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Subject: Re: [PATCH v4 05/14] drm/bridge: imx: Add i.MX8qm/qxp pixel
 combiner support
From:   Liu Ying <victor.liu@nxp.com>
To:     Robert Foss <robert.foss@linaro.org>
Cc:     dri-devel <dri-devel@lists.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-media <linux-media@vger.kernel.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de,
        Fabio Estevam <festevam@gmail.com>, linux-imx@nxp.com,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>, kishon@ti.com,
        Vinod Koul <vkoul@kernel.org>
Date:   Tue, 02 Mar 2021 09:36:14 +0800
In-Reply-To: <CAG3jFyuNVdbqdjfOaRmKFVDS30RCdUVp6NURfa3osiaqu462pA@mail.gmail.com>
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         <CAG3jFyuNVdbqdjfOaRmKFVDS30RCdUVp6NURfa3osiaqu462pA@mail.gmail.com>
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On Mon, 2021-03-01 at 11:56 +0100, Robert Foss wrote:
> On Mon, 1 Mar 2021 at 10:07, Liu Ying <victor.liu@nxp.com> wrote:
> > Hi Robert,
> > 
> > On Fri, 2021-02-26 at 14:07 +0100, Robert Foss wrote:
> > > Hey Liu,
> > > 
> > > With the below nit straightened out, feel free to add my r-b.
> > > 
> > > Reviewed-by: Robert Foss <robert.foss@linaro.org>
> > 
> > Thanks for reviewing this patch.
> > 
> > > On Thu, 18 Feb 2021 at 04:58, Liu Ying <victor.liu@nxp.com> wrote:
> > > > This patch adds a drm bridge driver for i.MX8qm/qxp pixel combiner.
> > > > The pixel combiner takes two output streams from a single display
> > > > controller and manipulates the two streams to support a number
> > > > of modes(bypass, pixel combine, YUV444 to YUV422, split_RGB) configured
> > > > as either one screen, two screens, or virtual screens.  The pixel
> > > > combiner is also responsible for generating some of the control signals
> > > > for the pixel link output channel.  For now, the driver only supports
> > > > the bypass mode.
> > > > 
> > > > Signed-off-by: Liu Ying <victor.liu@nxp.com>
> > > > ---
> > > > v3->v4:
> > > > * No change.
> > > > 
> > > > v2->v3:
> > > > * No change.
> > > > 
> > > > v1->v2:
> > > > * No change.
> > > > 
> > > >  drivers/gpu/drm/bridge/Kconfig                     |   2 +
> > > >  drivers/gpu/drm/bridge/Makefile                    |   1 +
> > > >  drivers/gpu/drm/bridge/imx/Kconfig                 |   8 +
> > > >  drivers/gpu/drm/bridge/imx/Makefile                |   1 +
> > > >  .../gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c    | 452 +++++++++++++++++++++
> > > >  5 files changed, 464 insertions(+)
> > > >  create mode 100644 drivers/gpu/drm/bridge/imx/Kconfig
> > > >  create mode 100644 drivers/gpu/drm/bridge/imx/Makefile
> > > >  create mode 100644 drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c
> > > > 
> > > > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> > > > index e4110d6c..84944e0 100644
> > > > --- a/drivers/gpu/drm/bridge/Kconfig
> > > > +++ b/drivers/gpu/drm/bridge/Kconfig
> > > > @@ -256,6 +256,8 @@ source "drivers/gpu/drm/bridge/adv7511/Kconfig"
> > > > 
> > > >  source "drivers/gpu/drm/bridge/cadence/Kconfig"
> > > > 
> > > > +source "drivers/gpu/drm/bridge/imx/Kconfig"
> > > > +
> > > >  source "drivers/gpu/drm/bridge/synopsys/Kconfig"
> > > > 
> > > >  endmenu
> > > > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> > > > index 86e7acc..bc80cae 100644
> > > > --- a/drivers/gpu/drm/bridge/Makefile
> > > > +++ b/drivers/gpu/drm/bridge/Makefile
> > > > @@ -27,4 +27,5 @@ obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
> > > > 
> > > >  obj-y += analogix/
> > > >  obj-y += cadence/
> > > > +obj-y += imx/
> > > >  obj-y += synopsys/
> > > > diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig
> > > > new file mode 100644
> > > > index 00000000..f1c91b6
> > > > --- /dev/null
> > > > +++ b/drivers/gpu/drm/bridge/imx/Kconfig
> > > > @@ -0,0 +1,8 @@
> > > > +config DRM_IMX8QXP_PIXEL_COMBINER
> > > > +       tristate "Freescale i.MX8QM/QXP pixel combiner"
> > > > +       depends on OF
> > > > +       depends on COMMON_CLK
> > > > +       select DRM_KMS_HELPER
> > > > +       help
> > > > +         Choose this to enable pixel combiner found in
> > > > +         Freescale i.MX8qm/qxp processors.
