[PATCH 3/3] drm: rcar-du: fix DSI enable & disable sequence
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Fri Aug 19 01:34:56 UTC 2022
Hi Tomi,
Thank you for the patch.
On Wed, Aug 17, 2022 at 04:28:03PM +0300, Tomi Valkeinen wrote:
> From: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
>
> The rcar crtc depends on the clock provided from the rcar DSI bridge.
> When the DSI bridge is disabled, the clock is stopped, which causes the
> crtc disable to timeout.
>
> Also, while I have no issue with the enable, the documentation suggests
> to enable the DSI before the crtc so that the crtc has its clock enabled
> at enable time. This is also not done by the current driver.
>
> To fix this, we need to keep the DSI bridge enabled until the crtc has
> disabled itself, and enable the DSI bridge before crtc enables itself.
>
> Add functions (rcar_mipi_dsi_atomic_early_enable and
> rcar_mipi_dsi_atomic_late_disable) to the rcar DSI bridge driver which
> the rcar driver can use to enable/disable the DSI clock when needed.
> This is similar to what is already done with the rcar LVDS bridge.
I had hoped we could avoid that :-(
I wonder if we could instead rely on the pre_enable/post_disable bridge
operations, with a custom commit tail implementation to order those
before/after the CRTC enable/disable respectively. That would be pretty
complex though, so probably not worth it.
Thinking more about this, I wonder why pre_enable is not called before
enabling the CRTC in the DRM atomic helpers. That would make more sense
to me, but I suppose changing it would break too many things ? I think
it should at least be discussed to figure out if it was a historical
oversight or if there was a good reason. It's *really* not nice to poke
holes through the abstraction layers like this.
> Also add a new function, rcar_mipi_dsi_stop_video(), called from
> rcar_mipi_dsi_atomic_enable so that the DSI TX gets disabled at the
> correct time, even if the clocks are still kept enabled.
I think this should be split to a separate patch, possibly before this
one, it addresses a separate issue.
> And, while possibly not strictly needed, clear clock related enable bits
> in rcar_mipi_dsi_atomic_late_disable to mirror the sequence done in
> rcar_mipi_dsi_startup() (via rcar_mipi_dsi_atomic_early_enable).
And this too should be a separate patch, possibly bundled with
rcar_mipi_dsi_stop_video().
Have you checked in the BSP code to see if they do the same at disable
time ?
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
> ---
> drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 25 +++++++++
> drivers/gpu/drm/rcar-du/rcar_du_drv.h | 2 +
> drivers/gpu/drm/rcar-du/rcar_du_encoder.c | 4 ++
> drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 63 +++++++++++++++++++++--
> drivers/gpu/drm/rcar-du/rcar_mipi_dsi.h | 32 ++++++++++++
> 5 files changed, 121 insertions(+), 5 deletions(-)
> create mode 100644 drivers/gpu/drm/rcar-du/rcar_mipi_dsi.h
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index fd3b94649a01..51fd1d99f4e8 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -29,6 +29,7 @@
> #include "rcar_du_regs.h"
> #include "rcar_du_vsp.h"
> #include "rcar_lvds.h"
> +#include "rcar_mipi_dsi.h"
>
> static u32 rcar_du_crtc_read(struct rcar_du_crtc *rcrtc, u32 reg)
> {
> @@ -733,6 +734,18 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
> rcar_cmm_enable(rcrtc->cmm);
> rcar_du_crtc_get(rcrtc);
>
A comment here similar to the LVDS case would be useful. I would
actually move this below the LVDS code, and write
/*
* Similarly, on V3U, ...
*/
> + if ((rcdu->info->dsi_clk_mask & BIT(rcrtc->index)) &&
> + (rstate->outputs &
> + (BIT(RCAR_DU_OUTPUT_DSI0) | BIT(RCAR_DU_OUTPUT_DSI1)))) {
> + struct drm_bridge *bridge = rcdu->dsi[rcrtc->index];
> +
> + /*
> + * Enable the DSI clock output.
> + */
> +
> + rcar_mipi_dsi_atomic_early_enable(bridge, state);
> + }
I was wondering if we could merge the DSI and LVDS clock enabling code,
including merging the lvds and dsi fields in rcar_du_device, but it
doesn't seem it will be very clean here.
