Message-Id: <323558A8-0209-42EF-8E02-43F76D3AB6A5@lgepartner.com>
Date:   Thu, 14 May 2020 11:47:08 +0900
From:   CJ Lee <changjoon.lee@...partner.com>
To:     tiwai@...e.de
Cc:     alsa-devel@...a-project.org, linux@...lessm.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] Updated negative return values for documentation
 update.

Dear Tiwai san,

First of all, thank you very much all those years you contributed on ALSA.

Couple of days ago I emailed you over updating remark fields.
The purpose of edit was providing more error and meaning to application engineers.

For example, when snd_pcm_writei returned -EIO, application engineer didn’t understand what it means because the documentation didn’t include -EIO comment.

Would you please let me know if I need to do something to apply these changes?
I’m very new to linux community, and I thought create a patch and email to relevant recipients.
However, it looks like I’m missing something here. :)

FYI, I have not changed any code. 

Thank you.

Best regards,
CJ Lee


> 2020. 5. 12. 오후 6:05, changjoon.lee@....com 작성:
> 
> From: ChangJoon Lee <changjoon.lee@....com>
> 
> Signed-off-by: ChangJoon Lee <changjoon.lee@....com>
> ---
> src/pcm/pcm.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 54 insertions(+), 3 deletions(-)
> 
> diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
> index 1064044c..b53797a6 100644
> --- a/src/pcm/pcm.c
> +++ b/src/pcm/pcm.c
> @@ -820,6 +820,7 @@ int snd_pcm_nonblock(snd_pcm_t *pcm, int nonblock)
>  * \param sig Signal to raise: < 0 disable, 0 default (SIGIO)
>  * \param pid Process ID to signal: 0 current
>  * \return 0 on success otherwise a negative error code
> + * \return -ENOSYS Async is not supported on this PCM
>  *
>  * A signal is raised every period.
>  */
> @@ -850,6 +851,7 @@ int snd_pcm_async(snd_pcm_t *pcm, int sig, pid_t pid)
>  * \param pcm PCM handle
>  * \param info Information container
>  * \return 0 on success otherwise a negative error code
> + * \return -ENOSYS Info is not supported on this PCM
>  */
> int snd_pcm_info(snd_pcm_t *pcm, snd_pcm_info_t *info)
> {
> @@ -867,6 +869,7 @@ int snd_pcm_info(snd_pcm_t *pcm, snd_pcm_info_t *info)
>  * \param pcm PCM handle
>  * \param params Configuration space definition container
>  * \return 0 on success otherwise a negative error code
> + * \return -EBADFD PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
>  */
> int snd_pcm_hw_params_current(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
> {
> @@ -933,6 +936,7 @@ int snd_pcm_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
> /** \brief Remove PCM hardware configuration and free associated resources
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \return -ENOSYS Hw_free is not supported on this PCM
>  */
> int snd_pcm_hw_free(snd_pcm_t *pcm)
> {
> @@ -960,7 +964,9 @@ int snd_pcm_hw_free(snd_pcm_t *pcm)
>  * \param pcm PCM handle
>  * \param params Configuration container
>  * \return 0 on success otherwise a negative error code
> - *
> + * \retval -EIO PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EINVAL Incorrect parameter, avail_min cannot be 0
> + * 
>  * The software parameters can be changed at any time.
>  * The hardware parameters cannot be changed when the stream is
>  * running (active).
> @@ -1017,6 +1023,7 @@ int snd_pcm_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t *params)
>  * \param pcm PCM handle
>  * \param status Status container
>  * \return 0 on success otherwise a negative error code
> + * \return -ENOSYS Status is not supported on this PCM
>  *
>  * The function is thread-safe when built with the proper option.
>  */
> @@ -1060,7 +1067,8 @@ snd_pcm_state_t snd_pcm_state(snd_pcm_t *pcm)
>  * \brief (DEPRECATED) Synchronize stream position with hardware
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> - *
> + * \retval -EIO PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * 
>  * Note this function does not update the actual r/w pointer
