diff options
Diffstat (limited to 'Documentation/DocBook/writing-an-alsa-driver.tmpl')
| -rw-r--r-- | Documentation/DocBook/writing-an-alsa-driver.tmpl | 144 |
1 files changed, 62 insertions, 82 deletions
diff --git a/Documentation/DocBook/writing-an-alsa-driver.tmpl b/Documentation/DocBook/writing-an-alsa-driver.tmpl index fb32aead5a0..6f639d9530b 100644 --- a/Documentation/DocBook/writing-an-alsa-driver.tmpl +++ b/Documentation/DocBook/writing-an-alsa-driver.tmpl @@ -468,8 +468,6 @@ return err; } - snd_card_set_dev(card, &pci->dev); - *rchip = chip; return 0; } @@ -492,7 +490,8 @@ } /* (2) */ - err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card); + err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE, + 0, &card); if (err < 0) return err; @@ -591,7 +590,8 @@ struct snd_card *card; int err; .... - err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card); + err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE, + 0, &card); ]]> </programlisting> </informalexample> @@ -809,28 +809,34 @@ <para> As mentioned above, to create a card instance, call - <function>snd_card_create()</function>. + <function>snd_card_new()</function>. <informalexample> <programlisting> <![CDATA[ struct snd_card *card; int err; - err = snd_card_create(index, id, module, extra_size, &card); + err = snd_card_new(&pci->dev, index, id, module, extra_size, &card); ]]> </programlisting> </informalexample> </para> <para> - The function takes five arguments, the card-index number, the - id string, the module pointer (usually + The function takes six arguments: the parent device pointer, + the card-index number, the id string, the module pointer (usually <constant>THIS_MODULE</constant>), the size of extra-data space, and the pointer to return the card instance. The extra_size argument is used to allocate card->private_data for the chip-specific data. Note that these data - are allocated by <function>snd_card_create()</function>. + are allocated by <function>snd_card_new()</function>. + </para> + + <para> + The first argument, the pointer of struct + <structname>device</structname>, specifies the parent device. + For PCI devices, typically &pci-> is passed there. </para> </section> @@ -871,9 +877,8 @@ <para> This function itself doesn't allocate the data space. The data must be allocated manually beforehand, and its pointer is passed - as the argument. This pointer is used as the - (<parameter>chip</parameter> identifier in the above example) - for the instance. + as the argument. This pointer (<parameter>chip</parameter> in the + above example) is used as the identifier for the instance. </para> <para> @@ -917,16 +922,16 @@ </para> <section id="card-management-chip-specific-snd-card-new"> - <title>1. Allocating via <function>snd_card_create()</function>.</title> + <title>1. Allocating via <function>snd_card_new()</function>.</title> <para> As mentioned above, you can pass the extra-data-length - to the 4th argument of <function>snd_card_create()</function>, i.e. + to the 5th argument of <function>snd_card_new()</function>, i.e. <informalexample> <programlisting> <![CDATA[ - err = snd_card_create(index[dev], id[dev], THIS_MODULE, - sizeof(struct mychip), &card); + err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE, + sizeof(struct mychip), &card); ]]> </programlisting> </informalexample> @@ -955,7 +960,7 @@ <para> After allocating a card instance via - <function>snd_card_create()</function> (with + <function>snd_card_new()</function> (with <constant>0</constant> on the 4th arg), call <function>kzalloc()</function>. @@ -964,7 +969,8 @@ <![CDATA[ struct snd_card *card; struct mychip *chip; - err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card); + err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE, + 0, &card); ..... chip = kzalloc(sizeof(*chip), GFP_KERNEL); ]]> @@ -1171,8 +1177,6 @@ return err; } - snd_card_set_dev(card, &pci->dev); - *rchip = chip; return 0; } @@ -1527,30 +1531,6 @@ </section> - <section id="pci-resource-device-struct"> - <title>Registration of Device Struct</title> - <para> - At some point, typically after calling <function>snd_device_new()</function>, - you need to register the struct <structname>device</structname> of the chip - you're handling for udev and co. ALSA provides a macro for compatibility with - older kernels. Simply call like the following: - <informalexample> - <programlisting> -<![CDATA[ - snd_card_set_dev(card, &pci->dev); -]]> - </programlisting> - </informalexample> - so that it stores the PCI's device pointer to the card. This will be - referred by ALSA core functions later when the devices are registered. - </para> - <para> - In the case of non-PCI, pass the proper device struct pointer of the BUS - instead. (In the case of legacy ISA without PnP, you don't have to do - anything.) - </para> - </section> - <section id="pci-resource-entries"> <title>PCI Entries</title> <para> @@ -2304,7 +2284,7 @@ struct _snd_pcm_runtime { <constant>SNDRV_PCM_INFO_XXX</constant>. Here, at least, you have to specify whether the mmap is supported and which interleaved format is supported. - When the is supported, add the + When the hardware supports mmap, add the <constant>SNDRV_PCM_INFO_MMAP</constant> flag here. When the hardware supports the interleaved or the non-interleaved formats, <constant>SNDRV_PCM_INFO_INTERLEAVED</constant> or @@ -2898,7 +2878,7 @@ struct _snd_pcm_runtime { <para> When the pcm supports the pause operation (given in the info - field of the hardware table), the <constant>PAUSE_PUSE</constant> + field of