linux-kernel - Re: [PATCH v4] drm/bridge: adv7511_audio: Update Audio InfoFrame properly

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Message-ID: <hahl4w56e23duuehcvqeaq7orrm77o7cobwpbgl5xh56fynefc@lapt2cdjuhai>
Date: Fri, 20 Dec 2024 03:30:50 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Stefan Ekenberg <stefan.ekenberg@...s.com>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, kernel@...s.com, Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v4] drm/bridge: adv7511_audio: Update Audio InfoFrame
 properly

On Tue, Nov 19, 2024 at 08:40:29AM +0100, Stefan Ekenberg wrote:
> AUDIO_UPDATE bit (Bit 5 of MAIN register 0x4A) needs to be set to 1
> while updating Audio InfoFrame information and then set to 0 when done.
> Otherwise partially updated Audio InfoFrames could be sent out. Two
> cases where this rule were not followed are fixed:
>  - In adv7511_hdmi_hw_params() make sure AUDIO_UPDATE bit is updated
>    before/after setting ADV7511_REG_AUDIO_INFOFRAME.
>  - In audio_startup() use the correct register for clearing
>    AUDIO_UPDATE bit.
> 
> The problem with corrupted audio infoframes were discovered by letting
> a HDMI logic analyser check the output of ADV7535.
> 
> Note that this patchs replaces writing REG_GC(1) with
> REG_INFOFRAME_UPDATE. Bit 5 of REG_GC(1) is positioned within field
> GC_PP[3:0] and that field doesn't control audio infoframe and is read-
> only. My conclusion therefore was that the author if this code meant to
> clear bit 5 of REG_INFOFRAME_UPDATE from the very beginning.
> 
> Tested-by: Biju Das <biju.das.jz@...renesas.com>
> Fixes: 53c515befe28 ("drm/bridge: adv7511: Add Audio support")
> Signed-off-by: Stefan Ekenberg <stefan.ekenberg@...s.com>
> ---
> Changes in v4:
> - Add Tested-by tag
> - Link to v3: https://lore.kernel.org/r/20241118-adv7511-audio-info-frame-v3-1-31edd9931856@axis.com
> 
> Changes in v3:
> - Extend commit message and explain replacement of REG_GC(1)
> - Link to v2: https://lore.kernel.org/r/20241115-adv7511-audio-info-frame-v2-1-ca4793ef3a91@axis.com
> 
> Changes in v2:
> - Add Fixes tag
> - Link to v1: https://lore.kernel.org/r/20241113-adv7511-audio-info-frame-v1-1-49b368b995a5@axis.com
> ---
>  drivers/gpu/drm/bridge/adv7511/adv7511_audio.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry