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

From: Mikko Perttunen <cyndis@kapsi.fi>
To: Jassi Brar <jassisinghbrar@gmail.com>,
	Mikko Perttunen <mperttunen@nvidia.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jon Hunter <jonathanh@nvidia.com>,
	Devicetree List <devicetree@vger.kernel.org>,
	linux-serial@vger.kernel.org, linux-tegra@vger.kernel.org, ",
	linux-arm-kernel"@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	srv_heupstream <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 3/8] mailbox: Add transmit done by blocking option
Date: Sat, 4 Aug 2018 13:45:49 +0300	[thread overview]
Message-ID: <907bac36-0c54-8f38-0f5e-f59196d414c6@kapsi.fi> (raw)
In-Reply-To: <CABb+yY0_dKC_cYFwwb-aeRgrx=sjv=8VLP=C6DJEecFf=v+mkQ@mail.gmail.com>

On 08/03/2018 03:54 PM, Jassi Brar wrote:
> On Mon, Jul 2, 2018 at 5:10 PM, Mikko Perttunen <mperttunen@nvidia.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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