> > > > diff --git a/drivers/gpu/drm/bridge/imx/Makefile b/drivers/gpu/drm/bridge/imx/Makefile
> > > > new file mode 100644
> > > > index 00000000..7d7c8d6
> > > > --- /dev/null
> > > > +++ b/drivers/gpu/drm/bridge/imx/Makefile
> > > > @@ -0,0 +1 @@
> > > > +obj-$(CONFIG_DRM_IMX8QXP_PIXEL_COMBINER) += imx8qxp-pixel-combiner.o
> > > > diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c
> > > > new file mode 100644
> > > > index 00000000..cd5b1be
> > > > --- /dev/null
> > > > +++ b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c
> > > > @@ -0,0 +1,452 @@
> > > > +// SPDX-License-Identifier: GPL-2.0+
> > > > +
> > > > +/*
> > > > + * Copyright 2020 NXP
> > > > + */
> > > > +
> > > > +#include <linux/bitfield.h>
> > > > +#include <linux/clk.h>
> > > > +#include <linux/delay.h>
> > > > +#include <linux/module.h>
> > > > +#include <linux/of.h>
> > > > +#include <linux/of_graph.h>
> > > > +#include <linux/platform_device.h>
> > > > +#include <linux/pm_runtime.h>
> > > > +
> > > > +#include <drm/drm_atomic_state_helper.h>
> > > > +#include <drm/drm_bridge.h>
> > > > +#include <drm/drm_print.h>
> > > > +
> > > > +#define PC_CTRL_REG                    0x0
> > > > +#define  PC_COMBINE_ENABLE             BIT(0)
> > > > +#define  PC_DISP_BYPASS(n)             BIT(1 + 21 * (n))
> > > > +#define  PC_DISP_HSYNC_POLARITY(n)     BIT(2 + 11 * (n))
> > > > +#define  PC_DISP_HSYNC_POLARITY_POS(n) DISP_HSYNC_POLARITY(n)
> > > > +#define  PC_DISP_VSYNC_POLARITY(n)     BIT(3 + 11 * (n))
> > > > +#define  PC_DISP_VSYNC_POLARITY_POS(n) DISP_VSYNC_POLARITY(n)
> > > > +#define  PC_DISP_DVALID_POLARITY(n)    BIT(4 + 11 * (n))
> > > > +#define  PC_DISP_DVALID_POLARITY_POS(n)        DISP_DVALID_POLARITY(n)
> > > > +#define  PC_VSYNC_MASK_ENABLE          BIT(5)
> > > > +#define  PC_SKIP_MODE                  BIT(6)
> > > > +#define  PC_SKIP_NUMBER_MASK           GENMASK(12, 7)
> > > > +#define  PC_SKIP_NUMBER(n)             FIELD_PREP(PC_SKIP_NUMBER_MASK, (n))
> > > > +#define  PC_DISP0_PIX_DATA_FORMAT_MASK GENMASK(18, 16)
> > > > +#define  PC_DISP0_PIX_DATA_FORMAT(fmt) \
> > > > +                               FIELD_PREP(PC_DISP0_PIX_DATA_FORMAT_MASK, (fmt))
> > > > +#define  PC_DISP1_PIX_DATA_FORMAT_MASK GENMASK(21, 19)
> > > > +#define  PC_DISP1_PIX_DATA_FORMAT(fmt) \
> > > > +                               FIELD_PREP(PC_DISP1_PIX_DATA_FORMAT_MASK, (fmt))
> > > > +
> > > > +#define PC_BUF_PARA_REG                        0x10
> > > 
> > > This register is unused, keeping it in here to avoid future headaches
> > > seems like a good idea.
