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From: Jon Hunter <jonathanh@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.com>,
	Peter Ujfalusi <peter.ujfalusi@ti.com>,
	Sameer Pujar <spujar@nvidia.com>, Vinod Koul <vkoul@kernel.org>
Cc: <dan.j.williams@intel.com>, <tiwai@suse.com>,
	<dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<sharadg@nvidia.com>, <rlokhande@nvidia.com>,
	<dramesh@nvidia.com>, <mkumard@nvidia.com>,
	linux-tegra <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH] [RFC] dmaengine: add fifo_size member
Date: Thu, 6 Jun 2019 17:32:37 +0100
Message-ID: <4b098fb6-1a5b-1100-ae16-978a887c9535@nvidia.com> (raw)
In-Reply-To: <50e1f9ed-1ea0-38f6-1a77-febd6a3a0848@gmail.com>


On 06/06/2019 16:18, Dmitry Osipenko wrote:

...

>>> If I understood everything correctly, the FIFO buffer is shared among
>>> all of the ADMA clients and hence it should be up to the ADMA driver to
>>> manage the quotas of the clients. So if there is only one client that
>>> uses ADMA at a time, then this client will get a whole FIFO buffer, but
>>> once another client starts to use ADMA, then the ADMA driver will have
>>> to reconfigure hardware to split the quotas.
>>
>> The FIFO quotas are managed by the ADMAIF driver (does not exist in
>> mainline currently but we are working to upstream this) because it is
>> this device that owns and needs to configure the FIFOs. So it is really
>> a means to pass the information from the ADMAIF to the ADMA.
> 
> So you'd want to reserve a larger FIFO for an audio channel that has a
> higher audio rate since it will perform reads more often. You could also
> prioritize one channel over the others, like in a case of audio call for
> example.
> 
> Is the shared buffer smaller than may be needed by clients in a worst
> case scenario? If you could split the quotas statically such that each
> client won't ever starve, then seems there is no much need in the
> dynamic configuration.

Actually, this is still very much relevant for the static case. Even if
we defined a static configuration of the FIFO mapping in the ADMAIF
driver we still need to pass this information to the ADMA. I don't
really like the idea of having it statically defined in two different
drivers.

Jon

-- 
nvpublic

  reply index

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-30 11:30 Sameer Pujar
2019-04-30 11:30 ` [PATCH] " Sameer Pujar
2019-05-02  6:04 ` Vinod Koul
2019-05-02  6:04   ` [PATCH] " Vinod Koul
2019-05-02 10:53   ` Sameer Pujar
2019-05-02 12:25     ` Vinod Koul
2019-05-02 13:29       ` Sameer Pujar
2019-05-03 19:10         ` Peter Ujfalusi
2019-05-04 10:23         ` Vinod Koul
2019-05-06 13:04           ` Sameer Pujar
2019-05-06 15:50             ` Vinod Koul
2019-06-06  3:49               ` Sameer Pujar
2019-06-06  6:00                 ` Peter Ujfalusi
2019-06-06  6:41                   ` Sameer Pujar
2019-06-06  7:14                     ` Jon Hunter
2019-06-06 10:22                       ` Peter Ujfalusi
2019-06-06 10:49                         ` Jon Hunter
2019-06-06 11:54                           ` Peter Ujfalusi
2019-06-06 12:37                             ` Jon Hunter
2019-06-06 13:45                               ` Dmitry Osipenko
2019-06-06 13:55                                 ` Dmitry Osipenko
2019-06-06 14:26                                   ` Jon Hunter
2019-06-06 14:36                                     ` Jon Hunter
2019-06-06 14:36                                     ` Dmitry Osipenko
2019-06-06 14:47                                       ` Jon Hunter
2019-06-06 14:25                                 ` Jon Hunter
2019-06-06 15:18                                   ` Dmitry Osipenko
2019-06-06 16:32                                     ` Jon Hunter [this message]
2019-06-06 16:44                                       ` Dmitry Osipenko
2019-06-06 16:53                                         ` Jon Hunter
2019-06-06 17:25                                           ` Dmitry Osipenko
2019-06-06 17:56                                             ` Dmitry Osipenko
2019-06-07  9:24                                             ` Jon Hunter
2019-06-07  5:50                               ` Peter Ujfalusi
2019-06-07  9:18                                 ` Jon Hunter
2019-06-07 10:27                                   ` Jon Hunter
2019-06-07 12:17                                     ` Peter Ujfalusi
2019-06-07 12:58                                       ` Jon Hunter
2019-06-07 13:35                                         ` Peter Ujfalusi
2019-06-07 20:53                                           ` Dmitry Osipenko
2019-06-10  8:01                                             ` Jon Hunter
2019-06-10  7:59                                           ` Jon Hunter
2019-06-13  4:43                 ` Vinod Koul
2019-06-17  7:07                   ` Sameer Pujar
2019-06-18  4:33                     ` Vinod Koul
2019-06-20 10:29                       ` Sameer Pujar
2019-06-24  6:26                         ` Vinod Koul
2019-06-25  2:57                           ` Sameer Pujar
2019-07-05  6:15                             ` Sameer Pujar
2019-07-15 15:42                               ` Sameer Pujar
2019-07-19  5:04                               ` Vinod Koul
2019-07-23  5:54                                 ` Sameer Pujar
2019-07-29  6:10                                   ` Vinod Koul
2019-07-31  9:48                                     ` Jon Hunter
2019-07-31 15:16                                       ` Vinod Koul
2019-08-02  8:51                                         ` Jon Hunter
2019-08-08 12:38                                           ` Vinod Koul
2019-08-19 15:56                                             ` Jon Hunter
2019-08-20 11:05                                               ` Vinod Koul
2019-09-16  9:02                                                 ` Sameer Pujar

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