Re: [PATCH 2/2] drm: renesas: rzg2l_mipi_dsi: Fix the power-on sequence
From: Hugo Villeneuve
Date: Tue Mar 17 2026 - 11:02:14 EST
Hi Biju,
On Tue, 17 Mar 2026 12:36:01 +0000
Biju <biju.das.au@xxxxxxxxx> wrote:
> From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
>
> Move reset_control_deassert() and reset_control_assert() from
> rzg2l_mipi_dsi_dphy_init()/rzg2l_mipi_dsi_dphy_exit() to
> atomic_pre_enable() and atomic_post_disable() respectively, and move
> rzg2l_mipi_dsi_set_display_timing() from atomic_pre_enable() to
> atomic_enable(), to align with the power-on sequence described in
> Figure 34.5 of section "34.4.2.1 Reset" of the RZ/G2L hardware manual
> Rev.1.50 May 2025.
>
> According to the hardware manual, LINK registers must be written before
> deasserting CMN_RSTB, and the 1ms delay is retained in atomic_pre_enable()
> after the deassert.
>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Seems to me like this should be backported to stable branches (missing Fixes / Cc: stable tags)?
> ---
> .../gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 27 +++++++++++--------
> 1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> index e53b48e4de56..9053ce037b75 100644
> --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> @@ -484,7 +484,6 @@ static int rzg2l_mipi_dsi_dphy_init(struct rzg2l_mipi_dsi *dsi,
> u32 dphytim1;
> u32 dphytim2;
> u32 dphytim3;
> - int ret;
>
> /* All DSI global operation timings are set with recommended setting */
> for (i = 0; i < ARRAY_SIZE(rzg2l_mipi_dsi_global_timings); ++i) {
> @@ -524,12 +523,6 @@ static int rzg2l_mipi_dsi_dphy_init(struct rzg2l_mipi_dsi *dsi,
> rzg2l_mipi_dsi_phy_write(dsi, DSIDPHYTIM2, dphytim2);
> rzg2l_mipi_dsi_phy_write(dsi, DSIDPHYTIM3, dphytim3);
>
> - ret = reset_control_deassert(dsi->rstc);
> - if (ret < 0)
> - return ret;
> -
> - fsleep(1000);
> -
> return 0;
> }
>
> @@ -541,8 +534,6 @@ static void rzg2l_mipi_dsi_dphy_exit(struct rzg2l_mipi_dsi *dsi)
>
> dphyctrl0 &= ~(DSIDPHYCTRL0_EN_LDO1200 | DSIDPHYCTRL0_EN_BGR);
> rzg2l_mipi_dsi_phy_write(dsi, DSIDPHYCTRL0, dphyctrl0);
> -
> - reset_control_assert(dsi->rstc);
> }
>
> static int rzg2l_dphy_conf_clks(struct rzg2l_mipi_dsi *dsi, unsigned long mode_freq,
> @@ -1030,24 +1021,37 @@ static void rzg2l_mipi_dsi_atomic_pre_enable(struct drm_bridge *bridge,
> connector = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
> crtc = drm_atomic_get_new_connector_state(state, connector)->crtc;
> mode = &drm_atomic_get_new_crtc_state(state, crtc)->adjusted_mode;
> -
This is not related to your commit message (coding style change).
> ret = rzg2l_mipi_dsi_startup(dsi, mode);
> if (ret < 0)
> return;
>
> - rzg2l_mipi_dsi_set_display_timing(dsi, mode);
> + ret = reset_control_deassert(dsi->rstc);
> + if (ret < 0)
> + return;
> +
> + if (dsi->rstc)
This seems new and not documented in the commit message? Is this a fix?
> + fsleep(1000);
> }
>
> static void rzg2l_mipi_dsi_atomic_enable(struct drm_bridge *bridge,
> struct drm_atomic_state *state)
> {
> struct rzg2l_mipi_dsi *dsi = bridge_to_rzg2l_mipi_dsi(bridge);
> + const struct drm_display_mode *mode;
> + struct drm_connector *connector;
> + struct drm_crtc *crtc;
> int ret;
>
> ret = rzg2l_mipi_dsi_start_hs_clock(dsi);
> if (ret < 0)
> goto err_stop;
>
> + connector = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
> + crtc = drm_atomic_get_new_connector_state(state, connector)->crtc;
> + mode = &drm_atomic_get_new_crtc_state(state, crtc)->adjusted_mode;
> +
> + rzg2l_mipi_dsi_set_display_timing(dsi, mode);
> +
> ret = rzg2l_mipi_dsi_start_video(dsi);
> if (ret < 0)
> goto err_stop_clock;
> @@ -1074,6 +1078,7 @@ static void rzg2l_mipi_dsi_atomic_post_disable(struct drm_bridge *bridge,
> {
> struct rzg2l_mipi_dsi *dsi = bridge_to_rzg2l_mipi_dsi(bridge);
>
> + reset_control_assert(dsi->rstc);
> rzg2l_mipi_dsi_stop(dsi);
> }
>
> --
> 2.43.0
>
>
--
Hugo Villeneuve <hugo@xxxxxxxxxxx>