Hello Jacopo,
Thank you for the patch.
On Tue, Jul 23, 2019 at 06:57:00PM +0200, Jacopo Mondi wrote:
> The R-Car LVDS encoder units support dual-link operations by splitting
> the pixel output between the primary encoder and the companion one.
s/the companion one/its companion/
>
> In order for the primary encoder to succesfully control the companion's
> operations this should not fail at probe time and register itself its
> associated drm bridge so that the primary one can find it.
This is hard to parse.
> Currently the companion encoder fails at probe time, causing the
> registration of the primary to fail preventing the whole DU unit to be
> registered correctly.
>
> Fixes: fa440d870358 ("drm: rcar-du: lvds: Add support for dual-link mode")
> Reported-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
>
> ---
> The "Fixes" tag refers to a patch currently part of the
> renesas-drivers-2019-07-09-v5.2 branch of Geert's renesas-drivers tree.
>
> drivers/gpu/drm/rcar-du/rcar_lvds.c | 31 +++++++++++++++++++++--------
> 1 file changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> index bada7ee98544..8b015ba95895 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> @@ -767,14 +767,29 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> of_node_put(remote_input);
> of_node_put(remote);
>
> - /*
> - * On D3/E3 the LVDS encoder provides a clock to the DU, which can be
> - * used for the DPAD output even when the LVDS output is not connected.
> - * Don't fail probe in that case as the DU will need the bridge to
> - * control the clock.
> - */
> - if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> - return ret == -ENODEV ? 0 : ret;
> + switch (ret) {
> + case -ENODEV:
> + /*
> + * On D3/E3 the LVDS encoder provides a clock to the DU, which
> + * can be used for the DPAD output even when the LVDS output is
> + * not connected. Don't fail probe in that case as the DU will
> + * need the bridge to control the clock.
> + */
> + if (lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)
> + ret = 0;
> + break;
> + case -ENXIO:
> + /*
> + * When the LVDS output is used in dual link mode, the
> + * companion encoder fails at
> + * 'rcar_lvds_parse_dt_companion()'. Don't fail probe in
> + * that case as the master encoder will need the companion's
> + * bridge to control its operations.
> + */
> + if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK)
> + ret = 0;
As -ENXIO can only be returned by rcar_lvds_parse_dt_companion(), and
rcar_lvds_parse_dt_companion() is only called when the
RCAR_LVDS_QUIRK_DUAL_LINK flag is set, this essentially means that you
always zero the error returned from rcar_lvds_parse_dt_companion(). This
is both complicated and too drastic as the second -ENXIO error case
shouldn't be ignored. It would be better and simpler to return 0 from
rcar_lvds_parse_dt_companion() when the renesas,companion property can't
be found.
> + break;
> + }
>
> return ret;
> }
--
Regards,
Laurent Pinchart
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