From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [PATCH] [RFC] dmaengine: add fifo_size member Date: Thu, 6 Jun 2019 19:44:41 +0300 Message-ID: References: <1556623828-21577-1-git-send-email-spujar@nvidia.com> <20190502060446.GI3845@vkoul-mobl.Dlink> <20190502122506.GP3845@vkoul-mobl.Dlink> <3368d1e1-0d7f-f602-5b96-a978fcf4d91b@nvidia.com> <20190504102304.GZ3845@vkoul-mobl.Dlink> <20190506155046.GH3845@vkoul-mobl.Dlink> <4cab47d0-41c3-5a87-48e1-d7f085c2e091@nvidia.com> <8a5b84db-c00b-fff4-543f-69d90c245660@nvidia.com> <3f836a10-eaf3-f59b-7170-6fe937cf2e43@ti.com> <4593f37c-5e89-8559-4e80-99dbfe4235de@nvidia.com> <50e1f9ed-1ea0-38f6-1a77-febd6a3a0848@gmail.com> <4b098fb6-1a5b-1100-ae16-978a887c9535@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <4b098fb6-1a5b-1100-ae16-978a887c9535@nvidia.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Jon Hunter , Peter Ujfalusi , Sameer Pujar , Vinod Koul 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 List-Id: linux-tegra@vger.kernel.org 06.06.2019 19:32, Jon Hunter пишет: > > 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. Ah, so you need to apply the same configuration in two places. Correct? Are ADMAIF and ADMA really two different hardware blocks? Or you artificially decoupled the ADMA driver?