sound/kernel-api/writing-an-alsa-driver.rst

17 and have basic linux kernel programming knowledge. This document doesn't
18 explain the general topic of linux kernel coding and doesn't cover
506 without module options don't need them.
572 This function itself doesn't allocate the data space. The data must be
579 for each component is defined in the callback pointers. Hence, you don't
617 With this method, you don't have to allocate twice. The record is
875 :c:func:`kzalloc()` automatically, so you don't have to take care of
916 I won't give details about the interrupt handler at this point, but at
968 Don't forget to call :c:func:`pci_disable_device()` before the
975 We didn't implement the hardware disabling part above. If you
984 components like PCMs and controls have already been released. You don't
1122 mode. But you don't have to care about such details in your driver. The
1424 don't have to call the destructor explicitly.
1553 standard managed buffer allocation mode, you don't need to set the
1708 your driver doesn't support mmap, this field is not
1729 callback`_. Don't mix this with ``pcm->private_data``. The
1994 If the IRQ handler is released by the card destructor, you don't need
2124 outside the PCM stream lock, hence it can't be called from the atomic
2131 This happens when the hardware doesn't generate interrupts at the period
2183 In both cases, even if more than one period has elapsed, you don't have
2325 with the period size.  By default, ALSA PCM core doesn't enforce the
2343 I won't give more details here, rather I would like to say, “Luke, use
2481 instead. In this case, you don't have to define the ``put`` callback.
2483 you can use the ``WRITE`` flag instead, and you don't need the ``get``
2725 The ALSA AC97 codec layer is a well-defined one, and you don't have to
2862 :c:func:`snd_ac97_update()` doesn't write a value if the given
2895 In some chips, the clock of the codec isn't 48000 but using a PCI clock
2967 When ``MPU401_INFO_TX_IRQ`` is set, the output stream isn't checked in
3001 handler is automatically used, hence you don't have anything else to do
3112 hardware here, but you shouldn't start transmitting/receiving data yet.
3170 timer if the hardware doesn't have a MIDI transmit interrupt.
3337 callback, you don't specify the value field for this type (the count
3432 doesn't have to call these functions explicitly in its callback any
3446 enough. This method doesn't need any extra buffers and thus is more
3598 we don't need to pre-allocate the buffers like other continuous
3699 ``pos`` are guaranteed to fit within 0 and the given size. You don't
3718 Even if the driver doesn't support PM fully but partial suspend/resume
3723 don't set the ``SNDRV_PCM_INFO_RESUME`` info flag to the PCM.
3729 ``SNDRV_PCM_TRIGGER_RESUME`` isn't needed to be handled in the trigger
3910 Also, don't forget to define the module description and the license.
4001 includes PCM, and OPL3_LIB includes HWDEP. You don't need to give