> +
> /*
> * On D3/E3 the dot clock is provided by the LVDS encoder attached to
> * the DU channel. We need to enable its clock output explicitly if
> @@ -769,6 +782,18 @@ static void rcar_du_crtc_atomic_disable(struct drm_crtc *crtc,
> rcar_du_crtc_stop(rcrtc);
> rcar_du_crtc_put(rcrtc);
>
> + if ((rcdu->info->dsi_clk_mask & BIT(rcrtc->index)) &&
> + (rstate->outputs &
> + (BIT(RCAR_DU_OUTPUT_DSI0) | BIT(RCAR_DU_OUTPUT_DSI1)))) {
> + struct drm_bridge *bridge = rcdu->dsi[rcrtc->index];
> +
> + /*
> + * Disable the DSI clock output.
> + */
> +
> + rcar_mipi_dsi_atomic_late_disable(bridge);
> + }
> +
> if (rcdu->info->lvds_clk_mask & BIT(rcrtc->index) &&
> rstate->outputs == BIT(RCAR_DU_OUTPUT_DPAD0)) {
> struct drm_bridge *bridge = rcdu->lvds[rcrtc->index];
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> index 712389c7b3d0..5cfa2bb7ad93 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> @@ -92,6 +92,7 @@ struct rcar_du_device_info {
> #define RCAR_DU_MAX_GROUPS DIV_ROUND_UP(RCAR_DU_MAX_CRTCS, 2)
> #define RCAR_DU_MAX_VSPS 4
> #define RCAR_DU_MAX_LVDS 2
> +#define RCAR_DU_MAX_DSI 2
>
> struct rcar_du_device {
> struct device *dev;
> @@ -108,6 +109,7 @@ struct rcar_du_device {
> struct platform_device *cmms[RCAR_DU_MAX_CRTCS];
> struct rcar_du_vsp vsps[RCAR_DU_MAX_VSPS];
> struct drm_bridge *lvds[RCAR_DU_MAX_LVDS];
> + struct drm_bridge *dsi[RCAR_DU_MAX_DSI];
>
> struct {
> struct drm_property *colorkey;
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> index 60d6be78323b..ac93e08e8af4 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> @@ -84,6 +84,10 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> if (output == RCAR_DU_OUTPUT_LVDS0 ||
> output == RCAR_DU_OUTPUT_LVDS1)
> rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = bridge;
> +
> + if (output == RCAR_DU_OUTPUT_DSI0 ||
> + output == RCAR_DU_OUTPUT_DSI1)
> + rcdu->dsi[output - RCAR_DU_OUTPUT_DSI0] = bridge;
> }
>
> /*
> diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> index 62f7eb84ab01..1ec40e40fd08 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> @@ -542,6 +542,34 @@ static int rcar_mipi_dsi_start_video(struct rcar_mipi_dsi *dsi)
> return 0;
> }
>
> +static void rcar_mipi_dsi_stop_video(struct rcar_mipi_dsi *dsi)
> +{
> + u32 status;
> + int ret;
> +
> + /* Disable transmission in video mode. */
> + rcar_mipi_dsi_clr(dsi, TXVMCR, TXVMCR_EN_VIDEO);
> +
> + ret = read_poll_timeout(rcar_mipi_dsi_read, status,
> + !(status & TXVMSR_ACT),
> + 2000, 100000, false, dsi, TXVMSR);
> + if (ret < 0) {
> + dev_err(dsi->dev, "Failed to disable video transmission\n");
> + return;
> + }
> +
> + /* Assert video FIFO clear. */
> + rcar_mipi_dsi_set(dsi, TXVMCR, TXVMCR_VFCLR);
> +
> + ret = read_poll_timeout(rcar_mipi_dsi_read, status,
> + !(status & TXVMSR_VFRDY),
> + 2000, 100000, false, dsi, TXVMSR);
> + if (ret < 0) {
> + dev_err(dsi->dev, "Failed to assert video FIFO clear\n");
> + return;
> + }
> +}
> +
> /* -----------------------------------------------------------------------------
> * Bridge
> */
> @@ -558,7 +586,22 @@ static int rcar_mipi_dsi_attach(struct drm_bridge *bridge,
> static void rcar_mipi_dsi_atomic_enable(struct drm_bridge *bridge,
> struct drm_bridge_state *old_bridge_state)
> {
> - struct drm_atomic_state *state = old_bridge_state->base.state;
