On Wed, Dec 02, 2015 at 03:22:04PM +0100, Moise Gergaud wrote:
> Add a helper to update only the IEC958 channel status sampling freq and
> word length parameters from an ALSA snd_pcm_runtime structure, taking
> account of the sample rate and sample size.
>
> Signed-off-by: Moise Gergaud <moise.gergaud@xxxxxx>
> Acked-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxx>
NAK.
> diff --git a/include/sound/pcm_iec958.h b/include/sound/pcm_iec958.h
> index 0eed397..0c84c69 100644
> --- a/include/sound/pcm_iec958.h
> +++ b/include/sound/pcm_iec958.h
> @@ -3,7 +3,24 @@
>
> #include <linux/types.h>
>
> +#ifdef CONFIG_SND_PCM_IEC958
> int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
> - size_t len);
> + size_t len);
> +
> +int snd_pcm_update_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
> + size_t len);
> +#else
> +int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
> + size_t len)
> +{
> + return len;
> +}
> +
> +int snd_pcm_update_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
> + size_t len)
> +{
> + return len;
> +}
Firstly, this is dangerous. If you don't have anything defined here,
then the channel status ends up being undefined.
The intention here is that if you're a user of this, then select the
config symbol. That makes providing stubs totally unnecessary and
removes this problem.
> +#endif
>
> #endif
> diff --git a/sound/core/pcm_iec958.c b/sound/core/pcm_iec958.c
> index 36b2d7a..abe3967 100644
> --- a/sound/core/pcm_iec958.c
> +++ b/sound/core/pcm_iec958.c
> @@ -11,67 +11,72 @@
> #include <sound/pcm.h>
> #include <sound/pcm_iec958.h>
>
> -/**
> - * snd_pcm_create_iec958_consumer - create consumer format IEC958 channel status
> +/*
> + * snd_pcm_update_iec958_consumer - update consumer format IEC958 channel status
> * @runtime: pcm runtime structure with ->rate filled in
> * @cs: channel status buffer, at least four bytes
> * @len: length of channel status buffer
> *
> - * Create the consumer format channel status data in @cs of maximum size
> - * @len corresponding to the parameters of the PCM runtime @runtime.
> - *
> - * Drivers may wish to tweak the contents of the buffer after creation.
> + * Update sampling frequency and word length parameters of the consumer format
> + * channel status data in @cs of maximum size @len.
> + * Values correspond to the rate and format parameters of the PCM runtime
> + * @runtime.
> *
> * Returns: length of buffer, or negative error code if something failed.
> */
> -int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
> - size_t len)
> +int snd_pcm_update_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
> + size_t len)
> {
> - unsigned int fs, ws;
> -
> if (len < 4)
> return -EINVAL;
>
> + cs[3] &= ~IEC958_AES3_CON_FS;
> +
> switch (runtime->rate) {
> + case 22050:
> + cs[3] |= IEC958_AES3_CON_FS_22050;
> + break;
> case 32000:
> - fs = IEC958_AES3_CON_FS_32000;
> + cs[3] |= IEC958_AES3_CON_FS_32000;
> break;
> case 44100:
> - fs = IEC958_AES3_CON_FS_44100;
> + cs[3] |= IEC958_AES3_CON_FS_44100;
> break;
> case 48000:
> - fs = IEC958_AES3_CON_FS_48000;
> + cs[3] |= IEC958_AES3_CON_FS_48000;
> break;
> case 88200:
> - fs = IEC958_AES3_CON_FS_88200;
> + cs[3] |= IEC958_AES3_CON_FS_88200;
> break;
> case 96000:
> - fs = IEC958_AES3_CON_FS_96000;
> + cs[3] |= IEC958_AES3_CON_FS_96000;
> break;
> case 176400:
> - fs = IEC958_AES3_CON_FS_176400;
> + cs[3] |= IEC958_AES3_CON_FS_176400;
> break;
> case 192000:
> - fs = IEC958_AES3_CON_FS_192000;
> + cs[3] |= IEC958_AES3_CON_FS_192000;
> break;
Again, I'm not happy with this change. The intention here is that we
validate all arguments before we change anything. This breaks that
principle.
--
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
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