Linux-i3c Archive on lore.kernel.org
 help / color / Atom feed
From: Przemyslaw Gaj <pgaj@cadence.com>
To: Vitor Soares <Vitor.Soares@synopsys.com>
Cc: "linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	"bbrezillon@kernel.org" <bbrezillon@kernel.org>
Subject: Re: I3C Mastership RFC
Date: Mon, 25 Nov 2019 12:55:16 +0100
Message-ID: <20191125115502.GA5777@global.cadence.com> (raw)
In-Reply-To: <CH2PR12MB42168C76A833F1401A597E65AE4A0@CH2PR12MB4216.namprd12.prod.outlook.com>

The 11/25/2019 11:42, Vitor Soares wrote:
> 
> Hi Boris,
> 
> From: Boris Brezillon <boris.brezillon@collabora.com>
> Date: Mon, Nov 25, 2019 at 11:34:52
> 
> > On Mon, 25 Nov 2019 11:19:44 +0000
> > Vitor Soares <Vitor.Soares@synopsys.com> wrote:
> > 
> > > > > > > 
> > > > > > > I based in all version and tried to pass everything to master.c file.  
> > > > > > 
> > > > > > I'm not sure what that means, but okay.
> > > > > >   
> > > > > > > Right now my challenge it to trigger mastership request when a device 
> > > > > > > driver want to access to the bus but I believe we can discuss that after.  
> > > > > > 
> > > > > > That's kind of a basic feature when talking about mastership handover,
> > > > > > but sure, we can discuss it after your RFC has been posted.  
> > > > > 
> > > > > I need to test if the time that device.c request the mastership and the 
> > > > > controller has effectively the ownership of the bus is short enough to 
> > > > > call i3c_dev_do_priv_xfers_locked(dev->desc, xfers, nxfers) before of all 
> > > > > housekeeping of bus takeover.
> > > > >   
> > > > > > 
> > > > > > Note that I'm not super happy to have to go back to square 1 and throw
> > > > > > away all of the work done by Przemek, especially since Przemek was the
> > > > > > first one to post a patchset and he never really said he didn't
> > > > > > want or didn't have time to continue working on this task (not even
> > > > > > mentioning the time I spent reviewing those patches...).
> > > > > > 
> > > > > > If Przemek is fine with this situation I'm okay making an exception,
> > > > > > but be aware that it's not how we usually do: the person that posts a
> > > > > > patchset first leads the thing (of course, it's even better if there's
> > > > > > some kind of coordination before the patch is posted).  
> > > > > 
> > > > > Honestly it looks like I'm competing on this which is not the case.
> > > > > I just pointed out my concerns about this adoption because I see several 
> > > > > issues on it. The point is, at the end you can pick some parts of my sec 
> > > > > master code and integrate in your solution.
> > > > >   
> > > > 
> > > > Can you point me to the version of the patch your changes are based on?
> > > > And also, can you tell me what issues you faced? I would like to check
> > > > if they are already adressed in my code.  
> > > 
> > > I used v3 and v4. From v5, I found useful the switch case (request, 
> > > deliver, handoff, takeover) in hc side.
> > > 
> > > I didn't hardly test how device.c request mastership but I suspect it 
> > > won't work properly. When you do i3c_dev_do_priv_xfers_locked() you might 
> > > not be the master yet.
> > 
> > I'm pretty sure we solved that already (that's what
> > i3c_master_acquire_bus_ownership() calls are supposed to take care of).
> > Can you be a bit more specific? What makes you think the master might
> > not be in control of the bus when i3c_dev_do_priv_xfers_locked() is
> > called?
> 
> You are assuming that after i3c_master_acquire_bus_ownership() return, 
> secondary master already owns the bus. Main master can ack the MR request 
> and not send the CETACCMST immediately.
>

In Cadence HC driver, I'm waiting for GETACCMST longer, polling the
status and after I exit from ->request_mastership(), I'm the bus owner.
If not, error exit code is returned and we can't make the transfers.
Are you able to implement the same behavior?
 
