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    SubjectRe: [PATCH v4 3/9] drm: rcar-du: Add support for CMM
    Hi Jacopo,

    On Thu, Oct 10, 2019 at 07:46:28PM +0200, Jacopo Mondi wrote:
    > On Thu, Sep 19, 2019 at 01:55:35AM +0300, Laurent Pinchart wrote:
    > > On Fri, Sep 06, 2019 at 03:54:30PM +0200, Jacopo Mondi wrote:
    > >> Add a driver for the R-Car Display Unit Color Correction Module.
    > >>
    > >> In most of Gen3 SoCs, each DU output channel is provided with a CMM unit
    > >> to perform image enhancement and color correction.
    > >>
    > >> Add support for CMM through a driver that supports configuration of
    > >> the 1-dimensional LUT table. More advanced CMM feature will be
    > >> implemented on top of this basic one.
    > >>
    > >> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
    > >> ---
    > >> drivers/gpu/drm/rcar-du/Kconfig | 7 +
    > >> drivers/gpu/drm/rcar-du/Makefile | 1 +
    > >> drivers/gpu/drm/rcar-du/rcar_cmm.c | 251 +++++++++++++++++++++++++++++
    > >> drivers/gpu/drm/rcar-du/rcar_cmm.h | 61 +++++++
    > >> 4 files changed, 320 insertions(+)
    > >> create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.c
    > >> create mode 100644 drivers/gpu/drm/rcar-du/rcar_cmm.h
    > >>
    > >> diff --git a/drivers/gpu/drm/rcar-du/Kconfig b/drivers/gpu/drm/rcar-du/Kconfig
    > >> index 1529849e217e..539d232790d1 100644
    > >> --- a/drivers/gpu/drm/rcar-du/Kconfig
    > >> +++ b/drivers/gpu/drm/rcar-du/Kconfig
    > >> @@ -13,6 +13,13 @@ config DRM_RCAR_DU
    > >> Choose this option if you have an R-Car chipset.
    > >> If M is selected the module will be called rcar-du-drm.
    > >>
    > >> +config DRM_RCAR_CMM
    > >> + bool "R-Car DU Color Management Module (CMM) Support"
    > >> + depends on DRM && OF
    > >> + depends on DRM_RCAR_DU
    > >> + help
    > >> + Enable support for R-Car Color Management Module (CMM).
    > >> +
    > >> config DRM_RCAR_DW_HDMI
    > >> tristate "R-Car DU Gen3 HDMI Encoder Support"
    > >> depends on DRM && OF
    > >> diff --git a/drivers/gpu/drm/rcar-du/Makefile b/drivers/gpu/drm/rcar-du/Makefile
    > >> index 6c2ed9c46467..4d1187ccc3e5 100644
    > >> --- a/drivers/gpu/drm/rcar-du/Makefile
    > >> +++ b/drivers/gpu/drm/rcar-du/Makefile
    > >> @@ -15,6 +15,7 @@ rcar-du-drm-$(CONFIG_DRM_RCAR_LVDS) += rcar_du_of.o \
    > >> rcar-du-drm-$(CONFIG_DRM_RCAR_VSP) += rcar_du_vsp.o
    > >> rcar-du-drm-$(CONFIG_DRM_RCAR_WRITEBACK) += rcar_du_writeback.o
    > >>
    > >> +obj-$(CONFIG_DRM_RCAR_CMM) += rcar_cmm.o
    > >> obj-$(CONFIG_DRM_RCAR_DU) += rcar-du-drm.o
    > >> obj-$(CONFIG_DRM_RCAR_DW_HDMI) += rcar_dw_hdmi.o
    > >> obj-$(CONFIG_DRM_RCAR_LVDS) += rcar_lvds.o
    > >> diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.c b/drivers/gpu/drm/rcar-du/rcar_cmm.c
    > >> new file mode 100644
    > >> index 000000000000..3cacdc4474c7
    > >> --- /dev/null
    > >> +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.c
    > >> @@ -0,0 +1,251 @@
    > >> +// SPDX-License-Identifier: GPL-2.0+
    > >> +/*
    > >> + * rcar_cmm.c -- R-Car Display Unit Color Management Module
