Re: [PATCH] drm/edid: Dump the EDID when drm_edid_get_panel_id() has an error

[Abhinav Kumar]

Hi Doug

On 10/24/2022 1:28 PM, Doug Anderson wrote:
> Hi,
>
> On Fri, Oct 21, 2022 at 2:18 PM Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> > 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@xxxxxxxxxxxx>
> >
> > 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.
>
> I can... ...but it feels a bit awkward and maybe not quite how the
> functions were intended to work together?
>
> One thing I notice is that if I call drm_edid_block_valid() I'm doing
> a bunch of duplicate work that already happened in edid_block_read(),
> which already calls edid_block_check() and handles fixing headers. I
> guess also if I call drm_edid_block_valid() then I should ignore the
> "status" return value of edid_block_read() because we don't need to
> pass it anywhere (because the work is re-done in
> drm_edid_block_valid()).
>
> So I guess I'm happy to do a v2 like that if everyone likes it better,
> but to me it feels a little weird.
>
> -Doug

Alright, agreed. There is some duplication of code happening if we use 
drm_edid_block_valid(). I had suggested that because it has inherent 
support for dumping the bad EDID.

In that case, this change LGTM, because in principle you are doing the 
same thing as _drm_do_get_edid() (with the only difference being here we 
read only the base block as opposed to the full EDID there).

Hence,

Reviewed-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>