>  * for applications. The function #snd_pcm_avail_update()
>  * have to be called before any mmap begin+commit operation.
> @@ -1089,6 +1097,7 @@ int snd_pcm_hwsync(snd_pcm_t *pcm)
>  * \param pcm PCM handle
>  * \param delayp Returned delay in frames
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
>  *
>  * For playback the delay is defined as the time that a frame that is written
>  * to the PCM stream shortly after this call will take to be actually
> @@ -1133,6 +1142,7 @@ int snd_pcm_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp)
>  * \brief Resume from suspend, no samples are lost
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
>  * \retval -EAGAIN resume can't be proceed immediately (audio hardware is probably still suspended)
>  * \retval -ENOSYS hardware doesn't support this feature
>  *
> @@ -1166,6 +1176,8 @@ int snd_pcm_resume(snd_pcm_t *pcm)
>  * \param avail Number of available frames when timestamp was grabbed
>  * \param tstamp Hi-res timestamp
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -ENOSYS Hi-res timestamp is not supported on this system.
>  *
>  * Note this function does not update the actual r/w pointer
>  * for applications.
> @@ -1194,6 +1206,9 @@ int snd_pcm_htimestamp(snd_pcm_t *pcm, snd_pcm_uframes_t *avail, snd_htimestamp_
>  * \brief Prepare PCM for use
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -ENOSYS Prepare is not supported on this PCM
> + * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_DISCONNECTED)
>  *
>  * The function is thread-safe when built with the proper option.
>  */
> @@ -1222,6 +1237,8 @@ int snd_pcm_prepare(snd_pcm_t *pcm)
>  * \brief Reset PCM position
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -ENOSYS Reset is not supported on this PCM
>  *
>  * Reduce PCM delay to 0.
>  *
> @@ -1249,6 +1266,8 @@ int snd_pcm_reset(snd_pcm_t *pcm)
>  * \brief Start a PCM
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED)
>  *
>  * The function is thread-safe when built with the proper option.
>  */
> @@ -1274,6 +1293,8 @@ int snd_pcm_start(snd_pcm_t *pcm)
>  * \brief Stop a PCM dropping pending frames
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED,DRAINING,SETUP or SUSPENDED)
>  *
>  * This function stops the PCM <i>immediately</i>.
>  * The pending samples on the buffer are ignored.
> @@ -1309,7 +1330,10 @@ int snd_pcm_drop(snd_pcm_t *pcm)
>  * \brief Stop a PCM preserving pending frames
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED or DRAINING,SETUP or SUSPENDED)
>  * \retval -ESTRPIPE a suspend event occurred
> + * \retval -ENOSYS Drain is not supported on this PCM
>  *
>  * For playback wait for all pending frames to be played and then stop
>  * the PCM.
> @@ -1345,6 +1369,10 @@ int snd_pcm_drain(snd_pcm_t *pcm)
>  * \param pcm PCM handle
>  * \param enable 0 = resume, 1 = pause
>  * \return 0 on success otherwise a negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED or DRAINING)
> + * \retval -ESTRPIPE a suspend event occurred
> + * \retval -ENOSYS Pause is not supported on this PCM
>  *
>  * Note that this function works only on the hardware which supports
>  * pause feature.  You can check it via \link ::snd_pcm_hw_params_can_pause() \endlink
> @@ -1377,6 +1405,10 @@ int snd_pcm_pause(snd_pcm_t *pcm, int enable)
>  * \brief Get safe count of frames which can be rewinded
>  * \param pcm PCM handle
>  * \return a positive number of frames or negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED or DRAINING)
> + * \retval -ESTRPIPE a suspend event occurred
> + * \retval -ENOSYS Rewindable is not supported on this PCM
>  *
>  * Note: The snd_pcm_rewind() can accept bigger value than returned
>  * by this function. But it is not guaranteed that output stream
> @@ -1412,6 +1444,9 @@ snd_pcm_sframes_t snd_pcm_rewindable(snd_pcm_t *pcm)
>  * \param frames wanted displacement in frames
>  * \return a positive number for actual displacement otherwise a
>  * negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED or DRAINING)
