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SubjectRe: [PATCH v5 4/6] drm: rcar-du: lvds: Allow for even and odd pixels swap
Hi Fabrizio,

Thank you for the patch.

On Mon, Dec 16, 2019 at 08:12:32PM +0000, Fabrizio Castro wrote:
> DT properties dual-lvds-even-pixels and dual-lvds-odd-pixels
> can be used to work out if the driver needs to swap even
> and odd pixels around.
>
> This patch makes use of the return value from function
> drm_of_lvds_get_dual_link_pixel_order to determine if we
> need to swap odd and even pixels around for things to work
> properly.
>
> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
>
> ---
> v4->v5:
> * Addressed comments from Laurent's review
>
> v3->v4:
> * New patch extracted from patch:
> "drm: rcar-du: lvds: Add dual-LVDS panels support"
> ---
> drivers/gpu/drm/rcar-du/rcar_lvds.c | 67 +++++++++++++++++++++++++++++--------
> 1 file changed, 53 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> index 3eb208e..c6a38c3 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> @@ -37,6 +37,12 @@ enum rcar_lvds_mode {
> RCAR_LVDS_MODE_VESA = 4,
> };
>
> +enum rcar_lvds_link_type {
> + RCAR_LVDS_SINGLE_LINK = 0,
> + RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS = 1,
> + RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS = 2,
> +};
> +
> #define RCAR_LVDS_QUIRK_LANES BIT(0) /* LVDS lanes 1 and 3 inverted */
> #define RCAR_LVDS_QUIRK_GEN3_LVEN BIT(1) /* LVEN bit needs to be set on R8A77970/R8A7799x */
> #define RCAR_LVDS_QUIRK_PWD BIT(2) /* PWD bit available (all of Gen3 but E3) */
> @@ -67,7 +73,7 @@ struct rcar_lvds {
> } clocks;
>
> struct drm_bridge *companion;
> - bool dual_link;
> + enum rcar_lvds_link_type dual_link;

Do you think we should rename this to link_type (and test for
lvds->link_type != RCAR_LVDS_SINGLE_LINK) instead of lvds->dual_link) ?
Apart from that,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> };
>
> #define bridge_to_rcar_lvds(b) \
> @@ -484,12 +490,31 @@ static void rcar_lvds_atomic_enable(struct drm_bridge *bridge,
> rcar_lvds_write(lvds, LVDCHCR, lvdhcr);
>
> if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK) {
> - /*
> - * Configure vertical stripe based on the mode of operation of
> - * the connected device.
> - */
> - rcar_lvds_write(lvds, LVDSTRIPE,
> - lvds->dual_link ? LVDSTRIPE_ST_ON : 0);
> + u32 lvdstripe = 0;
> +
> + if (lvds->dual_link) {
> + /*
> + * By default we generate even pixels from the primary
> + * encoder and odd pixels from the companion encoder.
> + * Swap pixels around if the sink requires odd pixels
> + * from the primary encoder and even pixels from the
> + * companion encoder.
> + */
> + bool swap_pixels = lvds->dual_link ==
> + RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS;
> +
> + /*
> + * Configure vertical stripe since we are dealing with
> + * an LVDS dual-link connection.
> + *
> + * ST_SWAP is reserved for the companion encoder, only
> + * set it in the primary encoder.
> + */
> + lvdstripe = LVDSTRIPE_ST_ON
> + | (lvds->companion && swap_pixels ?
> + LVDSTRIPE_ST_SWAP : 0);
> + }
> + rcar_lvds_write(lvds, LVDSTRIPE, lvdstripe);
> }
>
> /*
> @@ -716,15 +741,26 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
> of_node_put(port0);
> of_node_put(port1);
>
> - if (dual_link >= DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS)
> - lvds->dual_link = true;
> - else if (lvds->next_bridge && lvds->next_bridge->timings)
> + switch (dual_link) {
> + case DRM_LVDS_DUAL_LINK_ODD_EVEN_PIXELS:
> + lvds->dual_link = RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS;
> + break;
> + case DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS:
> + lvds->dual_link = RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS;
> + break;
> + default:
> /*
> * Early dual-link bridge specific implementations populate the
> - * timings field of drm_bridge, read the dual_link flag off the
> - * bridge directly for backward compatibility.
> + * timings field of drm_bridge. If the flag is set, we assume
> + * that we are expected to generate even pixels from the primary
> + * encoder, and odd pixels from the companion encoder.
> */
> - lvds->dual_link = lvds->next_bridge->timings->dual_link;
> + if (lvds->next_bridge && lvds->next_bridge->timings &&
> + lvds->next_bridge->timings->dual_link)
> + lvds->dual_link = RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS;
> + else
> + lvds->dual_link = RCAR_LVDS_SINGLE_LINK;
> + }
>
> if (!lvds->dual_link) {
> dev_dbg(dev, "Single-link configuration detected\n");
> @@ -741,6 +777,9 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
> "Dual-link configuration detected (companion encoder %pOF)\n",
> companion);
>
> + if (lvds->dual_link == RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS)
> + dev_dbg(dev, "Data swapping required\n");
> +
> /*
> * FIXME: We should not be messing with the companion encoder private
> * data from the primary encoder, we should rather let the companion
> @@ -751,7 +790,7 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
> * for the time being.
> */
> companion_lvds = bridge_to_rcar_lvds(lvds->companion);
> - companion_lvds->dual_link = true;
> + companion_lvds->dual_link = lvds->dual_link;
>
> done:
> of_node_put(companion);

--
Regards,

Laurent Pinchart

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