linux-kernel - Re: [PATCH v3 3/8] mailbox: Add transmit done by blocking option

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Date:   Sat, 4 Aug 2018 13:45:49 +0300
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Jassi Brar <jassisinghbrar@...il.com>,
        Mikko Perttunen <mperttunen@...dia.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Devicetree List <devicetree@...r.kernel.org>,
        linux-serial@...r.kernel.org, linux-tegra@...r.kernel.org,
        ", linux-arm-kernel"@lists.infradead.org,
        linux-mediatek@...ts.infradead.org,
        srv_heupstream <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/8] mailbox: Add transmit done by blocking option

On 08/03/2018 03:54 PM, Jassi Brar wrote:
> On Mon, Jul 2, 2018 at 5:10 PM, Mikko Perttunen <mperttunen@...dia.com> wrote:
>> Add a new TXDONE option, TXDONE_BY_BLOCK. With this option, the
>> send_data function of the mailbox driver is expected to block until
>> the message has been sent. The new option is used with the Tegra
>> Combined UART driver to minimize unnecessary overhead when transmitting
>> data.
>>
> 1) TXDONE_BY_BLOCK flag :-
>          Have you tried setting the flag mbox_chan->mbox_client->tx_block ?

No - I suppose I should have done that. I'm a bit concerned about 
overhead as send_data may be called thousands of times per second, so I 
tried to make it as close as possible to the downstream driver that just 
pokes the mailbox register directly.

> 
> 2) Implementing TEGRA_HSP_MBOX_TYPE_SM :-
>         In mailbox framework, a controller is a collection of identical
> channels. That is, instances of the same class.
>         So ideally, in probe you should populate a controller for each
> type of channel, i.e, DB, SM, SS and AS.

Hmm, yes, I guess this would be possible if I change the mailbox core to 
allow registering multiple controllers per device.

Thanks!
Mikko

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