Date:   Fri, 10 Jun 2022 15:40:06 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Liu Ying <victor.liu@....com>
Cc:     dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, andrzej.hajda@...el.com,
        narmstrong@...libre.com, robert.foss@...aro.org, jonas@...boo.se,
        jernej.skrabec@...il.com, airlied@...ux.ie, daniel@...ll.ch,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com, lee.jones@...aro.org,
        mchehab@...nel.org, marcel.ziswiler@...adex.com
Subject: Re: [PATCH v8 06/14] drm/bridge: imx: Add i.MX8qm/qxp display pixel
 link support

Hi Liu,

On Fri, Jun 10, 2022 at 10:09:19AM +0800, Liu Ying wrote:
> On Thu, 2022-06-09 at 12:30 +0300, Laurent Pinchart wrote:
> > On Thu, Jun 09, 2022 at 02:49:23PM +0800, Liu Ying wrote:
> > > This patch adds a drm bridge driver for i.MX8qm/qxp display pixel
> > > link.
> > > The pixel link forms a standard asynchronous linkage between
> > > pixel sources(display controller or camera module) and pixel
> > > consumers(imaging or displays).  It consists of two distinct
> > > functions, a pixel transfer function and a control interface.
> > > 
> > > Reviewed-by: Robert Foss <robert.foss@...aro.org>
> > > Tested-by: Marcel Ziswiler <marcel.ziswiler@...adex.com> # Colibri
> > > iMX8X, LT170410-2WHC, LP156WF1
> > > Signed-off-by: Liu Ying <victor.liu@....com>
> > > ---
> > > Robert, I keep your R-b tag from v5. Let me know if you want me to
> > > drop it, as
> > > v7 contains a fix for checkpatch complaints.
> > > Marcel, as the fix is trivial, I add your T-b tag. Let me know if
> > > you want me
> > > to drop it.
> > > 
> > > v7->v8:
> > > * No change.
> > > 
> > > v6->v7:
> > > * Fix 'Alignment should match open parenthesis' complaints from
> > >   'checkpatch.pl --strict'.
> > > * Add Marcel's T-b tag.
> > > 
> > > v5->v6:
> > > * No change.
> > > 
> > > v4->v5:
> > > * Make a comment occupy a line. (Robert)
> > > * Add Robert's R-b tag.
> > > 
> > > v3->v4:
> > > * No change.
> > > 
> > > v2->v3:
> > > * Drop two macros which help define functions and define them
> > > directly.
> > > * Properly disable all pixel link controls to POR value by calling
> > >   imx8qxp_pixel_link_disable_all_controls() from
> > >   imx8qxp_pixel_link_bridge_probe().
> > > 
> > > v1->v2:
> > > * Rewrite the function to find the next bridge by properly using OF
> > > APIs
> > >   and dropping unnecessary DT validation. (Rob)
> > > 
> > >  drivers/gpu/drm/bridge/imx/Kconfig            |   8 +
> > >  drivers/gpu/drm/bridge/imx/Makefile           |   1 +
> > >  .../gpu/drm/bridge/imx/imx8qxp-pixel-link.c   | 429 ++++++++++++++++++
> > >  3 files changed, 438 insertions(+)
> > >  create mode 100644 drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
> > > 
> > > diff --git a/drivers/gpu/drm/bridge/imx/Kconfig
> > > b/drivers/gpu/drm/bridge/imx/Kconfig
> > > index f1c91b6814a5..4d1f027d07f8 100644
> > > --- a/drivers/gpu/drm/bridge/imx/Kconfig
> > > +++ b/drivers/gpu/drm/bridge/imx/Kconfig
> > > @@ -6,3 +6,11 @@ config DRM_IMX8QXP_PIXEL_COMBINER
> > >  	help
> > >  	  Choose this to enable pixel combiner found in
> > >  	  Freescale i.MX8qm/qxp processors.
> > > +
> > > +config DRM_IMX8QXP_PIXEL_LINK
> > > +	tristate "Freescale i.MX8QM/QXP display pixel link"
> > > +	depends on OF
> > > +	select DRM_KMS_HELPER
> > 
> > Should this depend on (or select) IMX_SCU ?
> 
> Will add 'depends on IMX_SCU'.
> 
> > > +	help
> > > +	  Choose this to enable display pixel link found in
> > > +	  Freescale i.MX8qm/qxp processors.
