78 lines
2.9 KiB
Diff
78 lines
2.9 KiB
Diff
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From 1eddf1f918845d1e6cbcac5516319b20cad80f2f Mon Sep 17 00:00:00 2001
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From: Adam Goode <agoode@google.com>
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Date: Tue, 3 Jan 2017 08:33:42 -0500
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Subject: [PATCH 09/43] seq: improve documentation about new get pid/card
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functions
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Document the technique for determining if the running kernel supports
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the new snd_seq_client_info_get_pid and snd_seq_client_info_get_card
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functions. Also add a little information about how to use these
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functions and add some cross references.
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Signed-off-by: Adam Goode <agoode@google.com>
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Signed-off-by: Takashi Iwai <tiwai@suse.de>
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---
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src/seq/seq.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
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1 file changed, 42 insertions(+), 2 deletions(-)
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--- a/src/seq/seq.c
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+++ b/src/seq/seq.c
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@@ -1530,7 +1530,25 @@ int snd_seq_client_info_get_error_bounce
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* \param info client_info container
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* \return card number or -1 if value is not available.
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*
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- * Only available for SND_SEQ_KERNEL_CLIENT clients.
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+ * Only available for #SND_SEQ_KERNEL_CLIENT clients.
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+ *
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+ * The card number can be used to query state about the hardware
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+ * device providing this client, by concatenating <code>"hw:CARD="</code>
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+ * with the card number and using it as the <code>name</code> parameter
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+ * to #snd_ctl_open().
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+ *
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+ * \note
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+ * The return value of -1 is returned for two different conditions: when the
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+ * running kernel does not support this operation, and when the client
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+ * does not have a hardware card attached. See
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+ * #snd_seq_client_info_get_pid() for a way to determine if the
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+ * currently running kernel has support for this operation.
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+ *
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+ * \sa snd_seq_client_info_get_pid(),
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+ * snd_card_get_name(),
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+ * snd_card_get_longname(),
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+ * snd_ctl_open(),
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+ * snd_ctl_card_info()
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*/
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int snd_seq_client_info_get_card(const snd_seq_client_info_t *info)
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{
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@@ -1543,7 +1561,29 @@ int snd_seq_client_info_get_card(const s
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* \param info client_info container
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* \return pid or -1 if value is not available.
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*
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- * Only available for SND_SEQ_USER_CLIENT clients.
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+ * Only available for #SND_SEQ_USER_CLIENT clients.
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+ *
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+ * \note
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+ * The functionality for getting a client's PID and getting a
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+ * client's card was added to the kernel at the same time, so you can
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+ * use this function to determine if the running kernel
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+ * supports reporting these values. If your own client has a valid
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+ * PID as reported by this function, then the running kernel supports
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+ * both #snd_seq_client_info_get_card() and #snd_seq_client_info_get_pid().
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+ *
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+ * \note
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+ * Example code for determining kernel support:
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+ * \code
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+ * int is_get_card_or_pid_supported(snd_seq_t *seq)
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+ * {
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+ * snd_seq_client_info_t *my_client_info;
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+ * snd_seq_client_info_alloca(&my_client_info);
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+ * snd_seq_get_client_info(seq, my_client_info);
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+ * return snd_seq_client_info_get_pid(my_client_info) != -1;
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+ * }
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+ * \endcode
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+ *
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+ * \sa snd_seq_client_info_get_card()
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*/
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int snd_seq_client_info_get_pid(const snd_seq_client_info_t *info)
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{
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