On Saturday 22 June 2024 16:14:11 Hans de Goede wrote: > Hi Pali, > > On 6/22/24 4:08 PM, Pali Rohár wrote: > > On Saturday 22 June 2024 15:56:03 Hans de Goede wrote: > >> Hi, > >> > >> On 6/22/24 2:46 PM, Pali Rohár wrote: > >>> On Friday 21 June 2024 14:24:57 Hans de Goede wrote: > >>>> On chipsets with a second 'Integrated Device Function' SMBus controller use > >>>> a different adapter-name for the second IDF adapter. > >>>> > >>>> This allows platform glue code which is looking for the primary i801 > >>>> adapter to manually instantiate i2c_clients on to differentiate > >>>> between the 2. > >>>> > >>>> This allows such code to find the primary i801 adapter by name, without > >>>> needing to duplicate the PCI-ids to feature-flags mapping from i2c-i801.c. > >>>> > >>>> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >>>> --- > >>>> drivers/i2c/busses/i2c-i801.c | 9 +++++++-- > >>>> 1 file changed, 7 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c > >>>> index d2d2a6dbe29f..5ac5bbd60d45 100644 > >>>> --- a/drivers/i2c/busses/i2c-i801.c > >>>> +++ b/drivers/i2c/busses/i2c-i801.c > >>>> @@ -1760,8 +1760,13 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id) > >>>> > >>>> i801_add_tco(priv); > >>>> > >>>> - snprintf(priv->adapter.name, sizeof(priv->adapter.name), > >>>> - "SMBus I801 adapter at %04lx", priv->smba); > >>>> + if (priv->features & FEATURE_IDF) > >>>> + snprintf(priv->adapter.name, sizeof(priv->adapter.name), > >>>> + "SMBus I801 IDF adapter at %04lx", priv->smba); > >>>> + else > >>>> + snprintf(priv->adapter.name, sizeof(priv->adapter.name), > >>>> + "SMBus I801 adapter at %04lx", priv->smba); > >>>> + > >>> > >>> User visible name is identifier for user / human. > >>> > >>> If somebody is going to read this code in next 10 years then can ask > >>> question why to have different name for IDF FEATURE and not also for > >>> other features? And can come to conclusion to unify all names to be > >>> same (why not? it is user identifier). > >> > >> That is a good point, I'll add a comment about this for the next > >> version. > >> > >>> Depending on user names between different kernel subsystem is fragile, > >>> specially for future as rename can happen. > >> > >> Relying no devices names to find devices is standard practice. E.g. > >> this is how 99% of the platform drivers bind to platform devices > >> by the driver and the device having the same name. > > > > But here it is adapter name which is more likely description, not the > > device name which is used for binding. > > It is still matching on a name. > > >>> If you are depending on FEATURE_IDF flag then check for the flag > >>> directly, and not hiding the flag by serializing it into the user > >>> visible name (char[] variable) and then de-serializing it in different > >>> kernel subsystem. If the flag is not exported yet then export it via > >>> some function or other API. > >> > >> Exporting this through some new function is non trivial and adds > >> extra dependencies between modules, causing issues when one is builtin > >> and the other is build as a module. > > > > Access to "struct i801_priv *" is not possible? For example via > > dev_get_drvdata() on "struct device *" which you have in > > smo8800_find_i801()? > > > > Because if it is possible then you can create an inline function in some > > shared header file which access this flag. Not perfect (as accessing > > private data is not the best thing) but can avoid dependences between > > modules. > > Prodding inside another drivers private driver struct is a big nono > and much much more fragile then the name checking. I know, that is why I wrote to access this structure and flags in separate function which can be an inline in e.g. i2c-i801.h header file. > Regards, > > Hans > >
