linux-kernel - Re: [PATCH v5 1/6] drm_edid: Add a function to get EDID base block

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

Hi,

On Wed, Mar 6, 2024 at 12:04 PM Hsin-Yi Wang <hsinyi@...omium.org> wrote:
>
> @@ -2764,58 +2764,71 @@ static u32 edid_extract_panel_id(const struct edid *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 (assuming
> + * This function uses the first block of the EDID of a panel and (assuming
>   * 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 panel.
> + *         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@...omium.org>