> > > diff --git a/drivers/gpu/drm/bridge/imx/Makefile
> > > b/drivers/gpu/drm/bridge/imx/Makefile
> > > index 7d7c8d674bf0..c15469fb5789 100644
> > > --- a/drivers/gpu/drm/bridge/imx/Makefile
> > > +++ b/drivers/gpu/drm/bridge/imx/Makefile
> > > @@ -1 +1,2 @@
> > >  obj-$(CONFIG_DRM_IMX8QXP_PIXEL_COMBINER) += imx8qxp-pixel-
> > > combiner.o
> > > +obj-$(CONFIG_DRM_IMX8QXP_PIXEL_LINK) += imx8qxp-pixel-link.o
> > > diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
> > > new file mode 100644
> > > index 000000000000..52b9b96549e1
> > > --- /dev/null
> > > +++ b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
> > > @@ -0,0 +1,429 @@
> > > +// SPDX-License-Identifier: GPL-2.0+
> > > +
> > > +/*
> > > + * Copyright 2020 NXP
> > > + */
> > > +
> > > +#include <linux/firmware/imx/svc/misc.h>
> > > +#include <linux/module.h>
> > > +#include <linux/of.h>
> > > +#include <linux/of_graph.h>
> > > +#include <linux/platform_device.h>
> > > +
> > > +#include <drm/drm_atomic_state_helper.h>
> > > +#include <drm/drm_bridge.h>
> > > +#include <drm/drm_print.h>
> > > +
> > > +#include <dt-bindings/firmware/imx/rsrc.h>
> > > +
> > > +#define DRIVER_NAME		"imx8qxp-display-pixel-link"
> > > +#define PL_MAX_MST_ADDR		3
> > > +#define PL_MAX_NEXT_BRIDGES	2
> > > +
> > > +struct imx8qxp_pixel_link {
> > > +	struct drm_bridge bridge;
> > > +	struct drm_bridge *next_bridge;
> > > +	struct device *dev;
> > > +	struct imx_sc_ipc *ipc_handle;
> > > +	int id;
> > > +	int stream_id;
> > > +	int dc_id;
> > > +	u32 sink_rsc;
> > > +	u32 mst_addr;
> > > +	u8 mst_addr_ctrl;
> > > +	u8 mst_en_ctrl;
> > > +	u8 mst_vld_ctrl;
> > > +	u8 sync_ctrl;
> > > +};
> > > +
> > > +static void imx8qxp_pixel_link_enable_mst_en(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
> > > +				      pl->mst_en_ctrl, true);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to enable DC%d stream%d pixel link mst_en: %d\n",
> > > +			      pl->dc_id, pl->stream_id, ret);
> > > +}
> > > +
> > > +static void imx8qxp_pixel_link_enable_mst_vld(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
> > > +				      pl->mst_vld_ctrl, true);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to enable DC%d stream%d pixel link mst_vld: %d\n",
> > > +			      pl->dc_id, pl->stream_id, ret);
> > > +}
> > > +
> > > +static void imx8qxp_pixel_link_enable_sync(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
> > > +				      pl->sync_ctrl, true);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to enable DC%d stream%d pixel link sync: %d\n",
> > > +			      pl->dc_id, pl->stream_id, ret);
> > > +}
> > > +
> > > +static int imx8qxp_pixel_link_disable_mst_en(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
> > > +				      pl->mst_en_ctrl, false);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to disable DC%d stream%d pixel link mst_en: %d\n",
> > > +			      pl->dc_id, pl->stream_id, ret);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static int imx8qxp_pixel_link_disable_mst_vld(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
> > > +				      pl->mst_vld_ctrl, false);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to disable DC%d stream%d pixel link mst_vld: %d\n",
> > > +			      pl->dc_id, pl->stream_id, ret);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static int imx8qxp_pixel_link_disable_sync(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
> > > +				      pl->sync_ctrl, false);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to disable DC%d stream%d pixel link sync: %d\n",
> > > +			      pl->dc_id, pl->stream_id, ret);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static void imx8qxp_pixel_link_set_mst_addr(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx_sc_misc_set_control(pl->ipc_handle,
> > > +				      pl->sink_rsc, pl->mst_addr_ctrl,
> > > +				      pl->mst_addr);
> > > +	if (ret)
