linux-kernel - Re: [PATCH v5 4/7] drm/bridge: dw-hdmi: Add API dw_hdmi_set_sample

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Message-ID: <CAA+D8APA85PhWVkW7c=d_qWF7L1ERxe7cS3Gg00SV-3TSyLwQw@mail.gmail.com>
Date: Tue, 23 Sep 2025 09:29:23 +0800
From: Shengjiu Wang <shengjiu.wang@...il.com>
To: Liu Ying <victor.liu@....com>
Cc: Maxime Ripard <mripard@...nel.org>, Luca Ceresoli <luca.ceresoli@...tlin.com>, 
	Shengjiu Wang <shengjiu.wang@....com>, andrzej.hajda@...el.com, neil.armstrong@...aro.org, 
	rfoss@...nel.org, Laurent.pinchart@...asonboard.com, jonas@...boo.se, 
	jernej.skrabec@...il.com, maarten.lankhorst@...ux.intel.com, 
	tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch, lumag@...nel.org, 
	dianders@...omium.org, cristian.ciocaltea@...labora.com, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de, 
	festevam@...il.com, imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	p.zabel@...gutronix.de, devicetree@...r.kernel.org, l.stach@...gutronix.de, 
	perex@...ex.cz, tiwai@...e.com, linux-sound@...r.kernel.org
Subject: Re: [PATCH v5 4/7] drm/bridge: dw-hdmi: Add API dw_hdmi_set_sample_iec958()
 for iec958 format

On Mon, Sep 22, 2025 at 11:01 AM Liu Ying <victor.liu@....com> wrote:
>
> On 09/10/2025, Shengjiu Wang wrote:
> > Hi
> >
> > On Tue, Sep 9, 2025 at 2:39 PM Maxime Ripard <mripard@...nel.org> wrote:
> >>
> >> Hi,
> >>
> >> On Wed, Sep 03, 2025 at 06:41:05PM +0800, Shengjiu Wang wrote:
> >>> On Tue, Sep 2, 2025 at 12:52 AM Luca Ceresoli <luca.ceresoli@...tlin.com> wrote:
> >>>>
> >>>> Hello Shengjiu,
> >>>>
> >>>> On Thu, 21 Aug 2025 15:31:28 +0800
> >>>> Shengjiu Wang <shengjiu.wang@....com> wrote:
> >>>>
> >>>>> Add API dw_hdmi_set_sample_iec958() for IEC958 format because audio device
> >>>>> driver needs IEC958 information to configure this specific setting.
> >>>>>
> >>>>> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> >>>>> Acked-by: Liu Ying <victor.liu@....com>
> >>>>
> >>>> [...]
> >>>>
> >>>>> +void dw_hdmi_set_sample_iec958(struct dw_hdmi *hdmi, unsigned int iec958)
> >>>>> +{
> >>>>> +     mutex_lock(&hdmi->audio_mutex);
> >>>>> +     hdmi->sample_iec958 = iec958;
> >>>>> +     mutex_unlock(&hdmi->audio_mutex);
> >>>>> +}
> >>>>
> >>>> Apologies for jumping in the discussion as late as in v5, but I noticed
> >>>> this patch and I was wondering whether this mutex_lock/unlock() is
> >>>> really needed, as you're copying an int.
> >>>
> >>> Thanks for your comments.
> >>>
> >>> Seems it is not necessary to add mutex here. I just follow the code as
> >>> other similar functions.  I will send a new version to update it.
> >>
> >> Let's not be smart about it. Next thing you know, someone will add
> >> another field in there that would absolutely require a mutex and now
> >> you're not race free anymore.
> >>
> >> Unless there's a real concern, the mutex must stay.
> >>
> >
> > Ok, thanks for comments.  Then Patch v6 need to be dropped.
>
> To properly track the changelog with patchwork, can you send v7 to add
> the mutex?

Yes, will send it.

Best regards

Shengjiu wang

>
> >
> > Is there any other comments for this Patch v5?
> > If no, can this series be accepted?
> >
> > Best regards
> > Shengjiu Wang
>
>
> --
> Regards,
> Liu Ying