?
> Thank you for pointing out the oversight. I will make sure to include an
> error check at this point.
> > 
> > > +		if (data->info->func[i] & PMBUS_HAVE_FAN12)
> > > +			pmbus_write_smbalert_mask(client, i, PMBUS_STATUS_FAN_12, 0xff);
> > > +		if (data->info->func[i] & PMBUS_HAVE_FAN34)
> > > +			pmbus_write_smbalert_mask(client, i, PMBUS_STATUS_FAN_34, 0xff);
> > > +	}
> > > +
> > > +	/* Register notifiers - can fail if IRQ is not given */
> > 
> > The comment does not make sense. pmbus_irq_setup() is not called
> > if the interrupt "is not given".
> Yes. The comment here is not relevant and will be removed.
> > 
> > > +	ret = devm_request_threaded_irq(dev, client->irq, NULL, pmbus_fault_handler,
> > > +			      0, "pmbus-irq", data);
> > > +	if (ret) {
> > > +		dev_warn(dev, "IRQ disabled %d\n", ret);
> > 
> > This is not a warning, it is an error.
> Thank you for bringing this to my attention. I will make sure to update the
> code to reflect that this is an error.
> > 
> > > +		return ret;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >   #else
> > 
> > This is still in regulator code. I said several times that this is not
> > acceptable.
> Thank you for pointing out the mistake. I will make sure to correct this in
> the next revision.
> > 
> > >   static int pmbus_regulator_register(struct pmbus_data *data)
> > >   {
> > >   	return 0;
> > >   }
> > > +static int pmbus_irq_setup(struct i2c_client *client, struct pmbus_data *data)
> > > +{
> > > +	return 0;
> > > +}
> > >   #endif
> > >   static struct dentry *pmbus_debugfs_dir;	/* pmbus debugfs directory */
> > > @@ -3441,6 +3519,12 @@ int pmbus_do_probe(struct i2c_client *client, struct pmbus_driver_info *info)
> > >   	if (ret)
> > >   		return ret;
> > > +	if (client->irq > 0) {
> > > +		ret = pmbus_irq_setup(client, data);
> > > +		if (ret)
> > > +			return ret;
> > > +	}
> > > +
> > >   	ret = pmbus_init_debugfs(client, data);
> > >   	if (ret)
> > >   		dev_warn(dev, "Failed to register debugfs\n");
> 
> Thanks,
> Naresh