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "failed to set DC%d stream%d pixel link mst addr(%u): %d\n",
> > > +			      pl->dc_id, pl->stream_id, pl->mst_addr, ret);
> > > +}
> > > +
> > > +static int imx8qxp_pixel_link_bridge_attach(struct drm_bridge *bridge,
> > > +					    enum drm_bridge_attach_flags flags)
> > > +{
> > > +	struct imx8qxp_pixel_link *pl = bridge->driver_private;
> > > +
> > > +	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
> > > +		DRM_DEV_ERROR(pl->dev,
> > > +			      "do not support creating a drm_connector\n");
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +	if (!bridge->encoder) {
> > > +		DRM_DEV_ERROR(pl->dev, "missing encoder\n");
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	return drm_bridge_attach(bridge->encoder,
> > > +				 pl->next_bridge, bridge,
> > > +				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > > +}
> > > +
> > > +static void
> > > +imx8qxp_pixel_link_bridge_mode_set(struct drm_bridge *bridge,
> > > +				   const struct drm_display_mode *mode,
> > > +				   const struct drm_display_mode *adjusted_mode)
> > > +{
> > > +	struct imx8qxp_pixel_link *pl = bridge->driver_private;
> > > +
> > > +	imx8qxp_pixel_link_set_mst_addr(pl);
> > > +}
> > > +
> > > +static void
> > > +imx8qxp_pixel_link_bridge_atomic_enable(struct drm_bridge *bridge,
> > > +					struct drm_bridge_state
> > > *old_bridge_state)
> > > +{
> > > +	struct imx8qxp_pixel_link *pl = bridge->driver_private;
> > > +
> > > +	imx8qxp_pixel_link_enable_mst_en(pl);
> > > +	imx8qxp_pixel_link_enable_mst_vld(pl);
> > > +	imx8qxp_pixel_link_enable_sync(pl);
> > > +}
> > > +
> > > +static void
> > > +imx8qxp_pixel_link_bridge_atomic_disable(struct drm_bridge *bridge,
> > > +					 struct drm_bridge_state
> > > *old_bridge_state)
> > > +{
> > > +	struct imx8qxp_pixel_link *pl = bridge->driver_private;
> > > +
> > > +	imx8qxp_pixel_link_disable_mst_en(pl);
> > > +	imx8qxp_pixel_link_disable_mst_vld(pl);
> > > +	imx8qxp_pixel_link_disable_sync(pl);
> > > +}
> > > +
> > > +static const u32 imx8qxp_pixel_link_bus_output_fmts[] = {
> > > +	MEDIA_BUS_FMT_RGB888_1X36_CPADLO,
> > > +	MEDIA_BUS_FMT_RGB666_1X36_CPADLO,
> > > +};
> > > +
> > > +static bool imx8qxp_pixel_link_bus_output_fmt_supported(u32 fmt)
> > > +{
> > > +	int i;
> > > +
> > > +	for (i = 0; i < ARRAY_SIZE(imx8qxp_pixel_link_bus_output_fmts); i++) {
> > > +		if (imx8qxp_pixel_link_bus_output_fmts[i] == fmt)
> > > +			return true;
> > > +	}
> > > +
> > > +	return false;
> > > +}
> > > +
> > > +static u32 *
> > > +imx8qxp_pixel_link_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
> > > +						    struct drm_bridge_state *bridge_state,
> > > +						    struct drm_crtc_state *crtc_state,
> > > +						    struct drm_connector_state *conn_state,
> > > +						    u32 output_fmt,
> > > +						    unsigned int
> > > *num_input_fmts)
> > > +{
> > > +	u32 *input_fmts;
> > > +
> > > +	if (!imx8qxp_pixel_link_bus_output_fmt_supported(output_fmt))
> > > +		return NULL;
> > > +
> > > +	*num_input_fmts = 1;
> > > +
> > > +	input_fmts = kmalloc(sizeof(*input_fmts), GFP_KERNEL);
> > > +	if (!input_fmts)
> > > +		return NULL;
> > > +
> > > +	input_fmts[0] = output_fmt;
> > > +
> > > +	return input_fmts;
> > > +}
> > > +
> > > +static u32 *
> > > +imx8qxp_pixel_link_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
> > > +						     struct drm_bridge_state *bridge_state,
> > > +						     struct drm_crtc_state *crtc_state,
> > > +						     struct drm_connector_state *conn_state,
> > > +						     unsigned int
> > > *num_output_fmts)
> > > +{
> > > +	*num_output_fmts = ARRAY_SIZE(imx8qxp_pixel_link_bus_output_fmts);
> > > +	return kmemdup(imx8qxp_pixel_link_bus_output_fmts,
> > > +			sizeof(imx8qxp_pixel_link_bus_output_fmts), GFP_KERNEL);
> > > +}
> > > +
> > > +static const struct drm_bridge_funcs imx8qxp_pixel_link_bridge_funcs = {
> > > +	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
