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From:   Parshuram Raju Thombare <pthombar@cadence.com>
To:     Alexandre Belloni <alexandre.belloni@bootlin.com>
CC:     "slongerbeam@gmail.com" <slongerbeam@gmail.com>,
        "vitor.soares@synopsys.com" <vitor.soares@synopsys.com>,
        "linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>,
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        Milind Parab <mparab@cadence.com>,
        "praneeth@ti.com" <praneeth@ti.com>
Subject: RE: [PATCH v10 7/7] i3c: master: mastership handover, defslvs
 processing in cdns controller driver
Thread-Topic: [PATCH v10 7/7] i3c: master: mastership handover, defslvs
 processing in cdns controller driver
Thread-Index: AQHWxuDs+/K7hYXed0i4eOriGwBa1asL83QAgA1A+kA=
Date:   Thu, 17 Jun 2021 10:28:11 +0000
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>I don't really get why being a secondary master would be hardcoded in
>the IP. What happens if multiple cadence masters have
>CONF_STATUS0_SEC_MASTER unset and are on the same bus?
>
>Also, it feels weird to let that kind of decision to the master driver.
>I would really think the use case would be that each master on the bus
>is running on a different system. I don't really see the point of having
>the primary and the secondary on the bus on the same system.
>
>Then, we definitively want to let the decision of which master is the
>current master at boot to the HW designer which will depend on what is
>present on the board

Since I3C bus can have only one master at a time, it is necessary to be dec=
ide
Which master device is capable of doing initialization which includes assig=
ning
dynamic addresses to all devices and sending DEFLVS, and can be considered
as main master to call i3c_primary_master_register. This decision about whi=
ch=20
master is capable of acting as main master seems controller specific.
=20
Cadence's Master controller IP can act as main master or secondary master.
There are differences in their functionalities. However, if other controlle=
rs
support both modes equally, their driver can chose any master device to act
as main master, or use any other controller specific methods to decide main
master.=20

>> +	if (secondary)
>> +		INIT_WORK(&master->defslvs_work, cdns_i3c_sec_master_defslvs);
>> +
>Don't you need any master to be able to handle defslvs to be able to
>request mastership?

This is for secondary master only. DEFSLVS is sent by current master, after
DAA, to ensure that all masters have information about all devices on the b=
us.