Re: [PATCH v15 03/11] drm/edid: Add cea_sad helpers for freq/length

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Rex-BC Chen <rex-bc.chen@mediatek.com>,
	chunkuang.hu@kernel.org, p.zabel@pengutronix.de, daniel@ffwll.ch,
	robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
	mripard@kernel.org, tzimmermann@suse.de, matthias.bgg@gmail.com,
	deller@gmx.de, airlied@linux.ie
Cc: devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org,
	granquet@baylibre.com, jitao.shi@mediatek.com,
	liangxu.xu@mediatek.com, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, msp@baylibre.com,
	Project_Global_Chrome_Upstream_Group@mediatek.com,
	linux-mediatek@lists.infradead.org, wenst@chromium.org,
	linux-arm-kernel@lists.infradead.org,
	angelogioacchino.delregno@collabora.com
Subject: Re: [PATCH v15 03/11] drm/edid: Add cea_sad helpers for freq/length
Date: Fri, 05 Aug 2022 10:54:26 +0300	[thread overview]
Message-ID: <87mtcjnn0t.fsf@intel.com> (raw)
In-Reply-To: <ad9207524145fdc8338894be70228820f40a49d8.camel@mediatek.com>

On Fri, 05 Aug 2022, Rex-BC Chen <rex-bc.chen@mediatek.com> wrote:
> On Tue, 2022-08-02 at 17:11 +0300, Jani Nikula wrote:
>> On Wed, 27 Jul 2022, Bo-Chen Chen <rex-bc.chen@mediatek.com> wrote:
>> > 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.
>> 
>> I think we should stop adding a plethora of functions that deal with
>> sads like this.
>> 
>> There should probably be *one* struct that contains all the details
>> you
>> and everyone need extracted. There should be *one* function that
>> fills
>> in all the details. The struct should be placed in
>> connector->display_info, and the function should be called *once*
>> from
>> update_display_info().
>> 
>> Ideally, the function shouldn't even be exposed from drm_edid.c, but
>> if
>> you still need to deal with situations where you don't call connector
>> update, maybe it needs to be exposed.
>> 
>> BR,
>> Jani.
>> 
>> 
>
> Hello Jani,
>
> Thanks for your review.
> After checking our patches, we found we will not use these two function
> because we remove them in patch [11/11] drm/mediatek: Use cached audio
> config when changing resolution.
>
> I will drop [02/11] and [03/11].
>
> Thanks!

Thank you too! :)

BR,
Jani.

>
> BRs,
> Bo-Chen
>
>> > 
>> > 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 | 63
>> > ++++++++++++++++++++++++++++++++++++++
>> >  include/drm/drm_edid.h     | 14 +++++++++
>> >  2 files changed, 77 insertions(+)
>> > 
>> > diff --git a/drivers/gpu/drm/drm_edid.c
>> > b/drivers/gpu/drm/drm_edid.c
>> > index bc43e1b32092..2a6f92da5ff3 100644
>> > --- a/drivers/gpu/drm/drm_edid.c
>> > +++ b/drivers/gpu/drm/drm_edid.c
>> > @@ -4916,6 +4916,69 @@ 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);
>> > +
>> > +/**
>> > + * drm_cea_sad_get_uncompressed_word_length - Extract word length
>> > + * @sad: Pointer to the cea_sad struct
>> > + *
>> > + * Extracts the cea_sad byte2 field and returns the word length
>> > for an
>> > + * uncompressed stream.
>> > + *
>> > + * Note: This function may only be called for uncompressed audio.
>> > + *
>> > + * Return: Word length in bits or a negative errno if parsing
>> > failed.
>> > + */
>> > +int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad
>> > *sad)
>> > +{
>> > +	if (sad->format != HDMI_AUDIO_CODING_TYPE_PCM) {
>> > +		DRM_WARN("Unable to get the uncompressed word length
>> > for format: %u\n",
>> > +			 sad->format);
>> > +		return -EINVAL;
>> > +	}
>> > +
>> > +	switch (sad->byte2) {
>> > +	case DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT:
>> > +		return 16;
>> > +	case DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT:
>> > +		return 20;
>> > +	case DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT:
>> > +		return 24;
>> > +	default:
>> > +		return -EINVAL;
>> > +	}
>> > +}
>> > +EXPORT_SYMBOL(drm_cea_sad_get_uncompressed_word_length);
>> > +
>> >  /**
>> >   * drm_av_sync_delay - compute the HDMI/DP sink audio-video sync
>> > delay
>> >   * @connector: connector associated with the HDMI/DP sink
>> > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>> > index c2c43a4af681..779b710aed40 100644
>> > --- a/include/drm/drm_edid.h
>> > +++ b/include/drm/drm_edid.h
>> > @@ -373,6 +373,18 @@ struct cea_sad {
>> >  	u8 byte2;
>> >  };
>> >  
>> > +#define DRM_CEA_SAD_FREQ_32KHZ  BIT(0)
>> > +#define DRM_CEA_SAD_FREQ_44KHZ  BIT(1)
>> > +#define DRM_CEA_SAD_FREQ_48KHZ  BIT(2)
>> > +#define DRM_CEA_SAD_FREQ_88KHZ  BIT(3)
>> > +#define DRM_CEA_SAD_FREQ_96KHZ  BIT(4)
>> > +#define DRM_CEA_SAD_FREQ_176KHZ BIT(5)
>> > +#define DRM_CEA_SAD_FREQ_192KHZ BIT(6)
>> > +
>> > +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT BIT(0)
>> > +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT BIT(1)
>> > +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT BIT(2)
>> > +
>> >  struct drm_encoder;
>> >  struct drm_connector;
>> >  struct drm_connector_state;
>> > @@ -380,6 +392,8 @@ struct drm_display_mode;
>> >  
>> >  int drm_edid_to_sad(const struct edid *edid, struct cea_sad
>> > **sads);
>> >  int drm_edid_to_speaker_allocation(const struct edid *edid, u8
>> > **sadb);
>> > +int drm_cea_sad_get_sample_rate(const struct cea_sad *sad);
>> > +int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad
>> > *sad);
>> >  int drm_av_sync_delay(struct drm_connector *connector,
>> >  		      const struct drm_display_mode *mode);
>> 
>> 
>

-- 
Jani Nikula, Intel Open Source Graphics Center