> > 
> > Yes, for now, this register is unused.
> > It will be used to set the below PC_BUF_ACTIVE_DEPTH field when
> > non-bypass modes are enabled, I think.
> > 
> > Though you said 'keeping it', you actually want me to drop it for now,
> > right?
> 
> If there is a 2nd series coming which will enable non-bypass modes,
> then maybe add it in that series instead.

Ok, I'll drop PC_BUF_PARA_REG for now in the next version.

Thanks,
Liu Ying

> 
> > > > +#define  PC_BUF_ACTIVE_DEPTH_MASK      GENMASK(10, 0)
> > > > +#define  PC_BUF_ACTIVE_DEPTH(n)                FIELD_PREP(PC_BUF_ACTIVE_DEPTH_MASK, (n))
> > > > +
> > > > +#define PC_SW_RESET_REG                        0x20
> > > > +#define  PC_SW_RESET_N                 BIT(0)
> > > > +#define  PC_DISP_SW_RESET_N(n)         BIT(1 + (n))
> > > > +#define  PC_FULL_RESET_N               (PC_SW_RESET_N |                \
> > > > +                                        PC_DISP_SW_RESET_N(0) |        \
> > > > +                                        PC_DISP_SW_RESET_N(1))
> > > > +
> > > > +#define PC_REG_SET                     0x4
> > > > +#define PC_REG_CLR                     0x8
> > > > +
> > > > +#define DRIVER_NAME                    "imx8qxp-pixel-combiner"
> > > > +
> > > > +enum imx8qxp_pc_pix_data_format {
> > > > +       RGB,
> > > > +       YUV444,
> > > > +       YUV422,
> > > > +       SPLIT_RGB,
> > > 
> > > YUV444, YUV422 & SPLIT_RGB are also unused, but if their values are
> > > compatible with the PC_DISP0_PIX_DATA_FORMAT macro I think keeping
> > > them around for future reference is a good idea.
> > 
> > Yes, YUV444, YUV422 & SPLIT_RGB are compatible with the
> > PC_DISP{0, 1}_PIX_DATA_FORMAT macros, so I'll keep them here.
> > 
> > Regards,
> > Liu Ying
> > 
> > > > +};
> > > > +
> > > > +struct imx8qxp_pc_channel {
> > > > +       struct drm_bridge bridge;
> > > > +       struct drm_bridge *next_bridge;
> > > > +       struct imx8qxp_pc *pc;
> > > > +       unsigned int stream_id;
> > > > +       bool is_available;
> > > > +};
> > > > +
> > > > +struct imx8qxp_pc {
> > > > +       struct device *dev;
> > > > +       struct imx8qxp_pc_channel ch[2];
> > > > +       struct clk *clk_apb;
> > > > +       void __iomem *base;
> > > > +};
> > > > +
> > > > +static inline u32 imx8qxp_pc_read(struct imx8qxp_pc *pc, unsigned int offset)
> > > > +{
> > > > +       return readl(pc->base + offset);
> > > > +}
> > > > +
> > > > +static inline void
> > > > +imx8qxp_pc_write(struct imx8qxp_pc *pc, unsigned int offset, u32 value)
> > > > +{
> > > > +       writel(value, pc->base + offset);
> > > > +}
> > > > +
> > > > +static inline void
> > > > +imx8qxp_pc_write_set(struct imx8qxp_pc *pc, unsigned int offset, u32 value)
> > > > +{
> > > > +       imx8qxp_pc_write(pc, offset + PC_REG_SET, value);
> > > > +}
> > > > +
> > > > +static inline void
> > > > +imx8qxp_pc_write_clr(struct imx8qxp_pc *pc, unsigned int offset, u32 value)
> > > > +{
> > > > +       imx8qxp_pc_write(pc, offset + PC_REG_CLR, value);
> > > > +}
> > > > +
> > > > +static enum drm_mode_status
> > > > +imx8qxp_pc_bridge_mode_valid(struct drm_bridge *bridge,
> > > > +                            const struct drm_display_info *info,
> > > > +                            const struct drm_display_mode *mode)
> > > > +{
> > > > +       if (mode->hdisplay > 2560)
> > > > +               return MODE_BAD_HVALUE;
