linux-kernel - Re: [PATCHv10 2/4] mailbox: Introduce framework for mailbox

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Message-ID: <54206B7C.60501@arm.com>
Date:	Mon, 22 Sep 2014 19:33:32 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	Jassi Brar <jaswinder.singh@...aro.org>
CC:	Sudeep Holla <sudeep.holla@....com>,
	Devicetree List <devicetree@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	"ks.giri@...sung.com" <ks.giri@...sung.com>,
	Arnd Bergmann <arnd@...db.de>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	Mark Rutland <Mark.Rutland@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <Pawel.Moll@....com>,
	Courtney Cavin <courtney.cavin@...ymobile.com>,
	Matt Porter <mporter@...aro.org>,
	Craig McGeachie <slapdau@...oo.com.au>,
	LeyFoon Tan <lftan.linux@...il.com>,
	Loic Pallardy <loic.pallardy@...com>,
	"Anna, Suman" <s-anna@...com>, Bjorn Andersson <bjorn@...o.se>,
	Patch Tracking <patches@...aro.org>,
	"mollie.wu@...aro.org" <mollie.wu@...aro.org>,
	Tetsuya Takinishi <t.takinishi@...fujitsu.com>,
	"broonie@...aro.org" <broonie@...aro.org>,
	Kevin Hilman <khilman@...aro.org>,
	"lee.jones@...aro.org" <lee.jones@...aro.org>,
	"andy.green@...aro.org" <andy.green@...aro.org>
Subject: Re: [PATCHv10 2/4] mailbox: Introduce framework for mailbox



On 22/09/14 19:15, Sudeep Holla wrote:
>
>
> On 22/09/14 19:01, Ashwin Chaugule wrote:
>> Hi Jassi,
>>
>> On 1 August 2014 08:31, Jassi Brar <jaswinder.singh@...aro.org> wrote:
>>> Introduce common framework for client/protocol drivers and
>>> controller drivers of Inter-Processor-Communication (IPC).
>>>
>>> Client driver developers should have a look at
>>>    include/linux/mailbox_client.h to understand the part of
>>> the API exposed to client drivers.
>>> Similarly controller driver developers should have a look
>>> at include/linux/mailbox_controller.h
>>>
>>> Signed-off-by: Jassi Brar <jaswinder.singh@...aro.org>
>>> ---
>>>    MAINTAINERS                        |   8 +
>>>    drivers/mailbox/Makefile           |   4 +
>>>    drivers/mailbox/mailbox.c          | 466 +++++++++++++++++++++++++++++++++++++
>>>    include/linux/mailbox_client.h     |  46 ++++
>>>    include/linux/mailbox_controller.h | 135 +++++++++++
>>>    5 files changed, 659 insertions(+)
>>>    create mode 100644 drivers/mailbox/mailbox.c
>>>    create mode 100644 include/linux/mailbox_client.h
>>>    create mode 100644 include/linux/mailbox_controller.h
>>>
>>
>> [..]
>>
>>> +
>>> +static void poll_txdone(unsigned long data)
>>> +{
>>> +       struct mbox_controller *mbox = (struct mbox_controller *)data;
>>> +       bool txdone, resched = false;
>>> +       int i;
>>> +
>>> +       for (i = 0; i < mbox->num_chans; i++) {
>>> +               struct mbox_chan *chan = &mbox->chans[i];
>>> +
>>> +               if (chan->active_req && chan->cl) {
>>> +                       resched = true;
>>> +                       txdone = chan->mbox->ops->last_tx_done(chan);
>>> +                       if (txdone)
>>> +                               tx_tick(chan, 0);
>>> +               }
>>> +       }
>>> +
>>> +       if (resched)
>>> +               mod_timer(&mbox->poll, jiffies +
>>> +                               msecs_to_jiffies(mbox->period));
>>
>> While preparing a different patch which uses the Mbox framework, I
>> noticed that mbox->period might not be initialized anywhere. Also, how
>> is mbox->txpoll_period to be used? It appears from the description of
>> txpoll_period in mbox_controller.h that you'd want to use that value
>> in the mod_timer above, or equate the two somewhere in the controller
>> registration or eliminate one of the two. FWIW I also looked at your
>> code in [1].
>>
>
> IIUC the controller needs to set the txpoll_period if it sets
> txdone_poll, may be a sanity check for !0 would be good.
>

Ah, sorry I confused mbox->period to txpoll_period.
You are right mbox->period is not set, the header claims it to be
private, and hence I assume it needs to be handled only in core mailbox
library. Not sure if we need both mbox->period and txpoll_period though.

Regards,
Sudeep

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