Messages in this thread | | | Subject | Re: [prefix=PATCH] drivers: pmbus: core: Prevent calling pmbus_set_page with negative page | From | Eddie James <> | Date | Wed, 25 Oct 2017 16:23:01 -0500 |
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On 10/25/2017 04:12 PM, Guenter Roeck wrote: > On Wed, Oct 25, 2017 at 02:52:53PM -0500, Eddie James wrote: >> From: "Edward A. James" <eajames@us.ibm.com> >> >> For devices with word data registers, the pmbus core may call read/write >> word data functions with a page value of -1, in order to perform the >> operation without setting the page. However, the read/write word data >> functions accept only unsigned 8-bit page numbers, resulting in setting >> a page of 0xFF in this situation. This may result in errors or undefined >> behavior of some devices (specifically the ir35221, which allows the >> page to be set to 0xFF, but some subsequent operations to read registers >> may fail). >> > Good catch. > > Subject came off a bit odd. > > [prefix=PATCH] drivers: pmbus: core: Prevent ... > > Please use "[PATCH] hwmon: (pmbus/core) Prevent ..."
Yea I hit = instead of - in "--subject-prefix"...
> > This me wonder if we should move the check into pmbus_set_page() > instead. > > int pmbus_set_page(struct i2c_client *client, int page) > { > ... > if (page >= 0 && page != data->currpage) { > ... > } > > What do you think ?
Yea that works well too, and reduces the code size. Though I suppose it makes the interface slightly less intuitive, as someone might think they can pass a value larger than u8. At least for the read/write functions, a negative value has a meaning - "don't change the page."
Up to you, either way. I'm happy to change it.
Thanks, Eddie
> > Thanks, > Guenter > >> Signed-off-by: Edward A. James <eajames@us.ibm.com> >> --- >> drivers/hwmon/pmbus/pmbus.h | 4 ++-- >> drivers/hwmon/pmbus/pmbus_core.c | 29 ++++++++++++++++++----------- >> 2 files changed, 20 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h >> index 4efa2bd..4a16da6 100644 >> --- a/drivers/hwmon/pmbus/pmbus.h >> +++ b/drivers/hwmon/pmbus/pmbus.h >> @@ -405,8 +405,8 @@ struct pmbus_driver_info { >> >> void pmbus_clear_cache(struct i2c_client *client); >> int pmbus_set_page(struct i2c_client *client, u8 page); >> -int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg); >> -int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word); >> +int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg); >> +int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, u16 word); >> int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg); >> int pmbus_write_byte(struct i2c_client *client, int page, u8 value); >> int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, >> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c >> index 302f0ae..6d6e030 100644 >> --- a/drivers/hwmon/pmbus/pmbus_core.c >> +++ b/drivers/hwmon/pmbus/pmbus_core.c >> @@ -186,13 +186,16 @@ static int _pmbus_write_byte(struct i2c_client *client, int page, u8 value) >> return pmbus_write_byte(client, page, value); >> } >> >> -int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word) >> +int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, >> + u16 word) >> { >> int rv; >> >> - rv = pmbus_set_page(client, page); >> - if (rv < 0) >> - return rv; >> + if (page >= 0) { >> + rv = pmbus_set_page(client, page); >> + if (rv < 0) >> + return rv; >> + } >> >> return i2c_smbus_write_word_data(client, reg, word); >> } >> @@ -219,13 +222,15 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg, >> return pmbus_write_word_data(client, page, reg, word); >> } >> >> -int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg) >> +int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg) >> { >> int rv; >> >> - rv = pmbus_set_page(client, page); >> - if (rv < 0) >> - return rv; >> + if (page >= 0) { >> + rv = pmbus_set_page(client, page); >> + if (rv < 0) >> + return rv; >> + } >> >> return i2c_smbus_read_word_data(client, reg); >> } >> @@ -269,9 +274,11 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value) >> { >> int rv; >> >> - rv = pmbus_set_page(client, page); >> - if (rv < 0) >> - return rv; >> + if (page >= 0) { >> + rv = pmbus_set_page(client, page); >> + if (rv < 0) >> + return rv; >> + } >> >> return i2c_smbus_write_byte_data(client, reg, value); >> } >> -- >> 1.8.3.1 >>
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