On Thu, 20 May 2021 15:59:02 +0200, <Codrin.Ciubotariu@xxxxxxxxxxxxx> wrote: > > On 19.05.2021 18:41, Takashi Iwai wrote: > > On Wed, 19 May 2021 17:08:10 +0200, > > <Codrin.Ciubotariu@xxxxxxxxxxxxx> wrote: > >> > >> On 19.05.2021 17:15, Takashi Iwai wrote: > >>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > >>> > >>> On Wed, 19 May 2021 12:48:36 +0200, > >>> Codrin Ciubotariu wrote: > >>>> > >>>> This patchset adds a different snd_pcm_runtime in the BE's substream, > >>>> replacing the FE's snd_pcm_runtime. With a different structure, the BE > >>>> HW capabilities and constraints will no longer merge with the FE ones. > >>>> This allows for error detection if the be_hw_params_fixup() applies HW > >>>> parameters not supported by the BE DAIs. Also, it calculates values > >>>> needed for mem-to-dev/dev-to-mem DMA transfers, such as buffer size and > >>>> period size, if needed. > >>>> > >>>> The first 4 patches are preparatory patches, that just group and export > >>>> functions used to allocate and initialize the snd_pcm_runtime. Also, the > >>>> functions that set and apply the HW constraints are exported. > >>>> The 5th patch does (almost) everything need to create the new snd_pcm_runtime > >>>> for BEs, which includes allocation, initializing the HW capabilities, > >>>> HW constraints and HW parameters. The BE HW parameters are no longer > >>>> copied from the FE. They are recalculated, based on HW capabilities, > >>>> constraints and the be_hw_params_fixup() callback. > >>>> The 6th and last patch basically adds support for the PCM generic > >>>> dmaengine to be used as a platform driver for BE DAI links. It allocates > >>>> a buffer, needed by the DMA transfers that do not support dev-to-dev > >>>> transfers between FE and BE DAIs. > >>>> > >>>> This is a superset of > >>>> https://mailman.alsa-project.org/pipermail/alsa-devel/2021-March/182630.html > >>>> which only handles the BE HW constraints. This patchset aims to be more > >>>> complete, defining a a snd_pcm_runtime between each FE and BE and can > >>>> be used between any DAI link connection. I am sure I am not handling all > >>>> the needed members of snd_pcm_runtime (such as handling > >>>> struct snd_pcm_mmap_status *status), but I would like to have your > >>>> feedback regarding this idea. > >>> > >>> I'm also concerned about the handling of other fields in runtime > >>> object, maybe allocating a complete runtime object for each BE is an > >>> overkill and fragile. Could it be rather only hw_constraints to be > >>> unique for each BE, instead? > >> > >> I tried with only the hw constraints in the previous patchset and it's > >> difficult to handle the snd_pcm_hw_rule_add() calls, without changing > >> the function's declaration. This solution requires no changes to > >> constraints API, nor to their 'clients'. I agree that handling all the > >> runtime fields might be over-complicated. From what I see, the scary > >> ones are used to describe the buffer and the status of the transfers. I > >> do not think there are BEs that use these values at this moment (the FE > >> ones). I think that the HW params, private section, hardware description > >> and maybe DMA members (at least in my case) are mostly needed by BEs. > > > > OK, I'll check your previous series again, but my gut feeling is for > > pursuit to the hw_constraints hacks. e.g. we may split > > snd_pcm_hw_constraints and snd_pcm_hw_rule, too, if that matters. > > Something like adding snd_pcm_hw_rule directly under > snd_pcm_runtime, to store the BE constraints? It could work, but I think > we should also be able to remove rules, if one BE gets disconnected. > This means that we will need a way to identify or separate them, for > each BE, right? Well, if each BE needs a different set of hw constraint rules, it needs its own unique copies instead of sharing the rules. Is it your requirement? Takashi