> > > > +
> > > > +       return MODE_OK;
> > > > +}
> > > > +
> > > > +static int imx8qxp_pc_bridge_attach(struct drm_bridge *bridge,
> > > > +                                   enum drm_bridge_attach_flags flags)
> > > > +{
> > > > +       struct imx8qxp_pc_channel *ch = bridge->driver_private;
> > > > +       struct imx8qxp_pc *pc = ch->pc;
> > > > +
> > > > +       if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
> > > > +               DRM_DEV_ERROR(pc->dev,
> > > > +                             "do not support creating a drm_connector\n");
> > > > +               return -EINVAL;
> > > > +       }
> > > > +
> > > > +       if (!bridge->encoder) {
> > > > +               DRM_DEV_ERROR(pc->dev, "missing encoder\n");
> > > > +               return -ENODEV;
> > > > +       }
> > > > +
> > > > +       return drm_bridge_attach(bridge->encoder,
> > > > +                                ch->next_bridge, bridge,
> > > > +                                DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > > > +}
> > > > +
> > > > +static void
> > > > +imx8qxp_pc_bridge_mode_set(struct drm_bridge *bridge,
> > > > +                          const struct drm_display_mode *mode,
> > > > +                          const struct drm_display_mode *adjusted_mode)
> > > > +{
> > > > +       struct imx8qxp_pc_channel *ch = bridge->driver_private;
> > > > +       struct imx8qxp_pc *pc = ch->pc;
> > > > +       u32 val;
> > > > +       int ret;
> > > > +
> > > > +       ret = pm_runtime_get_sync(pc->dev);
> > > > +       if (ret < 0)
> > > > +               DRM_DEV_ERROR(pc->dev,
> > > > +                             "failed to get runtime PM sync: %d\n", ret);
> > > > +
> > > > +       ret = clk_prepare_enable(pc->clk_apb);
> > > > +       if (ret)
> > > > +               DRM_DEV_ERROR(pc->dev, "%s: failed to enable apb clock: %d\n",
> > > > +                                                               __func__,  ret);
> > > > +
> > > > +       /* HSYNC to pixel link is active low. */
> > > > +       imx8qxp_pc_write_clr(pc, PC_CTRL_REG,
> > > > +                               PC_DISP_HSYNC_POLARITY(ch->stream_id));
> > > > +
> > > > +       /* VSYNC to pixel link is active low. */
> > > > +       imx8qxp_pc_write_clr(pc, PC_CTRL_REG,
> > > > +                               PC_DISP_VSYNC_POLARITY(ch->stream_id));
> > > > +
> > > > +       /* Data enable to pixel link is active high. */
> > > > +       imx8qxp_pc_write_set(pc, PC_CTRL_REG,
> > > > +                               PC_DISP_DVALID_POLARITY(ch->stream_id));
> > > > +
> > > > +       /* Mask the first frame output which may be incomplete. */
> > > > +       imx8qxp_pc_write_set(pc, PC_CTRL_REG, PC_VSYNC_MASK_ENABLE);
> > > > +
> > > > +       /* Only support RGB currently. */
> > > > +       val = imx8qxp_pc_read(pc, PC_CTRL_REG);
> > > > +       if (ch->stream_id == 0) {
> > > > +               val &= ~PC_DISP0_PIX_DATA_FORMAT_MASK;
> > > > +               val |= PC_DISP0_PIX_DATA_FORMAT(RGB);
> > > > +       } else {
> > > > +               val &= ~PC_DISP1_PIX_DATA_FORMAT_MASK;
> > > > +               val |= PC_DISP1_PIX_DATA_FORMAT(RGB);
> > > > +       }
> > > > +       imx8qxp_pc_write(pc, PC_CTRL_REG, val);
> > > > +
> > > > +       /* Only support bypass mode currently. */
