Re: [PATCH v14 03/10] drm/edid: Add cea_sad helpers for freq/length

Rex-BC Chen
2022-07-14T11:19:26Z

On Thu, 2022-07-14 at 13:12 +0200, AngeloGioacchino Del Regno wrote:
> Il 12/07/22 13:12, Bo-Chen Chen ha scritto:
> > From: Guillaume Ranquet <granquet@baylibre.com>
> >
> > This patch adds two helper functions that extract the frequency and
> > word
> > length from a struct cea_sad.
> >
> > For these helper functions new defines are added that help
> > translate the
> > 'freq' and 'byte2' fields into real numbers.
> >
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> > ---
> > drivers/gpu/drm/drm_edid.c | 73
> > ++++++++++++++++++++++++++++++++++++++
> > include/drm/drm_edid.h | 14 ++++++++
> > 2 files changed, 87 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c
> > b/drivers/gpu/drm/drm_edid.c
> > index bc43e1b32092..79316d7f1fd8 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -4916,6 +4916,79 @@ int drm_edid_to_speaker_allocation(const
> > struct edid *edid, u8 **sadb)
> > }
> > EXPORT_SYMBOL(drm_edid_to_speaker_allocation);
> >
> > +/**
> > + * drm_cea_sad_get_sample_rate - Extract the sample rate from
> > cea_sad
> > + * @sad: Pointer to the cea_sad struct
> > + *
> > + * Extracts the cea_sad frequency field and returns the sample
> > rate in Hz.
> > + *
> > + * Return: Sample rate in Hz or a negative errno if parsing
> > failed.
> > + */
> > +int drm_cea_sad_get_sample_rate(const struct cea_sad *sad)
> > +{
> > + switch (sad->freq) {
> > + case DRM_CEA_SAD_FREQ_32KHZ:
> > + return 32000;
> > + case DRM_CEA_SAD_FREQ_44KHZ:
> > + return 44100;
> > + case DRM_CEA_SAD_FREQ_48KHZ:
> > + return 48000;
> > + case DRM_CEA_SAD_FREQ_88KHZ:
> > + return 88200;
> > + case DRM_CEA_SAD_FREQ_96KHZ:
> > + return 96000;
> > + case DRM_CEA_SAD_FREQ_176KHZ:
> > + return 176400;
> > + case DRM_CEA_SAD_FREQ_192KHZ:
> > + return 192000;
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +EXPORT_SYMBOL(drm_cea_sad_get_sample_rate);
> > +
> > +static bool drm_cea_sad_is_pcm(const struct cea_sad *sad)
> > +{
> > + switch (sad->format) {
> > + case HDMI_AUDIO_CODING_TYPE_PCM:
> > + return true;
> > + default:
> > + return false;
> > + }
>
> Are you sure that you need this helper? That's used only in one
> function...
> ...if you really need this one, though, I don't think that using a
> switch
> is the best option here.
>
> Unless anyone is against that (please, reason?), I would be for doing
> it like:
>
> return sad->format == HDMI_AUDIO_CODING_TYPE_PCM;
>
> Everything else looks good to me (and working, too).
>
> Cheers,
> Angelo

Hello Angelo,

I think you are right,
in this case, we don't need this help function.
I will merge this function into
drm_cea_sad_get_uncompressed_word_length()

BRs,
Bo-Chen