On Mon, 18 Nov 2019 20:20:41 +0100, Sridharan, Ranjani wrote: > > On Mon, Nov 18, 2019 at 10:54 AM Takashi Iwai <tiwai@xxxxxxx> 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 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