> > > > +       imx8qxp_pc_write_set(pc, PC_CTRL_REG, PC_DISP_BYPASS(ch->stream_id));
> > > > +
> > > > +       clk_disable_unprepare(pc->clk_apb);
> > > > +}
> > > > +
> > > > +static void imx8qxp_pc_bridge_atomic_disable(struct drm_bridge *bridge,
> > > > +                               struct drm_bridge_state *old_bridge_state)
> > > > +{
> > > > +       struct imx8qxp_pc_channel *ch = bridge->driver_private;
> > > > +       struct imx8qxp_pc *pc = ch->pc;
> > > > +       int ret;
> > > > +
> > > > +       ret = pm_runtime_put(pc->dev);
> > > > +       if (ret < 0)
> > > > +               DRM_DEV_ERROR(pc->dev, "failed to put runtime PM: %d\n", ret);
> > > > +}
> > > > +
> > > > +static const u32 imx8qxp_pc_bus_output_fmts[] = {
> > > > +       MEDIA_BUS_FMT_RGB888_1X36_CPADLO,
> > > > +       MEDIA_BUS_FMT_RGB666_1X36_CPADLO,
> > > > +};
> > > > +
> > > > +static bool imx8qxp_pc_bus_output_fmt_supported(u32 fmt)
> > > > +{
> > > > +       int i;
> > > > +
> > > > +       for (i = 0; i < ARRAY_SIZE(imx8qxp_pc_bus_output_fmts); i++) {
> > > > +               if (imx8qxp_pc_bus_output_fmts[i] == fmt)
> > > > +                       return true;
> > > > +       }
> > > > +
> > > > +       return false;
> > > > +}
> > > > +
> > > > +static u32 *
> > > > +imx8qxp_pc_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_pc_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;
> > > > +
> > > > +       switch (output_fmt) {
> > > > +       case MEDIA_BUS_FMT_RGB888_1X36_CPADLO:
> > > > +               input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X30_CPADLO;
> > > > +               break;
> > > > +       case MEDIA_BUS_FMT_RGB666_1X36_CPADLO:
> > > > +               input_fmts[0] = MEDIA_BUS_FMT_RGB666_1X30_CPADLO;
> > > > +               break;
> > > > +       default:
> > > > +               kfree(input_fmts);
> > > > +               input_fmts = NULL;
> > > > +               break;
> > > > +       }
> > > > +
> > > > +       return input_fmts;
> > > > +}
> > > > +
> > > > +static u32 *
> > > > +imx8qxp_pc_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_pc_bus_output_fmts);
> > > > +       return kmemdup(imx8qxp_pc_bus_output_fmts,
> > > > +                       sizeof(imx8qxp_pc_bus_output_fmts), GFP_KERNEL);
> > > > +}
> > > > +
> > > > +static const struct drm_bridge_funcs imx8qxp_pc_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,
> > > > +       .mode_valid             = imx8qxp_pc_bridge_mode_valid,
> > > > +       .attach                 = imx8qxp_pc_bridge_attach,
> > > > +       .mode_set               = imx8qxp_pc_bridge_mode_set,
> > > > +       .atomic_disable         = imx8qxp_pc_bridge_atomic_disable,
> > > > +       .atomic_get_input_bus_fmts =
> > > > +                               imx8qxp_pc_bridge_atomic_get_input_bus_fmts,
> > > > +       .atomic_get_output_bus_fmts =
> > > > +                               imx8qxp_pc_bridge_atomic_get_output_bus_fmts,
> > > > +};
> > > > +
> > > > +static int imx8qxp_pc_bridge_probe(struct platform_device *pdev)
> > > > +{
> > > > +       struct imx8qxp_pc *pc;
> > > > +       struct imx8qxp_pc_channel *ch;
> > > > +       struct device *dev = &pdev->dev;
> > > > +       struct device_node *np = dev->of_node;
> > > > +       struct device_node *child, *remote;
> > > > +       u32 i;
> > > > +       int ret;
> > > > +
> > > > +       pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