    > >> + *
    > >> + * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@jmondi.org>
    > >> + */
    > >> +
    > >> +#include <linux/io.h>
    > >> +#include <linux/module.h>
    > >> +#include <linux/of.h>
    > >> +#include <linux/platform_device.h>
    > >> +#include <linux/pm_runtime.h>
    > >> +
    > >> +#include <drm/drm_color_mgmt.h>
    > >> +
    > >> +#include "rcar_cmm.h"
    > >> +
    > >> +#define CM2_LUT_CTRL 0x0000
    > >> +#define CM2_LUT_CTRL_LUT_EN BIT(0)
    > >> +#define CM2_LUT_TBL_BASE 0x0600
    > >> +#define CM2_LUT_TBL(__i) (CM2_LUT_TBL_BASE + (__i) * 4)
    > >> +
    > >> +struct rcar_cmm {
    > >> + void __iomem *base;
    > >> + bool enabled;
    > >> +
    > >> + /*
    > >> + * @lut: 1D-LUT status
    > >> + * @lut.enabled: 1D-LUT enabled flag
    > >> + * @lut.table: Table of 1D-LUT entries scaled to hardware
    > >> + * precision (8-bits per color component)
    > >> + */
    > >> + struct {
    > >> + bool enabled;
    > >> + u32 table[CM2_LUT_SIZE];
    > >> + } lut;
    > >> +};
    > >> +
    > >> +static inline int rcar_cmm_read(struct rcar_cmm *rcmm, u32 reg)
    > >> +{
    > >> + return ioread32(rcmm->base + reg);
    > >> +}
    > >> +
    > >> +static inline void rcar_cmm_write(struct rcar_cmm *rcmm, u32 reg, u32 data)
    > >> +{
    > >> + iowrite32(data, rcmm->base + reg);
    > >> +}
    > >> +
    > >> +/*
    > >> + * rcar_cmm_lut_extract() - Scale down to hardware precision the DRM LUT table
    > >> + * entries and store them.
    > >
    > > "Scale the DRM LUT table entries to hardware precision and store them."
    > >
    > >> + * @rcmm: Pointer to the CMM device
    > >> + * @drm_lut: Pointer to the DRM LUT table
    > >> + */
    > >> +static void rcar_cmm_lut_extract(struct rcar_cmm *rcmm,
    > >> + const struct drm_color_lut *drm_lut)
    > >> +{
    > >> + unsigned int i;
    > >> +
    > >> + for (i = 0; i < CM2_LUT_SIZE; ++i) {
    > >> + const struct drm_color_lut *lut = &drm_lut[i];
    > >> +
    > >> + rcmm->lut.table[i] = drm_color_lut_extract(lut->red, 8) << 16
    > >> + | drm_color_lut_extract(lut->green, 8) << 8
    > >> + | drm_color_lut_extract(lut->blue, 8);
    > >> + }
    > >> +}
    > >> +
    > >> +/*
    > >> + * rcar_cmm_lut_write() - Write to hardware the LUT table entries from the
    > >> + * local table.
    > >
    > > "Write the LUT table entries from the local table to the hardware."
    > >
    > >> + * @rcmm: Pointer to the CMM device
    > >> + */
    > >> +static void rcar_cmm_lut_write(struct rcar_cmm *rcmm)
    > >> +{
    > >> + unsigned int i;
    > >> +
    > >> + for (i = 0; i < CM2_LUT_SIZE; ++i)
    > >> + rcar_cmm_write(rcmm, CM2_LUT_TBL(i), rcmm->lut.table[i]);
    > >> +}
    > >> +
    > >> +/*
    > >> + * rcar_cmm_setup() - Configure the CMM unit.
    > >> + * @pdev: The platform device associated with the CMM instance
    > >> + * @config: The CRTC-provided configuration.
    > >> + *
    > >> + * Configure the CMM unit with the CRTC-provided configuration.
    > >> + * Currently enabling, disabling and programming of the 1-D LUT unit is
    > >> + * supported.
