Re: [PATCH 1/3] drm/rockchip: lvds: add rk3568 support

From: Sascha Hauer
Date: Fri Jan 20 2023 - 04:17:33 EST


On Thu, Jan 19, 2023 at 09:48:03PM +0300, Alibek Omarov wrote:
> One of the ports of RK3568 can be configured as LVDS, re-using the DSI DPHY
>
> Signed-off-by: Alibek Omarov <a1ba.omarov@xxxxxxxxx>
> ---
> drivers/gpu/drm/rockchip/rockchip_lvds.c | 144 +++++++++++++++++++++--
> drivers/gpu/drm/rockchip/rockchip_lvds.h | 10 ++
> 2 files changed, 147 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
> index 68f6ebb33460..83c60240af85 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
> @@ -433,6 +433,90 @@ static void px30_lvds_encoder_disable(struct drm_encoder *encoder)
> drm_panel_unprepare(lvds->panel);
> }
>
> +static int rk3568_lvds_poweron(struct rockchip_lvds *lvds)
> +{
> + int ret;
> +
> + ret = clk_enable(lvds->pclk);
> + if (ret < 0) {
> + DRM_DEV_ERROR(lvds->dev, "failed to enable lvds pclk %d\n", ret);
> + return ret;
> + }
> +
> + ret = pm_runtime_get_sync(lvds->dev);
> + if (ret < 0) {
> + DRM_DEV_ERROR(lvds->dev, "failed to get pm runtime: %d\n", ret);
> + clk_disable(lvds->pclk);
> + return ret;
> + }
> +
> + /* Enable LVDS mode */
> + return regmap_update_bits(lvds->grf, RK3568_GRF_VO_CON2,
> + RK3568_LVDS0_MODE_EN(1),
> + RK3568_LVDS0_MODE_EN(1));

Isn't this the same as:

regmap_write(lvds->grf, RK3568_GRF_VO_CON2, RK3568_LVDS0_MODE_EN(1));

Unless I am missing something I find a plain regmap_write() easier to
read.

> +}
> +
> +static void rk3568_lvds_poweroff(struct rockchip_lvds *lvds)
> +{
> + regmap_update_bits(lvds->grf, RK3568_GRF_VO_CON2,
> + RK3568_LVDS0_MODE_EN(1) | RK3568_LVDS0_P2S_EN(1),
> + RK3568_LVDS0_MODE_EN(0) | RK3568_LVDS0_P2S_EN(0));

Same here:

regmap_write(lvds->grf, RK3568_GRF_VO_CON2,
RK3568_LVDS0_MODE_EN(0) | RK3568_LVDS0_P2S_EN(0));

What about the RK3568_LVDS0_P2S_EN bit? This is set in probe() and
cleared here. For symmetry reasons shouldn't it be set in
rk3568_lvds_poweron() instead?

> +
> + pm_runtime_put(lvds->dev);
> + clk_disable(lvds->pclk);
> +}
> +
> +static int rk3568_lvds_grf_config(struct drm_encoder *encoder,
> + struct drm_display_mode *mode)
> +{
> + struct rockchip_lvds *lvds = encoder_to_lvds(encoder);
> +
> + if (lvds->output != DISPLAY_OUTPUT_LVDS) {
> + DRM_DEV_ERROR(lvds->dev, "Unsupported display output %d\n",
> + lvds->output);
> + return -EINVAL;
> + }
> +
> + /* Set format */
> + return regmap_update_bits(lvds->grf, RK3568_GRF_VO_CON0,
> + RK3568_LVDS0_SELECT(3),
> + RK3568_LVDS0_SELECT(lvds->format));

It seems lvds->format does not match what the register expects. We
have:

#define LVDS_VESA_24 0
#define LVDS_JEIDA_24 1
#define LVDS_VESA_18 2
#define LVDS_JEIDA_18 3

According to the reference manual the register expects:

lvdsformat_lvds0_select
2'b00: VESA 24bit
2'b01: JEIDA 24bit
2'b10: JEIDA 18bit
2'b11: VESA 18bit

I only have the RK3568 manual but no PX30 or RK3288 manual, so I can't say if
they changed the register mapping between the SoCs or if it's wrong on
the other SoCs as well.

BTW you correctly set the mask to RK3568_LVDS0_SELECT(3), but for the
PX30 it looks wrong:

return regmap_update_bits(lvds->grf, PX30_LVDS_GRF_PD_VO_CON1,
PX30_LVDS_FORMAT(lvds->format),
PX30_LVDS_FORMAT(lvds->format));

I really think regmap_write() would be better to use here to avoid such
things.

> +
> +static void rk3568_lvds_encoder_enable(struct drm_encoder *encoder)
> +{
> + struct rockchip_lvds *lvds = encoder_to_lvds(encoder);
> + struct drm_display_mode *mode = &encoder->crtc->state->adjusted_mode;

'mode' is unused.

> + int ret;
> +
> + drm_panel_prepare(lvds->panel);
> +
> + ret = rk3568_lvds_poweron(lvds);
> + if (ret) {
> + DRM_DEV_ERROR(lvds->dev, "failed to power on LVDS: %d\n", ret);
> + drm_panel_unprepare(lvds->panel);
> + return;
> + }
> +
> + ret = rk3568_lvds_grf_config(encoder, mode);
> + if (ret) {
> + DRM_DEV_ERROR(lvds->dev, "failed to configure LVDS: %d\n", ret);
> + drm_panel_unprepare(lvds->panel);
> + return;
> + }
> +
> + drm_panel_enable(lvds->panel);
> +}
> +
> +static void rk3568_lvds_encoder_disable(struct drm_encoder *encoder)
> +{
> + struct rockchip_lvds *lvds = encoder_to_lvds(encoder);
> +
> + drm_panel_disable(lvds->panel);
> + rk3568_lvds_poweroff(lvds);
> + drm_panel_unprepare(lvds->panel);
> +}
> +
> static const
> struct drm_encoder_helper_funcs rk3288_lvds_encoder_helper_funcs = {
> .enable = rk3288_lvds_encoder_enable,
> @@ -447,6 +531,13 @@ struct drm_encoder_helper_funcs px30_lvds_encoder_helper_funcs = {
> .atomic_check = rockchip_lvds_encoder_atomic_check,
> };
>
> +static const
> +struct drm_encoder_helper_funcs rk3568_lvds_encoder_helper_funcs = {
> + .enable = rk3568_lvds_encoder_enable,
> + .disable = rk3568_lvds_encoder_disable,
> + .atomic_check = rockchip_lvds_encoder_atomic_check,
> +};
> +
> static int rk3288_lvds_probe(struct platform_device *pdev,
> struct rockchip_lvds *lvds)
> {
> @@ -491,6 +582,26 @@ static int rk3288_lvds_probe(struct platform_device *pdev,
> return 0;
> }
>
> +static int rockchip_lvds_phy_probe(struct platform_device *pdev,
> + struct rockchip_lvds *lvds)
> +{
> + int ret;
> +
> + lvds->dphy = devm_phy_get(&pdev->dev, "dphy");
> + if (IS_ERR(lvds->dphy))
> + return PTR_ERR(lvds->dphy);
> +
> + ret = phy_init(lvds->dphy);
> + if (ret)
> + return ret;
> +
> + ret = phy_set_mode(lvds->dphy, PHY_MODE_LVDS);
> + if (ret)
> + return ret;
> +
> + return phy_power_on(lvds->dphy);
> +}

You factor out the steps done for px30 to a separate function in order
to reuse it on rk3568. You could make a separate patch from this to
make it easier to understand and to verify that there is no functional
change involved for the px30.

Sascha

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