On Thu, 2020-07-02 at 17:40 +0300, Ville Syrjälä wrote:
> On Tue, Jun 30, 2020 at 11:42:36PM +0000, Souza, Jose wrote:
> > On Wed, 2020-05-27 at 16:03 +0300, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > >
> > > Apparently EDIDs with multiple DispID ext blocks is a thing, so prepare
> > > for iterating through multiple ext blocks of the same type by
> > > passing the starting ext block index to drm_find_edid_extension(). Well
> > > also have drm_find_edid_extension() update the index to point to the
> > > next ext block on success. Thus we should be able to call
> > > drm_find_edid_extension() in loop.
> > >
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/drm_edid.c | 30 +++++++++++++++++++++---------
> > > 1 file changed, 21 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > > index d8372d63851b..f2531d51dfa2 100644
> > > --- a/drivers/gpu/drm/drm_edid.c
> > > +++ b/drivers/gpu/drm/drm_edid.c
> > > @@ -3188,7 +3188,8 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
> > > /*
> > > * Search EDID for CEA extension block.
> > > */
> > > -static u8 *drm_find_edid_extension(const struct edid *edid, int ext_id)
> > > +static u8 *drm_find_edid_extension(const struct edid *edid,
> > > + int ext_id, int *ext_index)
> > > {
> > > u8 *edid_ext = NULL;
> > > int i;
> > > @@ -3198,23 +3199,26 @@ static u8 *drm_find_edid_extension(const struct edid *edid, int ext_id)
> > > return NULL;
> > >
> > > /* Find CEA extension */
> > > - for (i = 0; i < edid->extensions; i++) {
> > > + for (i = *ext_index; i < edid->extensions; i++) {
> > > edid_ext = (u8 *)edid + EDID_LENGTH * (i + 1);
> > > if (edid_ext[0] == ext_id)
> > > break;
> > > }
> > >
> > > - if (i == edid->extensions)
> > > + if (i >= edid->extensions)
> > > return NULL;
> > >
> > > + *ext_index = i + 1;
> > > +
> > > return edid_ext;
> > > }
> > >
> >
> > I would add something like drm_find_edid_n_extension() with the implementation above and then implement drm_find_edid_extension() calling
> > drm_find_edid_n_extension() but it is just one caller that is not using ext_index so LGTM.
> >
> > >
> > > static u8 *drm_find_displayid_extension(const struct edid *edid,
> > > - int *length, int *idx)
> > > + int *length, int *idx,
> > > + int *ext_index)
> > > {
> > > - u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT);
> > > + u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT, ext_index);
> > > struct displayid_hdr *base;
> > > int ret;
> > >
> > > @@ -3241,14 +3245,18 @@ static u8 *drm_find_cea_extension(const struct edid *edid)
> > > struct displayid_block *block;
> > > u8 *cea;
> > > u8 *displayid;
> > > + int ext_index;
> > >
> > > /* Look for a top level CEA extension block */
> > > - cea = drm_find_edid_extension(edid, CEA_EXT);
> > > + ext_index = 0;
> >
> > In 2 places ext_index is initialized in the variable declaration and in 2 other places is not, all of it could be done in the declaration
>
> No, in this case we need to reset it back to 0 when the start looking
> for the DispID ext block (as opposed to the CEA ext block). So I figured
> it's cleaner if both initialize it to 0 the same way. All the other
> places need just the one initialization.
>
> Eventually I think I'd like some kind of for_each_ext_block() to make
> this stuff less crap...
Okay makes sense.
Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
>
> > or if you
> > really want to leave the context close to the users, initialize it in the "for (;;)" in the next patch.
> >
> > With the change above:
> >
> > Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
> >
> > > + cea = drm_find_edid_extension(edid, CEA_EXT, &ext_index);
> > > if (cea)
> > > return cea;
> > >
> > > /* CEA blocks can also be found embedded in a DisplayID block */
> > > - displayid = drm_find_displayid_extension(edid, &length, &idx);
> > > + ext_index = 0;
> > > + displayid = drm_find_displayid_extension(edid, &length, &idx,
> > > + &ext_index);
> > > if (!displayid)
> > > return NULL;
> > >
> > > @@ -5195,8 +5203,10 @@ static int add_displayid_detailed_modes(struct drm_connector *connector,
> > > int length, idx;
> > > struct displayid_block *block;
> > > int num_modes = 0;
> > > + int ext_index = 0;
> > >
> > > - displayid = drm_find_displayid_extension(edid, &length, &idx);
> > > + displayid = drm_find_displayid_extension(edid, &length, &idx,
> > > + &ext_index);
> > > if (!displayid)
> > > return 0;
> > >
> > > @@ -5870,11 +5880,13 @@ void drm_update_tile_info(struct drm_connector *connector,
> > > const struct edid *edid)
> > > {
> > > const void *displayid = NULL;
> > > + int ext_index = 0;
> > > int length, idx;
> > > int ret;
> > >
> > > connector->has_tile = false;
> > > - displayid = drm_find_displayid_extension(edid, &length, &idx);
> > > + displayid = drm_find_displayid_extension(edid, &length, &idx,
> > > + &ext_index);
> > > if (!displayid) {
> > > /* drop reference to any tile group we had */
> > > goto out_drop_ref;
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