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Message-ID: <CAJqQiD39b=n-Lsza_YUPQR2jm49a3ZLxT-x7eYUv=yhD4fiDJQ@mail.gmail.com>
Date: Wed, 24 Aug 2022 13:58:33 +0800
From: Duke Du <dukedu83@...il.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: jdelvare@...e.com, corbet@....net, linux-hwmon@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
fran.hsu@...ntatw.com, charles.hsu@...ntatw.com,
george.hung@...ntatw.com, duke.du@...ntatw.com
Subject: Re: [PATCH v3] hwmon: Add driver for the TEXAS TPS546D24 Buck Converter.
Hi Guenter,
Thanks for your reply !
But I have some confusion as following, please help to give me some feedback.
Thanks a lot !
On Fri, Aug 19, 2022 at 9:35 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> On Fri, Aug 19, 2022 at 11:04:43AM +0800, Duke Du wrote:
> > Add the pmbus driver for TEXAS tps546d24 Buck Converter. The
> > tps546d24 PMBUS_VOUT_MODE is 0x97 (i.e. the bit 5~7 are 100)
> > which could not meet the standard pmbus spec, the standard mode
> > of PMBUS_VOUT_MODE must be 000 (linear foramt) or 001 (vid format).
> > Make the tps546d24 PMBUS_VOUT_MODE return value 0x17 (i.e. the
> > bit5~7 are 000), VOUT returned value is linear11.
> >
>
> First of all, the above should be documented as comment in the
> implementation.
>
> Second, this is actually problematic. In PMBus version 1.3.1, bit
> 7 of PMBUS_VOUT_MODE no longer describes the mode (linear, vid, direct,
> IEEE) but Absolute vs/ Relative VOUT voltages. This affects vout fault
> and warning limits. If the relative mode bit is set, those limits
> are supposed to reflect percentages, not absolute voltages.
>
> This means that the driver interprets vout voltage limits wrongly,
> at least if the chip works as described in the datasheet. Changing
> the reported value of PMBUS_VOUT_MODE is actually counter-productive.
>
> This means we'll need a number of changes. At the very least, the
> PMBus core needs to be be modified to only use bit 5 and 6 to determine
> the mode. On top of that, the driver probe function should update
> VOUT_MODE and clear bit 7. It might also make sense to warn in the
> PMBus core if mode bit 7 is set.
>
When the vout mode bit 7 is set, we update vout mode and clear bit 7
in the driver probe function, this operation is the same as changing
the reported value of PMBUS_VOUT_MODE ?
Maybe I misunderstood, could you please help to explain clearly about this ?
Thanks again for your help :)
Thanks,
Duke
> An alternative to the second change would be to implement relative
> vout support in the PMBus core, but that would be much more complex.
> We could also clear the relative bit in the PMBus core, but that might
> lead to unexpected side effects (we don't know how various chips
> respond to that) and thus probably not be a good idea.
>
> > Signed-off-by: Duke Du <Duke.Du@...ntatw.com>
>
> This e-mail address does not match the e-mail address used to send
> the patch, resulting in a checkpatch warning. Please fix.
>
> More comments inline.
>
> Thanks,
> Guenter
>
> > ---
> > Change in v1:
> > Initial patchset.
> > Change in v2:
> > Correct the tps546d24.rst format.
> > Change in v3:
> > 1. Modify the patch description.
> > 2. Put the change log between the dashes and diffstat.
> > ---
> > ---
> > Documentation/hwmon/index.rst | 1 +
> > Documentation/hwmon/tps546d24.rst | 35 +++++++++++++++++++
> > MAINTAINERS | 7 ++++
> > drivers/hwmon/pmbus/Kconfig | 9 +++++
> > drivers/hwmon/pmbus/Makefile | 1 +
> > drivers/hwmon/pmbus/tps546d24.c | 73 +++++++++++++++++++++++++++++++++++++++
> > 6 files changed, 126 insertions(+)
> > create mode 100644 Documentation/hwmon/tps546d24.rst
> > create mode 100644 drivers/hwmon/pmbus/tps546d24.c
> >
> > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> > index f7113b0..d3eede4 100644
> > --- a/Documentation/hwmon/index.rst
> > +++ b/Documentation/hwmon/index.rst
> > @@ -205,6 +205,7 @@ Hardware Monitoring Kernel Drivers
> > tps23861
> > tps40422
> > tps53679
> > + tps546d24
> > twl4030-madc-hwmon
> > ucd9000
> > ucd9200
> > diff --git a/Documentation/hwmon/tps546d24.rst b/Documentation/hwmon/tps546d24.rst
> > new file mode 100644
> > index 0000000..3061fd8
> > --- /dev/null
> > +++ b/Documentation/hwmon/tps546d24.rst
> > @@ -0,0 +1,35 @@
> > +.. SPDX-License-Identifier: GPL-2.0-only
> > +
> > +Kernel driver tps546d24
> > +======================
> > +
> > +Supported chips:
> > +
> > + * TI TPS546D24
> > +
> > + Prefix: 'tps546d24'
> > +
> > + Addresses scanned: -
> > +
> > + Datasheet: https://www.ti.com/lit/gpn/tps546d24
> > +
> > +Author: Duke Du <dukedu83@...il.com>
>
> This needs to match Author and Signed-off-by:. This applies to all
> e-mail addresses.
>
> > +
> > +
> > +Description
> > +-----------
> > +
> > +The TPS546D24A is a highly integrated, non-isolated DC/DC converter capable
> > +of high frequency operation and 40-A current output from a 7-mm x 5-mm
> > +package.
