Re: [PATCH v4 1/6] i3c: add addr and lvr to i2c_dev_desc structure

Przemyslaw Gaj
2019-04-02T11:23:06Z

Hi,

The 04/02/2019 12:10, vitor wrote:
>
> Hi,
>
>
> On 01/04/19 20:24, Boris Brezillon wrote:
> > On Mon, 1 Apr 2019 19:48:45 +0100
> > vitor <vitor.soares@synopsys.com> wrote:
> >
> >> Hi,
> >>
> >> On 01/04/19 19:31, Boris Brezillon wrote:
> >>> On Mon, 1 Apr 2019 19:17:03 +0100
> >>> vitor <vitor.soares@synopsys.com> wrote:
> >>>
> >>>> Hi,
> >>>>
> >>>> On 30/03/19 14:36, Boris Brezillon wrote:
> >>>>> On Sun, 10 Mar 2019 13:58:38 +0000
> >>>>> Przemyslaw Gaj <pgaj@cadence.com> wrote:
> >>>>>
> >>>>>> I need to store address and lvr value for I2C devices without static definition
> >>>>>> in DT. This allows secondary master to transmit DEFSLVS command properly.
> >>>>>>
> >>>>>> Signed-off-by: Przemyslaw Gaj <pgaj@cadence.com>
> >>>>>> ---
> >>>>>> include/linux/i3c/master.h | 5 +++++
> >>>>>> 1 file changed, 5 insertions(+)
> >>>>>>
> >>>>>> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> >>>>>> index eca8337..3c27d9f 100644
> >>>>>> --- a/include/linux/i3c/master.h
> >>>>>> +++ b/include/linux/i3c/master.h
> >>>>>> @@ -71,6 +71,9 @@ struct i2c_dev_boardinfo {
> >>>>>> * @common: common part of the I2C device descriptor
> >>>>>> * @boardinfo: pointer to the boardinfo attached to this I2C device
> >>>>>> * @dev: I2C device object registered to the I2C framework
> >>>>>> + * @addr: I2C device address
> >>>>>> + * @lvr: LVR (Legacy Virtual Register) needed by the I3C core to know about
> >>>>>> + * the I2C device limitations
> >>>>>> *
> >>>>>> * Each I2C device connected on the bus will have an i2c_dev_desc.
> >>>>>> * This object is created by the core and later attached to the controller
> >>>>>> @@ -84,6 +87,8 @@ struct i2c_dev_desc {
> >>>>>> struct i3c_i2c_dev_desc common;
> >>>>>> const struct i2c_dev_boardinfo *boardinfo;
> >>>>>> struct i2c_client *dev;
> >>>>>> + u16 addr;
> >>>>>> + u8 lvr;
> >>>>> You also need to remove lvr from i2c_dev_boardinfo and adjust the code
> >>>>> to use i2c_dev_desc->addr and i2c_dev_desc->lvr in this patch, not in
> >>>>> patch 3.
> >>>>>
> >>>> Why can't we keep the lvr and addr in i2c_dev_boardinfo and need this information on i2c_dev_desc?
> >>> Because i2c_dev_boardinfo is extracted from the DT and the secondary
> >>> slaves does not necessarily have this description. The idea is to keep
> >>> reserving the address slot for the I2C device even if we don't expose
> >>> it to the upper layers.
> >> So you are using i2c_dev_boardinfo just for DT devices?
> > All devices that are described in some way, can be through DT, ACPI or
> > board-file desc (only DT is supported right now, but we can easily add
> > support for other formats).
>
> We can drop i2c_dev_boardinfo.
>

Why you think we can drop it? We are still using it for DT devices.

> >
> >> Because at end we need to register the new i2c devs.
> > No, only those that have a valid description, because there's nothing
> > you can expose if you only have the address and LVR values. You at
> > least need to know which driver this dev should be attached to
> > (compatible string in your DT) and most drivers also need extra
> > information (basically all the DT props that are described a the DT
> > binding).
>
> In any case the HC need to know the bus mode, how is this done?

LVR is passed through DEFSLVS command.

--
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Przemyslaw Gaj