    > >> + */
    > >> +int rcar_cmm_setup(struct platform_device *pdev,
    > >> + const struct rcar_cmm_config *config)
    > >> +{
    > >> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
    > >> +
    > >> + /*
    > >> + * As rcar_cmm_setup() is called by atomic commit tail helper, it might
    > >> + * be called when the CMM is disabled. As we can't program the hardware
    > >> + * in that case, store the configuration internally and apply it when
    > >> + * the CMM will be enabled by the CRTC through rcar_cmm_enable().
    > >> + */
    > >> + if (!rcmm->enabled) {
    > >> + if (!config->lut.enable)
    > >> + return 0;
    > >> +
    > >> + rcar_cmm_lut_extract(rcmm, config->lut.table);
    > >> + rcmm->lut.enabled = true;
    > >> +
    > >> + return 0;
    > >> + }
    > >> +
    > >> + /* Stop LUT operations if requested. */
    > >> + if (!config->lut.enable) {
    > >> + if (rcmm->lut.enabled) {
    > >> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
    > >> + rcmm->lut.enabled = false;
    > >> + }
    > >> +
    > >> + return 0;
    > >> + }
    > >> +
    > >> + /*
    > >> + * Enable LUT and program the new gamma table values.
    > >> + *
    > >> + * FIXME: In order to have stable operations it is required to first
    > >> + * enable the 1D-LUT and then program its table entries. This seems to
    > >> + * contradict what the chip manual reports, and will have to be
    > >> + * reconsidered when implementing support for double buffering.
    > >> + */
    > >> + if (!rcmm->lut.enabled) {
    > >> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_LUT_EN);
    > >> + rcmm->lut.enabled = true;
    > >> + }
    > >> +
    > >> + rcar_cmm_lut_extract(rcmm, config->lut.table);
    > >> + rcar_cmm_lut_write(rcmm);
    > >> +
    > >> + return 0;
    > >> +}
    > >> +EXPORT_SYMBOL_GPL(rcar_cmm_setup);
    > >> +
    > >> +/*
    > >> + * rcar_cmm_enable() - Enable the CMM unit.
    > >> + * @pdev: The platform device associated with the CMM instance
    > >> + *
    > >> + * Enable the CMM unit by enabling the parent clock and enabling the CMM
    > >> + * components, such as 1-D LUT, if requested.
    > >> + */
    > >> +int rcar_cmm_enable(struct platform_device *pdev)
    > >> +{
    > >> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
    > >> + int ret;
    > >> +
    > >> + ret = pm_runtime_get_sync(&pdev->dev);
    > >> + if (ret < 0)
    > >> + return ret;
    > >> +
    > >> + /* Apply the LUT table values saved at rcar_cmm_setup() time. */
    > >> + if (rcmm->lut.enabled) {
    > >> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_LUT_EN);
    > >> + rcar_cmm_lut_write(rcmm);
    > >> + }
    > >> +
    > >> + rcmm->enabled = true;
    > >> +
    > >> + return 0;
    > >> +}
    > >> +EXPORT_SYMBOL_GPL(rcar_cmm_enable);
    > >> +
    > >> +/*
    > >> + * rcar_cmm_disable() - Disable the CMM unit.
    > >> + * @pdev: The platform device associated with the CMM instance
    > >> + *
    > >> + * Disable the CMM unit by stopping the parent clock.
    > >> + */
    > >> +void rcar_cmm_disable(struct platform_device *pdev)
    > >> +{
    > >> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
    > >> +
    > >> + rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
    > >> +
    > >> + pm_runtime_put(&pdev->dev);
    > >> +
    > >> + rcmm->lut.enabled = false;
    > >> + rcmm->enabled = false;
    > >> +}
    > >> +EXPORT_SYMBOL_GPL(rcar_cmm_disable);
    > >> +
    > >> +/*
    > >> + * rcar_cmm_init() - Make sure the CMM has probed.
    > >
    > > I would document this as "Intialize the CMM" to match the function name.
    > > We may add more initialization in the future.