> > > > +       if (!pc)
> > > > +               return -ENOMEM;
> > > > +
> > > > +       pc->base = devm_platform_ioremap_resource(pdev, 0);
> > > > +       if (IS_ERR(pc->base))
> > > > +               return PTR_ERR(pc->base);
> > > > +
> > > > +       pc->dev = dev;
> > > > +
> > > > +       pc->clk_apb = devm_clk_get(dev, "apb");
> > > > +       if (IS_ERR(pc->clk_apb)) {
> > > > +               ret = PTR_ERR(pc->clk_apb);
> > > > +               if (ret != -EPROBE_DEFER)
> > > > +                       DRM_DEV_ERROR(dev, "failed to get apb clock: %d\n",
> > > > +                                                                       ret);
> > > > +               return ret;
> > > > +       }
> > > > +
> > > > +       platform_set_drvdata(pdev, pc);
> > > > +       pm_runtime_enable(dev);
> > > > +
> > > > +       for_each_available_child_of_node(np, child) {
> > > > +               ret = of_property_read_u32(child, "reg", &i);
> > > > +               if (ret || i > 1) {
> > > > +                       ret = -EINVAL;
> > > > +                       DRM_DEV_ERROR(dev,
> > > > +                                     "invalid channel(%u) node address\n", i);
> > > > +                       goto free_child;
> > > > +               }
> > > > +
> > > > +               ch = &pc->ch[i];
> > > > +               ch->pc = pc;
> > > > +               ch->stream_id = i;
> > > > +
> > > > +               remote = of_graph_get_remote_node(child, 1, 0);
> > > > +               if (!remote) {
> > > > +                       ret = -ENODEV;
> > > > +                       DRM_DEV_ERROR(dev,
> > > > +                           "channel%u failed to get port1's remote node: %d\n",
> > > > +                                                                       i, ret);
> > > > +                       goto free_child;
> > > > +               }
> > > > +
> > > > +               ch->next_bridge = of_drm_find_bridge(remote);
> > > > +               if (!ch->next_bridge) {
> > > > +                       of_node_put(remote);
> > > > +                       ret = -EPROBE_DEFER;
> > > > +                       DRM_DEV_DEBUG_DRIVER(dev,
> > > > +                               "channel%u failed to find next bridge: %d\n",
> > > > +                                                                       i, ret);
> > > > +                       goto free_child;
> > > > +               }
> > > > +
> > > > +               of_node_put(remote);
> > > > +
> > > > +               ch->bridge.driver_private = ch;
> > > > +               ch->bridge.funcs = &imx8qxp_pc_bridge_funcs;
> > > > +               ch->bridge.of_node = child;
> > > > +               ch->is_available = true;
> > > > +
> > > > +               drm_bridge_add(&ch->bridge);
> > > > +       }
> > > > +
> > > > +       return 0;
> > > > +
> > > > +free_child:
> > > > +       of_node_put(child);
> > > > +
> > > > +       if (i == 1 && pc->ch[0].next_bridge)
> > > > +               drm_bridge_remove(&pc->ch[0].bridge);
> > > > +
> > > > +       pm_runtime_disable(dev);
> > > > +       return ret;
> > > > +}
> > > > +
> > > > +static int imx8qxp_pc_bridge_remove(struct platform_device *pdev)
> > > > +{
> > > > +       struct imx8qxp_pc *pc = platform_get_drvdata(pdev);
> > > > +       struct imx8qxp_pc_channel *ch;
> > > > +       int i;
> > > > +