the hardware table), the <constant>PAUSE_PUSH</constant> and <constant>PAUSE_RELEASE</constant> commands must be handled here, too. The former is the command to pause the pcm, and the latter to restart the pcm again. @@ -3085,7 +3065,7 @@ struct _snd_pcm_runtime { <section id="pcm-interface-interrupt-handler-timer"> <title>High frequency timer interrupts</title> <para> - This happense when the hardware doesn't generate interrupts + This happens when the hardware doesn't generate interrupts at the period boundary but issues timer interrupts at a fixed timer rate (e.g. es1968 or ymfpci drivers). In this case, you need to check the current hardware @@ -3251,18 +3231,19 @@ struct _snd_pcm_runtime { <title>Example of Hardware Constraints for Channels</title> <programlisting> <![CDATA[ - static int hw_rule_format_by_channels(struct snd_pcm_hw_params *params, + static int hw_rule_channels_by_format(struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule) { struct snd_interval *c = hw_param_interval(params, - SNDRV_PCM_HW_PARAM_CHANNELS); + SNDRV_PCM_HW_PARAM_CHANNELS); struct snd_mask *f = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT); - struct snd_mask fmt; + struct snd_interval ch; - snd_mask_any(&fmt); /* Init the struct */ - if (c->min < 2) { - fmt.bits[0] &= SNDRV_PCM_FMTBIT_S16_LE; - return snd_mask_refine(f, &fmt); + snd_interval_any(&ch); + if (f->bits[0] == SNDRV_PCM_FMTBIT_S16_LE) { + ch.min = ch.max = 1; + ch.integer = 1; + return snd_interval_refine(c, &ch); } return 0; } @@ -3278,35 +3259,35 @@ struct _snd_pcm_runtime { <programlisting> <![CDATA[ snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS, - hw_rule_channels_by_format, 0, SNDRV_PCM_HW_PARAM_FORMAT, - -1); + hw_rule_channels_by_format, NULL, + SNDRV_PCM_HW_PARAM_FORMAT, -1); ]]> </programlisting> </informalexample> </para> <para> - The rule function is called when an application sets the number of - channels. But an application can set the format before the number of - channels. Thus you also need to define the inverse rule: + The rule function is called when an application sets the PCM + format, and it refines the number of channels accordingly. + But an application may set the number of channels before + setting the format. Thus you also need to define the inverse rule: <example> - <title>Example of Hardware Constraints for Channels</title> + <title>Example of Hardware Constraints for Formats</title> <programlisting> <![CDATA[ - static int hw_rule_channels_by_format(struct snd_pcm_hw_params *params, + static int hw_rule_format_by_channels(struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule) { struct snd_interval *c = hw_param_interval(params, - SNDRV_PCM_HW_PARAM_CHANNELS); + SNDRV_PCM_HW_PARAM_CHANNELS); struct snd_mask *f = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT); - struct snd_interval ch; + struct snd_mask fmt; - snd_interval_any(&ch); - if (f->bits[0] == SNDRV_PCM_FMTBIT_S16_LE) { - ch.min = ch.max = 1; - ch.integer = 1; - return snd_interval_refine(c, &ch); + snd_mask_any(&fmt); /* Init the struct */ + if (c->min < 2) { + fmt.bits[0] &= SNDRV_PCM_FMTBIT_S16_LE; + return snd_mask_refine(f, &fmt); } return 0; } @@ -3321,8 +3302,8 @@ struct _snd_pcm_runtime { <programlisting> <![CDATA[ snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT, - hw_rule_format_by_channels, 0, SNDRV_PCM_HW_PARAM_CHANNELS, - -1); + hw_rule_format_by_channels, NULL, + SNDRV_PCM_HW_PARAM_CHANNELS, -1); ]]> </programlisting> </informalexample> @@ -5715,7 +5696,7 @@ struct _snd_pcm_runtime { suspending the PCM operations via <function>snd_pcm_suspend_all()</function> or <function>snd_pcm_suspend()</function>. It means that the PCM - streams are already stoppped when the register snapshot is + streams are already stopped when the register snapshot is taken. But, remember that you don't have to restart the PCM stream in the resume callback. It'll be restarted via trigger call with <constant>SNDRV_PCM_TRIGGER_RESUME</constant> @@ -5740,7 +5721,8 @@ struct _snd_pcm_runtime { struct mychip *chip; int err; .... - err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card); + err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE, + 0, &card); .... chip = kzalloc(sizeof(*chip), GFP_KERNEL); .... @@ -5752,7 +5734,7 @@ struct _snd_pcm_runtime { </informalexample> When you created the chip data with - <function>snd_card_create()</function>, it's anyway accessible + <function>snd_card_new()</function>, it's anyway accessible via <structfield>private_data</structfield> field. <informalexample> @@ -5766,8 +5748,8 @@ struct _snd_pcm_runtime { struct mychip *chip; int err; .... - err = snd_card_create(index[dev], id[dev], THIS_MODULE, - sizeof(struct mychip), &card); + err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE, + sizeof(struct mychip), &card); .... chip = card->private_data; .... @@ -6164,14 +6146,12 @@ struct _snd_pcm_runtime { <para> The macro takes an conditional expression to evaluate. - When <constant>CONFIG_SND_DEBUG</constant>, is set, the - expression is actually evaluated. If it's non-zero, it shows - the warning message such as + When <constant>CONFIG_SND_DEBUG</constant>, is set, if the + expression is non-zero, it shows the warning message such as <computeroutput>BUG? (xxx)</computeroutput> - normally followed by stack trace. It returns the evaluated - value. - When no <constant>CONFIG_SND_DEBUG</constant> is set, this - macro always returns zero. + normally followed by stack trace. + + In both cases it returns the evaluated value. </para> </section> |