    > >
    > >> + * @pdev: The platform device associated with the CMM instance
    > >> + *
    > >> + * Return: 0 if the CMM has probed, -EPROBE_DEFER otherwise
    > >
    > > 0 on success, -EPROBE_DEFER is the CMM isn't availablet yet
    > >
    >
    > Just to note I've take Kieran's suggestion in to return -ENODEV when
    > the CMM config option is not set.
    >
    > >> + */
    > >> +int rcar_cmm_init(struct platform_device *pdev)
    > >> +{
    > >> + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
    > >> +
    > >> + if (!rcmm)
    > >> + return -EPROBE_DEFER;
    > >> +
    > >> + return 0;
    > >> +}
    > >> +EXPORT_SYMBOL_GPL(rcar_cmm_init);
    > >> +
    > >> +static int rcar_cmm_probe(struct platform_device *pdev)
    > >> +{
    > >> + struct rcar_cmm *rcmm;
    > >> +
    > >> + rcmm = devm_kzalloc(&pdev->dev, sizeof(*rcmm), GFP_KERNEL);
    > >> + if (!rcmm)
    > >> + return -ENOMEM;
    > >> + platform_set_drvdata(pdev, rcmm);
    > >> +
    > >> + rcmm->base = devm_platform_ioremap_resource(pdev, 0);
    > >> + if (IS_ERR(rcmm->base))
    > >> + return PTR_ERR(rcmm->base);
    > >> +
    > >> + pm_runtime_enable(&pdev->dev);
    > >> +
    > >> + return 0;
    > >> +}
    > >> +
    > >> +static int rcar_cmm_remove(struct platform_device *pdev)
    > >> +{
    > >> + pm_runtime_disable(&pdev->dev);
    > >> +
    > >> + return 0;
    > >> +}
    > >> +
    > >> +static const struct of_device_id rcar_cmm_of_table[] = {
    > >> + { .compatible = "renesas,rcar-gen3-cmm", },
    > >> + { .compatible = "renesas,rcar-gen2-cmm", },
    > >> + { },
    > >> +};
    > >> +MODULE_DEVICE_TABLE(of, rcar_cmm_of_table);
    > >> +
    > >> +static struct platform_driver rcar_cmm_platform_driver = {
    > >> + .probe = rcar_cmm_probe,
    > >> + .remove = rcar_cmm_remove,
    > >> + .driver = {
    > >> + .name = "rcar-cmm",
    > >> + .of_match_table = rcar_cmm_of_table,
    > >> + },
    > >> +};
    > >> +
    > >> +module_platform_driver(rcar_cmm_platform_driver);
    > >> +
    > >> +MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
    > >> +MODULE_DESCRIPTION("Renesas R-Car CMM Driver");
    > >> +MODULE_LICENSE("GPL v2");
    > >> diff --git a/drivers/gpu/drm/rcar-du/rcar_cmm.h b/drivers/gpu/drm/rcar-du/rcar_cmm.h
    > >> new file mode 100644
    > >> index 000000000000..15a2c874b6a6
    > >> --- /dev/null
    > >> +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.h
    > >> @@ -0,0 +1,61 @@
    > >> +/* SPDX-License-Identifier: GPL-2.0+ */
    > >> +/*
    > >> + * rcar_cmm.h -- R-Car Display Unit Color Management Module
    > >> + *
    > >> + * Copyright (C) 2019 Jacopo Mondi <jacopo+renesas@jmondi.org>
    > >> + */
    > >> +
    > >> +#ifndef __RCAR_CMM_H__
    > >> +#define __RCAR_CMM_H__
    > >> +
    > >> +#define CM2_LUT_SIZE 256
    > >> +
    > >> +struct drm_color_lut;
    > >> +struct platform_device;
    > >> +
    > >> +/**
    > >> + * struct rcar_cmm_config - CMM configuration
    > >> + *
    > >> + * @lut: 1D-LUT configuration
    > >> + * @lut.enable: 1D-LUT enable flag
    > >> + * @lut.table: 1D-LUT table entries. Might be set to NULL when the CMM has to
    > >> + * be re-enabled but not re=programmed.
