diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/writing-an-alsa-driver.tmpl | 36 |
1 files changed, 21 insertions, 15 deletions
diff --git a/Documentation/DocBook/writing-an-alsa-driver.tmpl b/Documentation/DocBook/writing-an-alsa-driver.tmpl index 598c22f3b3ac..5de23c007078 100644 --- a/Documentation/DocBook/writing-an-alsa-driver.tmpl +++ b/Documentation/DocBook/writing-an-alsa-driver.tmpl @@ -4288,7 +4288,7 @@ struct _snd_pcm_runtime { <![CDATA[ struct snd_rawmidi *rmidi; snd_mpu401_uart_new(card, 0, MPU401_HW_MPU401, port, info_flags, - irq, irq_flags, &rmidi); + irq, &rmidi); ]]> </programlisting> </informalexample> @@ -4343,6 +4343,13 @@ struct _snd_pcm_runtime { by itself to start processing the output stream in the irq handler. </para> + <para> + If the MPU-401 interface shares its interrupt with the other logical + devices on the card, set <constant>MPU401_INFO_IRQ_HOOK</constant> + (see <link linkend="midi-interface-interrupt-handler"><citetitle> + below</citetitle></link>). + </para> + <para> Usually, the port address corresponds to the command port and port + 1 corresponds to the data port. If not, you may change @@ -4375,14 +4382,12 @@ struct _snd_pcm_runtime { </para> <para> - The 6th argument specifies the irq number for UART. If the irq - is already allocated, pass 0 to the 7th argument - (<parameter>irq_flags</parameter>). Otherwise, pass the flags - for irq allocation - (<constant>SA_XXX</constant> bits) to it, and the irq will be - reserved by the mpu401-uart layer. If the card doesn't generate - UART interrupts, pass -1 as the irq number. Then a timer - interrupt will be invoked for polling. + The 6th argument specifies the ISA irq number that will be + allocated. If no interrupt is to be allocated (because your + code is already allocating a shared interrupt, or because the + device does not use interrupts), pass -1 instead. + For a MPU-401 device without an interrupt, a polling timer + will be used instead. </para> </section> @@ -4390,12 +4395,13 @@ struct _snd_pcm_runtime { <title>Interrupt Handler</title> <para> When the interrupt is allocated in - <function>snd_mpu401_uart_new()</function>, the private - interrupt handler is used, hence you don't have anything else to do - than creating the mpu401 stuff. Otherwise, you have to call - <function>snd_mpu401_uart_interrupt()</function> explicitly when - a UART interrupt is invoked and checked in your own interrupt - handler. + <function>snd_mpu401_uart_new()</function>, an exclusive ISA + interrupt handler is automatically used, hence you don't have + anything else to do than creating the mpu401 stuff. Otherwise, you + have to set <constant>MPU401_INFO_IRQ_HOOK</constant>, and call + <function>snd_mpu401_uart_interrupt()</function> explicitly from your + own interrupt handler when it has determined that a UART interrupt + has occurred. </para> <para> |