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From: Doug Anderson <dianders@chromium.org>
Date: Wed, 6 Mar 2024 15:29:20 -0800
Message-ID: <CAD=FV=XcMRLvSU+_QrNMSOo4JH0hPmA-F3HFjOBj=QwHHQy_mA@mail.gmail.com>
Subject: Re: [PATCH v5 1/6] drm_edid: Add a function to get EDID base block
To: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>, 
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>, Neil Armstrong <neil.armstrong@linaro.org>, 
	Jessica Zhang <quic_jesszhan@quicinc.com>, Sam Ravnborg <sam@ravnborg.org>, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, 
	Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
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Hi,

On Wed, Mar 6, 2024 at 12:04=E2=80=AFPM Hsin-Yi Wang <hsinyi@chromium.org> =
wrote:
>
> @@ -2764,58 +2764,71 @@ static u32 edid_extract_panel_id(const struct edi=
d *edid)
>  }
>
>  /**
> - * drm_edid_get_panel_id - Get a panel's ID through DDC
> - * @adapter: I2C adapter to use for DDC
> + * drm_edid_get_panel_id - Get a panel's ID from EDID
> + * @drm_edid: EDID that contains panel ID.
>   *
> - * This function reads the first block of the EDID of a panel and (assum=
ing
> + * This function uses the first block of the EDID of a panel and (assumi=
ng
>   * that the EDID is valid) extracts the ID out of it. The ID is a 32-bit=
 value
>   * (16 bits of manufacturer ID and 16 bits of per-manufacturer ID) that'=
s
>   * supposed to be different for each different modem of panel.
>   *
> + * Return: A 32-bit ID that should be different for each make/model of p=
anel.
> + *         See the functions drm_edid_encode_panel_id() and
> + *         drm_edid_decode_panel_id() for some details on the structure =
of this
> + *         ID.
> + */
> +u32 drm_edid_get_panel_id(const struct drm_edid *drm_edid)
> +{

I'd leave it up to Jani, but I'd wonder whether we need to confirm
drm_edid->size here is at least as big as the base block. In other
words: is there ever any chance that someone would have allocated a
struct drm_edid but not actually read a full base block into it?

In any case:

Reviewed-by: Douglas Anderson <dianders@chromium.org>