From: Takashi Iwai <tiwai@suse.de>
To: "Sridharan, Ranjani" <ranjani.sridharan@intel.com>
Cc: Linux-ALSA <alsa-devel@alsa-project.org>,
Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Subject: Re: [alsa-devel] [PATCH 7/8] ALSA: pcm: Add card sync_irq field
Date: Mon, 18 Nov 2019 20:49:29 +0100 [thread overview]
Message-ID: <s5hpnhpyng6.wl-tiwai@suse.de> (raw)
In-Reply-To: <CAFQqKeWgqHwrCSSbLrkuCHkBww2g4dsBcF93SDN_ZK_-KSe5tg@mail.gmail.com>
On Mon, 18 Nov 2019 20:20:41 +0100,
Sridharan, Ranjani wrote:
>
> On Mon, Nov 18, 2019 at 10:54 AM Takashi Iwai <tiwai@suse.de> wrote:
>
> On Mon, 18 Nov 2019 17:38:49 +0100,
> Pierre-Louis Bossart wrote:
> >
> >
> >
> > On 11/17/19 2:53 AM, Takashi Iwai wrote:
> > > Many PCI and other drivers performs snd_pcm_period_elapsed() simply in
> > > its interrupt handler, so the sync_stop operation is just to call
> > > synchronize_irq(). Instead of putting this call multiple times,
> > > introduce the common card->sync_irq field. When this field is set,
> > > PCM core performs synchronize_irq() for sync-stop operation. Each
> > > driver just needs to copy its local IRQ number to card->sync_irq, and
> > > that's all we need.
> >
> > Maybe a red-herring or complete non-sense, but I wonder if this is
> > going to get in the way of Ranjani's multi-client work, where we could
> > have multiple cards created but with a single IRQ handled by the
> > parent PCI device?
> >
> > Ranjani, you may want to double-check this and chime in, thanks!
>
> The synchronize_irq() is fairly safe to call multiple times, and I
> don't think any problem by invoking it for multi-clients sharing the
> same IRQ. For example, Digigram miXart driver creates multiple card
> objects from a single PCI entry, and I already thought of that
> possibility; they set the same card->sync_irq value to all card
> objects, which eventually will call synchronize_irq() multiple times.
> From the performance POV, this shouldn't be a big problem, because
> the place calling this is only at hw_params, prepare and hw_free,
> neither are hot-path.
>
> Thanks for the clarification, Takashi. But just wondering how would one pass
> on the sync_irq when the snd_card is created? Typically in the case of the
> Intel platforms, the card->dev points to the platform device for the machine
> driver that registers the card and the PCI device is the parent of the machine
> drv platform device.
It's completely up to the driver implementation :)
You can implement the own sync_stop ops if that's easier, too.
In general, the driver can set up card->sync_irq when the
request_irq() or its variant is called.
Takashi
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next prev parent reply other threads:[~2019-11-18 19:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-17 8:53 [alsa-devel] [PATCH 0/8] ALSA: pcm: API cleanups and extensions Takashi Iwai
2019-11-17 8:53 ` [alsa-devel] [PATCH 1/8] ALSA: pcm: Introduce managed buffer allocation mode Takashi Iwai
2019-11-18 16:24 ` Pierre-Louis Bossart
2019-11-18 18:46 ` Takashi Iwai
2019-11-17 8:53 ` [alsa-devel] [PATCH 2/8] ALSA: docs: Update for " Takashi Iwai
2019-11-17 8:53 ` [alsa-devel] [PATCH 3/8] ALSA: pcm: Allow NULL ioctl ops Takashi Iwai
2019-11-17 8:53 ` [alsa-devel] [PATCH 4/8] ALSA: docs: Update document about the default PCM " Takashi Iwai
2019-11-17 8:53 ` [alsa-devel] [PATCH 5/8] ALSA: pcm: Move PCM_RUNTIME_CHECK() macro into local header Takashi Iwai
2019-11-17 9:42 ` kbuild test robot
2019-11-17 10:05 ` Takashi Iwai
2019-11-17 10:28 ` kbuild test robot
2019-11-17 8:53 ` [alsa-devel] [PATCH 6/8] ALSA: pcm: Add the support for sync-stop operation Takashi Iwai
2019-11-18 16:33 ` Pierre-Louis Bossart
2019-11-18 18:47 ` Takashi Iwai
2019-11-17 8:53 ` [alsa-devel] [PATCH 7/8] ALSA: pcm: Add card sync_irq field Takashi Iwai
2019-11-18 16:38 ` Pierre-Louis Bossart
2019-11-18 18:52 ` Takashi Iwai
2019-11-18 19:20 ` Sridharan, Ranjani
2019-11-18 19:49 ` Takashi Iwai [this message]
2019-11-18 19:55 ` Sridharan, Ranjani
2019-11-18 20:40 ` Takashi Iwai
2019-11-18 23:47 ` Ranjani Sridharan
2019-11-19 6:44 ` Takashi Iwai
2019-11-19 7:40 ` Ranjani Sridharan
2019-11-19 8:24 ` Takashi Iwai
2019-11-19 9:39 ` Takashi Iwai
2019-11-19 16:36 ` Ranjani Sridharan
2019-11-19 21:27 ` Takashi Iwai
2019-11-19 21:43 ` Sridharan, Ranjani
2019-11-21 19:22 ` Sridharan, Ranjani
2019-11-21 20:34 ` Takashi Iwai
2019-11-21 20:46 ` Sridharan, Ranjani
2019-11-21 21:13 ` Takashi Iwai
2019-11-21 21:17 ` Sridharan, Ranjani
2019-11-21 21:28 ` Takashi Iwai
2019-11-21 21:45 ` Sridharan, Ranjani
2019-11-22 4:08 ` Jie, Yang
2019-11-17 8:53 ` [alsa-devel] [PATCH 8/8] ALSA: docs: Update about the new PCM sync_stop ops Takashi Iwai
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