> > > +	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
> > > +	.atomic_reset		= drm_atomic_helper_bridge_reset,
> > > +	.attach			= imx8qxp_pixel_link_bridge_attach,
> > > +	.mode_set		= imx8qxp_pixel_link_bridge_mode_set,
> > > +	.atomic_enable		= imx8qxp_pixel_link_bridge_atomic_enable,
> > > +	.atomic_disable		= imx8qxp_pixel_link_bridge_atomic_disable,
> > > +	.atomic_get_input_bus_fmts =
> > > +			imx8qxp_pixel_link_bridge_atomic_get_input_bus_fmts,
> > > +	.atomic_get_output_bus_fmts =
> > > +			imx8qxp_pixel_link_bridge_atomic_get_output_bus_fmts,
> > > +};
> > > +
> > > +static int imx8qxp_pixel_link_disable_all_controls(struct
> > > imx8qxp_pixel_link *pl)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = imx8qxp_pixel_link_disable_mst_en(pl);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	ret = imx8qxp_pixel_link_disable_mst_vld(pl);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	return imx8qxp_pixel_link_disable_sync(pl);
> > > +}
> > > +
> > > +static struct drm_bridge *
> > > +imx8qxp_pixel_link_find_next_bridge(struct imx8qxp_pixel_link *pl)
> > > +{
> > > +	struct device_node *np = pl->dev->of_node;
> > > +	struct device_node *port, *remote;
> > > +	struct drm_bridge *next_bridge[PL_MAX_NEXT_BRIDGES];
> > > +	u32 port_id;
> > > +	bool found_port = false;
> > > +	int reg, ep_cnt = 0;
> > > +	/* select the first next bridge by default */
> > > +	int bridge_sel = 0;
> > > +
> > > +	for (port_id = 1; port_id <= PL_MAX_MST_ADDR + 1; port_id++) {
> > > +		port = of_graph_get_port_by_id(np, port_id);
> > > +		if (!port)
> > > +			continue;
> > > +
> > > +		if (of_device_is_available(port)) {
> > > +			found_port = true;
> > > +			of_node_put(port);
> > > +			break;
> > > +		}
> > > +
> > > +		of_node_put(port);
> > > +	}
> > > +
> > > +	if (!found_port) {
> > > +		DRM_DEV_ERROR(pl->dev, "no available output port\n");
> > > +		return ERR_PTR(-ENODEV);
> > > +	}
> > > +
> > > +	for (reg = 0; reg < PL_MAX_NEXT_BRIDGES; reg++) {
> > > +		remote = of_graph_get_remote_node(np, port_id, reg);
> > > +		if (!remote)
> > > +			continue;
> > > +
> > > +		if (!of_device_is_available(remote->parent)) {
> > > +			DRM_DEV_DEBUG(pl->dev,
> > > +				      "port%u endpoint%u remote parent is not available\n",
> > > +				      port_id, reg);
> > > +			of_node_put(remote);
> > > +			continue;
> > > +		}
> > > +
> > > +		next_bridge[ep_cnt] = of_drm_find_bridge(remote);
> > > +		if (!next_bridge[ep_cnt]) {
> > > +			of_node_put(remote);
> > > +			return ERR_PTR(-EPROBE_DEFER);
> > > +		}
> > > +
> > > +		/* specially select the next bridge with companion PXL2DPI */
> > > +		if (of_find_property(remote, "fsl,companion-pxl2dpi", NULL))
> > > +			bridge_sel = ep_cnt;
> > > +
> > > +		ep_cnt++;
> > > +
> > > +		of_node_put(remote);
> > > +	}
> > > +
> > > +	pl->mst_addr = port_id - 1;
> > > +
> > > +	return next_bridge[bridge_sel];
> > > +}
> > > +
> > > +static int imx8qxp_pixel_link_bridge_probe(struct platform_device *pdev)
> > > +{
> > > +	struct imx8qxp_pixel_link *pl;
> > > +	struct device *dev = &pdev->dev;
> > > +	struct device_node *np = dev->of_node;
> > > +	int ret;
> > > +
> > > +	pl = devm_kzalloc(dev, sizeof(*pl), GFP_KERNEL);
> > > +	if (!pl)
> > > +		return -ENOMEM;
> > > +
> > > +	ret = imx_scu_get_handle(&pl->ipc_handle);
> > > +	if (ret) {
> > > +		if (ret != -EPROBE_DEFER)
> > > +			DRM_DEV_ERROR(dev, "failed to get SCU ipc handle: %d\n",
> > > +				      ret);
> > > +		return ret;
> > > +	}
> > > +
> > > +	pl->id = of_alias_get_id(np, "dc_pl");
> > 
> > Could we avoid relying on aliases ? I'd add an id property to the DT
> > node instead, or possibly even better a dc id and a stream id.
> 
> Will add two properties for dc id and stream id.
> Do 'fsl,dc-id' and 'fsl,dc-stream-id' look ok?

Looks good to me.

-- 
Regards,

Laurent Pinchart

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