> On September 14, 2018 at 11:10 AM Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> wrote:
>
>
> On selected SoCs, the DU can use the clock output by the LVDS encoder
> PLL as its input dot clock. This feature is optional, but on the D3 and
> E3 SoC it is often the only way to obtain a precise dot clock frequency,
> as the other available clocks (CPG-generated clock and external clock)
> usually have fixed rates.
>
> Add a DU model information field to describe which DU channels can use
> the LVDS PLL output clock as their input clock, and configure clock
> routing accordingly.
>
> This feature is available on H2, M2-W, M2-N, D3 and E3 SoCs, with D3 and
> E3 being the primary targets. It is left disabled in this commit, and
> will be enabled per-SoC after careful testing.
>
> At the hardware level, clock routing is configured at runtime in two
> steps, first selecting an internal dot clock between the LVDS PLL clock
> and the external DOTCLKIN clock, and then selecting between the internal
> dot clock and the CPG-generated clock. The first part requires stopping
> the whole DU group in order for the change to take effect, thus causing
> flickering on the screen. For this reason we currently hardcode the
> clock source to the LVDS PLL clock if available, and allow flicker-free
> selection of the external DOTCLKIN clock or CPG-generated clock
> otherwise. A more dynamic clock selection process can be implemented
> later if the need arises.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> Tested-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 8 +++++
> drivers/gpu/drm/rcar-du/rcar_du_drv.h | 2 ++
> drivers/gpu/drm/rcar-du/rcar_du_group.c | 64 +++++++++++++++++++++++++--------
> 3 files changed, 59 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index c89751c26f9c..2f8776c1ec8f 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -261,6 +261,14 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc)
> rcar_du_group_write(rcrtc->group, DPLLCR, dpllcr);
>
> escr = ESCR_DCLKSEL_DCLKIN | div;
> + } else if (rcdu->info->lvds_clk_mask & BIT(rcrtc->index)) {
> + /*
> + * Use the LVDS PLL output as the dot clock when outputting to
> + * the LVDS encoder on an SoC that supports this clock routing
> + * option. We use the clock directly in that case, without any
> + * additional divider.
> + */
> + escr = ESCR_DCLKSEL_DCLKIN;
> } else {
> struct du_clk_params params = { .diff = (unsigned long)-1 };
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> index fef9ea5c22f3..ebba9aefba6a 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> @@ -53,6 +53,7 @@ struct rcar_du_output_routing {
> * @routes: array of CRTC to output routes, indexed by output (RCAR_DU_OUTPUT_*)
> * @num_lvds: number of internal LVDS encoders
> * @dpll_mask: bit mask of DU channels equipped with a DPLL
> + * @lvds_clk_mask: bitmask of channels that can use the LVDS clock as dot clock
> */
> struct rcar_du_device_info {
> unsigned int gen;
> @@ -62,6 +63,7 @@ struct rcar_du_device_info {
> struct rcar_du_output_routing routes[RCAR_DU_OUTPUT_MAX];
> unsigned int num_lvds;
> unsigned int dpll_mask;
> + unsigned int lvds_clk_mask;
> };
>
> #define RCAR_DU_MAX_CRTCS 4
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_group.c b/drivers/gpu/drm/rcar-du/rcar_du_group.c
> index ef2c177afb6d..4c62841eff2f 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_group.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_group.c
> @@ -89,6 +89,54 @@ static void rcar_du_group_setup_defr8(struct rcar_du_group *rgrp)
> rcar_du_group_write(rgrp, DEFR8, defr8);
> }
>
> +static void rcar_du_group_setup_didsr(struct rcar_du_group *rgrp)
> +{
> + struct rcar_du_device *rcdu = rgrp->dev;
> + struct rcar_du_crtc *rcrtc;
> + unsigned int num_crtcs = 0;
> + unsigned int i;
> + u32 didsr;
> +
> + /*
> + * Configure input dot clock routing with a hardcoded configuration. If
> + * the DU channel can use the LVDS encoder output clock as the dot
> + * clock, do so. Otherwise route DU_DOTCLKINn signal to DUn.
> + *
> + * Each channel can then select between the dot clock configured here
> + * and the clock provided by the CPG through the ESCR register.
> + */
> + if (rcdu->info->gen < 3 && rgrp->index == 0) {
> + /*
> + * On Gen2 a single register in the first group controls dot
> + * clock selection for all channels.
> + */
> + rcrtc = rcdu->crtcs;
> + num_crtcs = rcdu->num_crtcs;
> + } else if (rcdu->info->gen == 3 && rgrp->num_crtcs > 1) {
> + /*
> + * On Gen3 dot clocks are setup through per-group registers,
> + * only available when the group has two channels.
> + */
> + rcrtc = &rcdu->crtcs[rgrp->index * 2];
> + num_crtcs = rgrp->num_crtcs;
> + }
> +
> + if (!num_crtcs)
> + return;
> +
> + didsr = DIDSR_CODE;
> + for (i = 0; i < num_crtcs; ++i, ++rcrtc) {
> + if (rcdu->info->lvds_clk_mask & BIT(rcrtc->index))
> + didsr |= DIDSR_LCDS_LVDS0(i)
> + | DIDSR_PDCS_CLK(i, 0);
> + else
> + didsr |= DIDSR_LCDS_DCLKIN(i)
> + | DIDSR_PDCS_CLK(i, 0);
> + }
> +
> + rcar_du_group_write(rgrp, DIDSR, didsr);
> +}
> +
> static void rcar_du_group_setup(struct rcar_du_group *rgrp)
> {
> struct rcar_du_device *rcdu = rgrp->dev;
> @@ -106,21 +154,7 @@ static void rcar_du_group_setup(struct rcar_du_group *rgrp)
>
> if (rcar_du_has(rgrp->dev, RCAR_DU_FEATURE_EXT_CTRL_REGS)) {
> rcar_du_group_setup_defr8(rgrp);
> -
> - /*
> - * Configure input dot clock routing. We currently hardcode the
> - * configuration to routing DOTCLKINn to DUn. Register fields
> - * depend on the DU generation, but the resulting value is 0 in
> - * all cases.
> - *
> - * On Gen2 a single register in the first group controls dot
> - * clock selection for all channels, while on Gen3 dot clocks
> - * are setup through per-group registers, only available when
> - * the group has two channels.
> - */
> - if ((rcdu->info->gen < 3 && rgrp->index == 0) ||
> - (rcdu->info->gen == 3 && rgrp->num_crtcs > 1))
> - rcar_du_group_write(rgrp, DIDSR, DIDSR_CODE);
> + rcar_du_group_setup_didsr(rgrp);
> }
>
> if (rcdu->info->gen >= 3)
> --
Reviewed-by: Ulrich Hecht <uli+renesas@xxxxxxxx>
CU
Uli