> + struct rcar_mipi_dsi *dsi = bridge_to_rcar_mipi_dsi(bridge);
> +
> + rcar_mipi_dsi_start_video(dsi);
> +}
> +
> +static void rcar_mipi_dsi_atomic_disable(struct drm_bridge *bridge,
> + struct drm_bridge_state *old_bridge_state)
> +{
> + struct rcar_mipi_dsi *dsi = bridge_to_rcar_mipi_dsi(bridge);
> +
> + rcar_mipi_dsi_stop_video(dsi);
> +}
> +
> +void rcar_mipi_dsi_atomic_early_enable(struct drm_bridge *bridge,
> + struct drm_atomic_state *state)
> +{
> struct rcar_mipi_dsi *dsi = bridge_to_rcar_mipi_dsi(bridge);
> const struct drm_display_mode *mode;
> struct drm_connector *connector;
> @@ -586,8 +629,6 @@ static void rcar_mipi_dsi_atomic_enable(struct drm_bridge *bridge,
> if (ret < 0)
> goto err_dsi_start_hs;
>
> - rcar_mipi_dsi_start_video(dsi);
> -
> return;
>
> err_dsi_start_hs:
> @@ -595,15 +636,27 @@ static void rcar_mipi_dsi_atomic_enable(struct drm_bridge *bridge,
> err_dsi_startup:
> rcar_mipi_dsi_clk_disable(dsi);
> }
> +EXPORT_SYMBOL_GPL(rcar_mipi_dsi_atomic_early_enable);
>
> -static void rcar_mipi_dsi_atomic_disable(struct drm_bridge *bridge,
> - struct drm_bridge_state *old_bridge_state)
> +void rcar_mipi_dsi_atomic_late_disable(struct drm_bridge *bridge)
> {
> struct rcar_mipi_dsi *dsi = bridge_to_rcar_mipi_dsi(bridge);
>
> + rcar_mipi_dsi_clr(dsi, VCLKEN, VCLKEN_CKEN);
> +
> + /* Disable DOT clock */
> + rcar_mipi_dsi_clr(dsi, VCLKSET, VCLKSET_CKEN);
> +
> + /* CFGCLK disable */
> + rcar_mipi_dsi_clr(dsi, CFGCLKSET, CFGCLKSET_CKEN);
> +
> + /* LPCLK disable */
> + rcar_mipi_dsi_clr(dsi, LPCLKSET, LPCLKSET_CKEN);
> +
> rcar_mipi_dsi_shutdown(dsi);
> rcar_mipi_dsi_clk_disable(dsi);
> }
> +EXPORT_SYMBOL_GPL(rcar_mipi_dsi_atomic_late_disable);
>
> static enum drm_mode_status
> rcar_mipi_dsi_bridge_mode_valid(struct drm_bridge *bridge,
> diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.h b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.h
> new file mode 100644
> index 000000000000..1764abf65a34
> --- /dev/null
> +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * R-Car DSI Encoder
> + *
> + * Copyright (C) 2022 Renesas Electronics Corporation
> + *
> + * Contact: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
> + */
> +
> +#ifndef __RCAR_MIPI_DSI_H__
> +#define __RCAR_MIPI_DSI_H__
> +
> +struct drm_bridge;
> +struct drm_atomic_state;
Alphabetical order please.
> +
> +#if IS_ENABLED(CONFIG_DRM_RCAR_MIPI_DSI)
> +void rcar_mipi_dsi_atomic_early_enable(struct drm_bridge *bridge,
> + struct drm_atomic_state *state);
> +void rcar_mipi_dsi_atomic_late_disable(struct drm_bridge *bridge);
It would be nice to have a naming scheme consistent with rcar_lvds.h.
That would mean rcar_mipi_dsi_clk_{enable,disable}(), or renaming the
LVDS functions to match whatever name would be picked here.
We could name the functions pre_enable/post_disable to show what they
should really be, if it wasn't for the DRM atomic helpers calling the
bridge operations at the wrong time.
> +#else
> +static inline void
> +rcar_mipi_dsi_atomic_early_enable(struct drm_bridge *bridge,
> + struct drm_atomic_state *state)
> +{
> +}
> +
> +void rcar_mipi_dsi_atomic_late_disable(struct drm_bridge *bridge)
> +{
> +}
> +#endif /* CONFIG_DRM_RCAR_MIPI_DSI */
> +
> +#endif /* __RCAR_MIPI_DSI_H__ */
--
Regards,
Laurent Pinchart
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