linux-kernel - Re: [PATCH v6 01/10] i3c: Add core I3C infrastructure

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Date:   Thu, 6 Sep 2018 12:43:34 +0000
From:   Przemyslaw Gaj <pgaj@...ence.com>
To:     vitor <Vitor.Soares@...opsys.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>
CC:     "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Sekhar Nori <nsekhar@...com>, Wolfram Sang <wsa@...-dreams.de>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Przemyslaw Sroka <psroka@...ence.com>,
        Arkadiusz Golec <agolec@...ence.com>,
        Alan Douglas <adouglas@...ence.com>,
        Bartosz Folta <bfolta@...ence.com>,
        Damian Kos <dkos@...ence.com>,
        Alicja Jurasik-Urbaniak <alicja@...ence.com>,
        Cyprian Wronka <cwronka@...ence.com>,
        Suresh Punnoose <sureshp@...ence.com>,
        Rafal Ciepiela <rafalc@...ence.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Nishanth Menon <nm@...com>, Rob Herring <robh+dt@...nel.org>,
        Pawel Moll <pawel.moll@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Kumar Gala <galak@...eaurora.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Xiang Lin <Xiang.Lin@...aptics.com>,
        Peter Rosin <peda@...ntia.se>
Subject: Re: [PATCH v6 01/10] i3c: Add core I3C infrastructure

Hi Boris, Vitor,

This repository does not contain full kernel sources, but it should be enough to discuss mastership request feature. 
https://github.com/przemekgaj/i3c-linux/commit/d54fe68a9d3e573c0c454a2c6f1afafc20142ec5

Please keep in mind that this is initial version, but mastership works correctly. I added one property to DT to reflect relationship between masters.
It is possible to request mastership on demand (using sysfs. Useful in case when Linux machine is equipped only with secondary master controller) or automatically change operation mode when device driver wants to read/write something from/to device.

I'm sure I will have to rework something because this was implemented on sources from PATCH v4. I saw that Boris released v7 yesterday :)

Thanks,
Przemek

On 9/3/18, 11:33 AM, "vitor" <Vitor.Soares@...opsys.com> wrote:

    EXTERNAL MAIL
    
    
    Hi Przemek,
    
    
    On 30-08-2018 20:00, Przemyslaw Gaj wrote:
    >      So, per my understanding since the Main master support the hand-off of
    >      the bus you accept all incoming MR, right? Or do you check all devices BCR?
    >
    > I'm not sure what do you mean here. Mastership request(MR) is from secondary master
    > to current master. Current master can NACK this request if for example it comes from
    > wrong device. If it's ok, current master sends GETACCMST command and secondary master
    > may ACK or NACK this command. It it's acked, secondary master becomes current master.
    >      
    >      Best regards,
    >      Vitor Soares
    >
    > Please let me know if something is unclear.
    >
    > Regards,
    > Przemek
    >      
    
    Sorry, it s not clear yet.
    
    For instances there is a bus with several secondary master. If each of 
    them request the bus mastership (one at a time), will you accept all by 
    default? Because you can only accept only some of them.
    
    Regards,
    Vitor Soares