Hi Geert,
Thanks for the feedback.
> Subject: Re: [PATCH] i2c: Add i2c_get_match_data()
>
> Hi Biju,
>
> On Mon, May 22, 2023 at 2:38 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> wrote:
> > > -----Original Message-----
> > > From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > > Sent: Monday, May 22, 2023 12:29 PM
> > > To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > Cc: Wolfram Sang <wsa@xxxxxxxxxx>; linux-i2c@xxxxxxxxxxxxxxx;
> > > Alessandro Zummo <a.zummo@xxxxxxxxxxxx>; Alexandre Belloni
> > > <alexandre.belloni@xxxxxxxxxxx>; Prabhakar Mahadev Lad
> > > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>; linux-renesas-
> > > soc@xxxxxxxxxxxxxxx
> > > Subject: Re: [PATCH] i2c: Add i2c_get_match_data()
> > >
> > > Hi Biju,
> > >
> > > On Mon, May 22, 2023 at 12:42 PM Biju Das
> > > <biju.das.jz@xxxxxxxxxxxxxx>
> > > wrote:
> > > > Add i2c_get_match_data() similar to of_device_get_match_data(), so
> > > > that we can optimize the driver code that uses both I2C and
> > > > DT-based matching.
> > > >
> > > > Suggested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > >
> > > Thanks for your patch!
> > >
> > > > --- a/drivers/i2c/i2c-core-base.c
> > > > +++ b/drivers/i2c/i2c-core-base.c
> > > > @@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32
> > > > bus_freq_hz) } EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
> > > >
> > > > -const struct i2c_device_id *i2c_match_id(const struct
> > > > i2c_device_id
> > > *id,
> > > > - const struct
> > > i2c_client *client)
> > > > +static const struct i2c_device_id *i2c_match_device_id(const
> > > > +struct
> > > i2c_device_id *id,
> > > > + const
> > > > +struct i2c_client *client)
> > > > {
> > > > if (!(id && client))
> > > > return NULL;
> > > > @@ -110,10 +110,30 @@ const struct i2c_device_id
> > > > *i2c_match_id(const
> > > struct i2c_device_id *id,
> > > > return id;
> > > > id++;
> > > > }
> > > > +
> > > > return NULL;
> > > > }
> > > > +
> > > > +const struct i2c_device_id *i2c_match_id(const struct
> > > > +i2c_device_id
> > > *id,
> > > > + const struct i2c_client
> > > > +*client) {
> > > > + return i2c_match_device_id(id, client); }
> > > > EXPORT_SYMBOL_GPL(i2c_match_id);
> > >
> > > Is there any reason why you're adding a new intermediate?
> >
> > The same code is shared between below function.
> > As discussed below, it is not required.
> >
> > >
> > > >
> > > > +const void *i2c_get_match_data(const struct i2c_device_id *id,
> > > > + const struct i2c_client *client)
> > >
> > > I think this should take the id table from the i2c_driver, as
> > > pointed to by client->dev.driver, instead of from an explicitly
> passed parameter.
> >
> > You mean const void *i2c_get_match_data(const struct i2c_client
> *client)??
> >
> > struct i2c_driver *driver = client->dev.driver;
>
> also needs to_i2c_driver()
OK.
>
> >
> > And then call
> >
> > match = i2c_match_id(driver->id_table, client)??
>
> Exactly.
>
> > > > +{
> > > > + const struct i2c_device_id *match;
> > > > +
> > > > + match = i2c_match_device_id(id, client);
> > > > + if (!match)
> > > > + return NULL;
> > > > +
> > > > + return (const void *)match->driver_data;
> > >
> > > One can discuss about the returned type: personally, I won't mind
> > > "const void *" for consistency with other subsystems (e.g. DT), but
> > > as i2c_device_id.driver_data has type "kernel_ulong_t", other people
> > > might prefer the latter.
> >
> > The advantage of void*, is upper layer don't need casting.
>
> Depending on what the driver wants...
> Some drivers want integers, other want pointers...
For integer and enums, already most of the drivers are using like this
chip_id = i2c_match_id(max20730_id, client)->driver_data;
>
> > eg: with kernel_ulong_t as return parameter:
> >
> > isl1208->config = (struct isl1208_config *)i2c_get_match_data;
>
> I know ;-)
> For the isl1208 case, "void *" simplifies the driver...
But with return type as "void *" the below drivers can make use of it,
as these drivers never checks return type for "i2c_match_id".
drivers/iio/potentiometer/mcp4018.c: data->cfg = &mcp4018_cfg[i2c_match_id(mcp4018_id, client)->driver_data];
drivers/iio/accel/adxl313_i2c.c: chip_data = (const struct adxl313_chip_info *)i2c_match_id(adxl313_i2c_id, client)->driver_data;
drivers/iio/accel/adxl355_i2c.c: chip_data = (void *)i2c_match_id(adxl355, client)->driver_data;
drivers/rtc/rtc-pcf85063.c- config = &pcf85063_cfg[type];
drivers/i2c/muxes/i2c-mux-ltc4306.c: chip = &chips[i2c_match_id(ltc4306_id, client)->driver_data];
drivers/hwmon/sht3x.c- attribute_groups = sts3x_groups;
drivers/hwmon/pmbus/pmbus.c: device_info = (struct pmbus_device_info *)i2c_match_id(pmbus_id, client)->driver_data;
I will send next version based on return type as void*,
Based on wider feedback if needed will change return type.
Hope it is ok??
Cheers,
Biju