> I was thinking to delay i3c_dev_do_priv_xfers_locked() with a work delay 
> or so. Do you have any idea?
> 
> > 
> > > 
> > > >   
> > > > > As I said previous for I3C spec 1.1 secondary master received a big 
> > > > > improvement due the misunderstanding published in 1.0 spec. I don't know 
> > > > > any other protocol that implement such kind of feature and for this is 
> > > > > from far the most complex feature to implement in SO based systems from 
> > > > > i3c spec.
> > > > >   
> > > > > > 
> > > > > > BTW, you mentioned working on a lot of different topics, but most of
> > > > > > them were left unfinished (userspace i3cdev interface, I3C slave
> > > > > > framework/API, ...).  
> > > > > 
> > > > > The i3cdev does what we discuss during the proposal of i3c subsystem and 
> > > > > only expose i3c device without device driver yet I'm not happy with 
> > > > > transfer struct.
> > > > > For the tools I have for hdr and sdr transfers, for now I didn't feel the 
> > > > > need of a tool for ccc (but for testing purposes it would help a lot).
> > > > >   
> > > > > > Any plans to post RFCs on those aspects anytime
> > > > > > soon? I mean, there's plenty of topics to work on, and I'd really prefer
> > > > > > that each developer work on a different topic instead of duplicating the
> > > > > > effort...
> > > > > > 
> > > > > > Regards,
> > > > > > 
> > > > > > Boris  
> > > > > 
> > > > > Best regards,
> > > > > Vitor Soares
> > > > > 
> > > > >   
> > > > 
> > > > -- 
> > > > -- 
> > > > Regards,
> > > > Przemyslaw Gaj  
> > > 
> > > Again sorry for the delay. I will try to send this soon.
> > 
> > Can you please share what you have now (even if it's not finished) so
> > Przemek can start looking at it?
> 
> I will try today.
> 
> Best regads,
> Vitor Soares
> 

-- 
-- 
Przemyslaw Gaj

_______________________________________________
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  9:33 Przemyslaw Gaj
2019-11-10 10:30 ` Boris Brezillon
2019-11-11 12:30   ` Vitor Soares
2019-11-12  7:41     ` Boris Brezillon
2019-11-14  6:10       ` Przemyslaw Gaj
2019-11-14 11:56         ` Vitor Soares
2019-11-14 12:32           ` Boris Brezillon
2019-11-14 12:59             ` Przemyslaw Gaj
2019-11-14 14:17             ` Vitor Soares
2019-11-14 14:50               ` Boris Brezillon
2019-11-14 20:15                 ` Przemyslaw Gaj
2019-11-25  8:02               ` Przemyslaw Gaj
2019-11-25 11:19                 ` Vitor Soares
2019-11-25 11:34                   ` Boris Brezillon
2019-11-25 11:42                     ` Vitor Soares
2019-11-25 11:55                       ` Przemyslaw Gaj [this message]
2019-11-25 12:03                         ` Vitor Soares
2019-11-25 12:22                           ` Boris Brezillon
2019-11-25 13:00                             ` Vitor Soares
2019-11-25 13:09                               ` Boris Brezillon
2019-11-25 14:27                                 ` Vitor Soares
2019-11-25 14:50                                   ` Boris Brezillon
2019-11-25 14:59                                   ` Przemyslaw Gaj
2019-11-25 15:22                                     ` Vitor Soares
2019-11-25 12:25                           ` Przemyslaw Gaj
2019-11-25 12:56                             ` Vitor Soares
2019-11-25 11:50                     ` Przemyslaw Gaj

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191125115502.GA5777@global.cadence.com \
    --to=pgaj@cadence.com \
    --cc=Vitor.Soares@synopsys.com \
    --cc=bbrezillon@kernel.org \
    --cc=boris.brezillon@collabora.com \
    --cc=linux-i3c@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-i3c Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-i3c/0 linux-i3c/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-i3c linux-i3c/ https://lore.kernel.org/linux-i3c \
		linux-i3c@lists.infradead.org
	public-inbox-index linux-i3c

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-i3c


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git