> + * \retval -ENOSYS Rewind is not supported on this PCM
>  *
>  * The function is thread-safe when built with the proper option.
>  */
> @@ -1443,6 +1478,9 @@ snd_pcm_sframes_t snd_pcm_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
>  * \brief Get safe count of frames which can be forwarded
>  * \param pcm PCM handle
>  * \return a positive number of frames or negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED or DRAINING)
> + * \retval -ENOSYS Forwardable is not supported on this PCM
>  *
>  * Note: The snd_pcm_forward() can accept bigger value than returned
>  * by this function. But it is not guaranteed that output stream
> @@ -1478,6 +1516,9 @@ snd_pcm_sframes_t snd_pcm_forwardable(snd_pcm_t *pcm)
>  * \param frames wanted skip in frames
>  * \return a positive number for actual skip otherwise a negative error code
>  * \retval 0 means no action
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EBADFD PCM is not in the right state (Should be PREPARED,RUNNING,XRUN,PAUSED or DRAINING)
> + * \retval -ENOSYS Forward is not supported on this PCM
>  *
>  * The function is thread-safe when built with the proper option.
>  */
> @@ -1517,6 +1558,8 @@ use_default_symbol_version(__snd_pcm_forward, snd_pcm_forward, ALSA_0.9.0rc8);
>  * \param size frames to be written
>  * \return a positive number of frames actually written otherwise a
>  * negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EINVAL Access type is not Interleave type.
>  * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
>  * \retval -EPIPE an underrun occurred
>  * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
> @@ -1556,6 +1599,8 @@ snd_pcm_sframes_t snd_pcm_writei(snd_pcm_t *pcm, const void *buffer, snd_pcm_ufr
>  * \param size frames to be written
>  * \return a positive number of frames actually written otherwise a
>  * negative error code
> + * \retval -EIO    PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EINVAL Access type is not Non-Interleave type.
>  * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
>  * \retval -EPIPE an underrun occurred
>  * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
> @@ -1595,6 +1640,8 @@ snd_pcm_sframes_t snd_pcm_writen(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t
>  * \param size frames to be read
>  * \return a positive number of frames actually read otherwise a
>  * negative error code
> + * \retval -EIO PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EINVAL Access type is not Interleave type.
>  * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
>  * \retval -EPIPE an overrun occurred
>  * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
> @@ -1634,6 +1681,8 @@ snd_pcm_sframes_t snd_pcm_readi(snd_pcm_t *pcm, void *buffer, snd_pcm_uframes_t
>  * \param size frames to be read
>  * \return a positive number of frames actually read otherwise a
>  * negative error code
> + * \retval -EIO PCM has not been setup (PCM isn't configured yet, or lifecycle of PCM has been ended)
> + * \retval -EINVAL Access type is not Non-Interleave type.
>  * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
>  * \retval -EPIPE an overrun occurred
>  * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
> @@ -1669,8 +1718,9 @@ snd_pcm_sframes_t snd_pcm_readn(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t s
> /**
>  * \brief Link two PCMs
>  * \param pcm1 first PCM handle
> - * \param pcm2 first PCM handle
> + * \param pcm2 second PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -ENOSYS Link is not supported on pcm1
>  *
>  * The two PCMs will start/stop/prepare in sync.
>  */ 
> @@ -1691,6 +1741,7 @@ int snd_pcm_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
>  * \brief Remove a PCM from a linked group
>  * \param pcm PCM handle
>  * \return 0 on success otherwise a negative error code
> + * \retval -ENOSYS Unlink is not supported on this PCM.
>  */
> int snd_pcm_unlink(snd_pcm_t *pcm)
> {
> -- 
> 2.26.2
> 

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