> > > > +       for (i = 0; i < 2; i++) {
> > > > +               ch = &pc->ch[i];
> > > > +
> > > > +               if (!ch->is_available)
> > > > +                       continue;
> > > > +
> > > > +               drm_bridge_remove(&ch->bridge);
> > > > +               ch->is_available = false;
> > > > +       }
> > > > +
> > > > +       pm_runtime_disable(&pdev->dev);
> > > > +
> > > > +       return 0;
> > > > +}
> > > > +
> > > > +static int __maybe_unused imx8qxp_pc_runtime_suspend(struct device *dev)
> > > > +{
> > > > +       struct platform_device *pdev = to_platform_device(dev);
> > > > +       struct imx8qxp_pc *pc = platform_get_drvdata(pdev);
> > > > +       int ret;
> > > > +
> > > > +       ret = clk_prepare_enable(pc->clk_apb);
> > > > +       if (ret)
> > > > +               DRM_DEV_ERROR(pc->dev, "%s: failed to enable apb clock: %d\n",
> > > > +                                                               __func__,  ret);
> > > > +
> > > > +       /* Disable pixel combiner by full reset. */
> > > > +       imx8qxp_pc_write_clr(pc, PC_SW_RESET_REG, PC_FULL_RESET_N);
> > > > +
> > > > +       clk_disable_unprepare(pc->clk_apb);
> > > > +
> > > > +       /* Ensure the reset takes effect. */
> > > > +       usleep_range(10, 20);
> > > > +
> > > > +       return ret;
> > > > +}
> > > > +
> > > > +static int __maybe_unused imx8qxp_pc_runtime_resume(struct device *dev)
> > > > +{
> > > > +       struct platform_device *pdev = to_platform_device(dev);
> > > > +       struct imx8qxp_pc *pc = platform_get_drvdata(pdev);
> > > > +       int ret;
> > > > +
> > > > +       ret = clk_prepare_enable(pc->clk_apb);
> > > > +       if (ret) {
> > > > +               DRM_DEV_ERROR(pc->dev, "%s: failed to enable apb clock: %d\n",
> > > > +                                                               __func__, ret);
> > > > +               return ret;
> > > > +       }
> > > > +
> > > > +       /* out of reset */
> > > > +       imx8qxp_pc_write_set(pc, PC_SW_RESET_REG, PC_FULL_RESET_N);
> > > > +
> > > > +       clk_disable_unprepare(pc->clk_apb);
> > > > +
> > > > +       return ret;
> > > > +}
> > > > +
> > > > +static const struct dev_pm_ops imx8qxp_pc_pm_ops = {
> > > > +       SET_RUNTIME_PM_OPS(imx8qxp_pc_runtime_suspend,
> > > > +                          imx8qxp_pc_runtime_resume, NULL)
> > > > +};
> > > > +
> > > > +static const struct of_device_id imx8qxp_pc_dt_ids[] = {
> > > > +       { .compatible = "fsl,imx8qm-pixel-combiner", },
> > > > +       { .compatible = "fsl,imx8qxp-pixel-combiner", },
> > > > +       { /* sentinel */ }
> > > > +};
> > > > +MODULE_DEVICE_TABLE(of, imx8qxp_pc_dt_ids);
> > > > +
> > > > +static struct platform_driver imx8qxp_pc_bridge_driver = {
> > > > +       .probe  = imx8qxp_pc_bridge_probe,
> > > > +       .remove = imx8qxp_pc_bridge_remove,
> > > > +       .driver = {
> > > > +               .pm = &imx8qxp_pc_pm_ops,
> > > > +               .name = DRIVER_NAME,
> > > > +               .of_match_table = imx8qxp_pc_dt_ids,
> > > > +       },
> > > > +};
> > > > +module_platform_driver(imx8qxp_pc_bridge_driver);
> > > > +
> > > > +MODULE_DESCRIPTION("i.MX8QM/QXP pixel combiner bridge driver");
> > > > +MODULE_AUTHOR("Liu Ying <victor.liu@nxp.com>");
> > > > +MODULE_LICENSE("GPL v2");
> > > > +MODULE_ALIAS("platform:" DRIVER_NAME);
> > > > --
> > > > 2.7.4
> > > >