linux-kernel - Re: [PATCH] drm/edid: Dump the EDID when drm_edid_get_panel

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Date:   Fri, 21 Oct 2022 14:18:16 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Douglas Anderson <dianders@...omium.org>,
        <dri-devel@...ts.freedesktop.org>
CC:     Kuogee Hsieh <quic_khsieh@...cinc.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/edid: Dump the EDID when drm_edid_get_panel_id() has
 an error

Hi Doug

On 10/21/2022 1:07 PM, Douglas Anderson wrote:
> If we fail to get a valid panel ID in drm_edid_get_panel_id() we'd
> like to see the EDID that was read so we have a chance of
> understanding what's wrong. There's already a function for that, so
> let's call it in the error case.
> 
> NOTE: edid_block_read() has a retry loop in it, so actually we'll only
> print the block read back from the final attempt. This still seems
> better than nothing.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Instead of checkinf for edid_block_status_valid() on the base_block, do 
you want to use drm_edid_block_valid() instead?

That way you get the edid_block_dump() for free if it was invalid.

> ---
> 
>   drivers/gpu/drm/drm_edid.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 47465b9765f1..d63e26ec88b1 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2721,6 +2721,8 @@ u32 drm_edid_get_panel_id(struct i2c_adapter *adapter)
>   
>   	if (edid_block_status_valid(status, edid_block_tag(base_block)))
>   		panel_id = edid_extract_panel_id(base_block);
> +	else
> +		edid_block_dump(KERN_NOTICE, base_block, 0);
>   
>   	kfree(base_block);
>