    > >
    > > s/re=programmed/re-programmed/
    > >
    > > As discussed offline this can't really happen as far as I can tell.
    > > However, it will still be useful when we'll add CLU support, as then a
    > > CLU reprogramming without a LUT reprogramming could happen.
    >
    > How are we going to program CLU ? Using which DRM property ?
    > I had a look at 'ctm', but it does not seems to apply, as it only
    > provides 9 64bits entries (why 9??)
    > https://elixir.bootlin.com/linux/latest/source/include/uapi/drm/drm_mode.h#L623
    >
    > The CLU is programmed with pairs of 32bits entries, assembled using
    > 8 bit data/addresses for each color components. Considering the LUT
    > entries have 16 bits per color components, we could re-use those, but
    > seems a bit of an abuse to me. Is there somethig more trivial I am
    > missing ?

    You're not missing anything, we'll have to create a new property for
    this. The CLU is a 17x17x17 matrix of 32-bit values, that's what we'll
    have to pass.

    > Anyway, for now I think you are right, and if the 'crtc->state->gamma_lut'
    > field is set, then the table (provided it's of the right size) cannot be
    > NULL.
    >
    > Disabling the CMM with:
    > req.add(crtc, {
    > { "GAMMA_LUT", 0 },
    > });
    >
    > results in 'crtc->state->gamma_lut' being not set, and this is already
    > handled by setting to false the rcar_cmm_config.lut.enable flag in
    > rcar_du_atomic_commit_update_cmm() so I would rather drop the table ==
    > NULL case from documentation and re-think about it once we handle CLU.
    >
    > > I think we should make the documentation a bit clearer:
    > >
    > > "1D-LUT table entries. Only valid when lut.enable is true, shall be NULL
    > > otherwise. When non-NULL, the LUT table will be programmed with the new
    > > values. Otherwise the LUT table will retain its previously programmed
    > > values."
    > >
    > > This being said, the code in rcar_cmm_setup() will crash if table is
    > > NULL. I would either drop the option of table being NULL (and thus
    > > update the documentation here) if you don't need this yet in the DU
    > > driver, or fix rcar_cmm_setup(). You've posted enough versions of this
    > > series in my opinion, so please pick the easiest option, and we'll
    > > rework the code when adding CLU support anyway.
    >
    > Unfortunately I would love to take your tag in and being done with
    > this, but considering Sean's advices on Ezequiel's series, I think
    > I'll now need to move CMM handling to crtc's begin/enable as well, so
    > another review round will likely be required.
    >
    > > With those small issues fixes,
    > >
    > > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
    > >
    > >> + */
    > >> +struct rcar_cmm_config {
    > >> + struct {
    > >> + bool enable;
    > >> + struct drm_color_lut *table;
    > >> + } lut;
    > >> +};
    > >> +
    > >> +#if IS_ENABLED(CONFIG_DRM_RCAR_CMM)
    > >> +int rcar_cmm_init(struct platform_device *pdev);
    > >> +
    > >> +int rcar_cmm_enable(struct platform_device *pdev);
    > >> +void rcar_cmm_disable(struct platform_device *pdev);
    > >> +
    > >> +int rcar_cmm_setup(struct platform_device *pdev,
    > >> + const struct rcar_cmm_config *config);
    > >> +#else
    > >> +static inline int rcar_cmm_init(struct platform_device *pdev)
    > >> +{
    > >> + return 0;
    > >> +}
    > >> +
    > >> +static inline int rcar_cmm_enable(struct platform_device *pdev)
    > >> +{
    > >> + return 0;
    > >> +}
    > >> +
    > >> +static inline void rcar_cmm_disable(struct platform_device *pdev)
    > >> +{
    > >> +}
    > >> +
    > >> +static int rcar_cmm_setup(struct platform_device *pdev,
    > >> + const struct rcar_cmm_config *config)
    > >> +{
    > >> + return 0;
    > >> +}
    > >> +#endif /* IS_ENABLED(CONFIG_DRM_RCAR_CMM) */
    > >> +
    > >> +#endif /* __RCAR_CMM_H__ */

    --
    Regards,

    Laurent Pinchart

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