Re: [PATCH 2/3] drm/rockchip: Add optional support for CRTC gamma LUT

Ilia Mirkin
2019-06-18T21:47:36Z

On Tue, Jun 18, 2019 at 5:43 PM Ezequiel Garcia <ezequiel@collabora.com> wrote:
>
> Add an optional CRTC gamma LUT support, and enable it on RK3288.
> This is currently enabled via a separate address resource,
> which needs to be specified in the devicetree.
>
> The address resource is required because on some SoCs, such as
> RK3288, the LUT address is after the MMU address, and the latter
> is supported by a different driver. This prevents the DRM driver
> from requesting an entire register space.
>
> The current implementation works for RGB 10-bit tables, as that
> is what seems to work on RK3288.
>
> Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
> ---
> Changes from RFC:
> * Request (an optional) address resource for the LUT.
> * Drop support for RK3399, which doesn't seem to work
> out of the box and needs more research.
> * Support pass-thru setting when GAMMA_LUT is NULL.
> * Add a check for the gamma size, as suggested by Ilia.
> * Move gamma setting to atomic_commit_tail, as pointed
> out by Jacopo/Laurent, is the correct way.
> ---
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index 12ed5265a90b..5b6edbe2673f 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +static void vop_crtc_gamma_set(struct vop *vop, struct drm_crtc *crtc,
> + struct drm_crtc_state *old_state)
> +{
> + int idle, ret, i;
> +
> + spin_lock(&vop->reg_lock);
> + VOP_REG_SET(vop, common, dsp_lut_en, 0);
> + vop_cfg_done(vop);
> + spin_unlock(&vop->reg_lock);
> +
> + ret = readx_poll_timeout(vop_dsp_lut_is_enable, vop,
> + idle, !idle, 5, 30 * 1000);
> + if (ret)
> + return;
> +
> + spin_lock(&vop->reg_lock);
> +
> + if (crtc->state->gamma_lut) {
> + if (!old_state->gamma_lut || (crtc->state->gamma_lut->base.id !=
> + old_state->gamma_lut->base.id))
> + vop_crtc_write_gamma_lut(vop, crtc);
> + } else {
> + for (i = 0; i < crtc->gamma_size; i++) {
> + u32 word;
> +
> + word = (i << 20) | (i << 10) | i;
> + writel(word, vop->lut_regs + i * 4);
> + }

Note - I'm not in any way familiar with the hardware, so take with a
grain of salt --

Could you just leave dsp_lut_en turned off in this case?

Cheers,

-ilia

> + }
> +
> + VOP_REG_SET(vop, common, dsp_lut_en, 1);
> + vop_cfg_done(vop);
> + spin_unlock(&vop->reg_lock);
> +}