> > +
> > +Two, three, and four TPS546D24A devices can be interconnected
> > +to provide up to 160 A on a single output. The device has an option to
> > +overdrive the internal 5-V LDO with an external 5-V supply via the VDD5
> > +pin to improve efficiency and reduce power dissipation of the converter.
> > +
> > +
> > +Platform data support
> > +---------------------
> > +
> > +The driver supports standard PMBus driver platform data.
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 8a5012b..fa2d4fb 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -20583,6 +20583,13 @@ Q: https://patchwork.kernel.org/project/linux-integrity/list/
> > T: git git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git
> > F: drivers/char/tpm/
> >
> > +TPS546D24 DRIVER
> > +M: Duke Du <dukedu83@...il.com>
> > +L: linux-hwmon@...r.kernel.org
> > +S: Maintained
> > +F: Documentation/hwmon/tps546d24.rst
> > +F: drivers/hwmon/pmbus/tps546d24.c
> > +
> > TRACING
> > M: Steven Rostedt <rostedt@...dmis.org>
> > M: Ingo Molnar <mingo@...hat.com>
> > diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> > index 951e4a9..89668af 100644
> > --- a/drivers/hwmon/pmbus/Kconfig
> > +++ b/drivers/hwmon/pmbus/Kconfig
> > @@ -397,6 +397,15 @@ config SENSORS_TPS53679
> > This driver can also be built as a module. If so, the module will
> > be called tps53679.
> >
> > +config SENSORS_TPS546D24
> > + tristate "TPS546D24"
> > + help
> > + If you say yes here you get hardware monitoring support for TEXAS
> > + TPS546D24.
> > +
> > + This driver can also be built as a module. If so, the module will
> > + be called tps546d24
> > +
> > config SENSORS_UCD9000
> > tristate "TI UCD90120, UCD90124, UCD90160, UCD90320, UCD9090, UCD90910"
> > help
> > diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> > index e2fe86f..0002dbe 100644
> > --- a/drivers/hwmon/pmbus/Makefile
> > +++ b/drivers/hwmon/pmbus/Makefile
> > @@ -41,6 +41,7 @@ obj-$(CONFIG_SENSORS_Q54SJ108A2) += q54sj108a2.o
> > obj-$(CONFIG_SENSORS_STPDDC60) += stpddc60.o
> > obj-$(CONFIG_SENSORS_TPS40422) += tps40422.o
> > obj-$(CONFIG_SENSORS_TPS53679) += tps53679.o
> > +obj-$(CONFIG_SENSORS_TPS546D24) += tps546d24.o
> > obj-$(CONFIG_SENSORS_UCD9000) += ucd9000.o
> > obj-$(CONFIG_SENSORS_UCD9200) += ucd9200.o
> > obj-$(CONFIG_SENSORS_XDPE122) += xdpe12284.o
> > diff --git a/drivers/hwmon/pmbus/tps546d24.c b/drivers/hwmon/pmbus/tps546d24.c
> > new file mode 100644
> > index 0000000..f6f79d3
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus/tps546d24.c
> > @@ -0,0 +1,73 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Hardware monitoring driver for TEXAS TPS546D24 buck converter
> > + */
> > +
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/pmbus.h>
> > +#include "pmbus.h"
> > +
> > +static int tps546d24_read_byte_data(struct i2c_client *client, int page, int reg)
> > +{
> > + int ret;
> > +
> > + switch (reg) {
> > + case PMBUS_VOUT_MODE:
> > + ret = 0x17;
> > + break;
> > + default:
> > + ret = -ENODATA;
> > + break;
> > + }
> > + return ret;
> > +}
> > +
> > +static struct pmbus_driver_info tps546d24_info = {
> > + .pages = 1,
> > + .format[PSC_VOLTAGE_IN] = linear,
> > + .format[PSC_VOLTAGE_OUT] = linear,
> > + .format[PSC_TEMPERATURE] = linear,
> > + .format[PSC_CURRENT_OUT] = linear,
> > + .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN |
> > + PMBUS_HAVE_IOUT | PMBUS_HAVE_VOUT |
> > + PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_VOUT |
> > + PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
> > + .read_byte_data = tps546d24_read_byte_data,
>
> The chip supports multiple phases, and per-phase telemetry.
> Have you considered supporting it ?
>
> > +};
> > +
> > +static int tps546d24_probe(struct i2c_client *client)
> > +{
> > + return pmbus_do_probe(client, &tps546d24_info);
> > +}
> > +
> > +static const struct i2c_device_id tps546d24_id[] = {
> > + {"tps546d24", 0},
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(i2c, tps546d24_id);
> > +
> > +static const struct of_device_id __maybe_unused tps546d24_of_match[] = {
> > + {.compatible = "tps546d24"},
>
> This needs a vendor prefix.
>
> > + {}
> > +};
> > +
> > +/* This is the driver that will be inserted */
> > +static struct i2c_driver tps546d24_driver = {
> > + .driver = {
> > + .name = "tps546d24",
> > + .of_match_table = of_match_ptr(tps546d24_of_match),
> > + },
> > + .probe_new = tps546d24_probe,
> > + .id_table = tps546d24_id,
> > +};
> > +
> > +module_i2c_driver(tps546d24_driver);
> > +
> > +MODULE_AUTHOR("Duke Du <dukedu83@...il.com>");
> > +MODULE_DESCRIPTION("PMBus driver for TI tps546d24");
> > +MODULE_LICENSE("GPL");
> > +MODULE_IMPORT_NS(PMBUS);
> > --
> > 2.7.4
> >
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