by Geert Uytterhoeven

[permalink] [raw]

Subject: Re: [PATCH v4 9/9] arm64: dts: renesas: Add CMM units to Gen3 SoCs

Hi Kieran, Jacopo,

On Wed, Sep 11, 2019 at 8:16 PM Kieran Bingham
<[email protected]> wrote:
> On 06/09/2019 14:54, Jacopo Mondi wrote:
> > Add CMM units to Renesas R-Car Gen3 SoC that support it, and reference them
> > from the Display Unit they are connected to.
> >
> > Sort the 'vsps' and 'renesas,cmm' entries in the DU unit consistently
> > in all the involved DTS.
>
> I think if you chose the ordering in the r8a7795, then you only have to
> adjust/correct the ordering in the r8a7796 and r8a77965 ...
>
> Especially as you haven't changed the ordering of r8a77970, and r8a77980
> which have the status after the vsps entry.
>
>
> >
> > Signed-off-by: Jacopo Mondi <[email protected]>

> > --- a/arch/arm64/boot/dts/renesas/r8a7795.dtsi
> > +++ b/arch/arm64/boot/dts/renesas/r8a7795.dtsi

> > @@ -3142,9 +3178,11 @@
> > <&cpg CPG_MOD 722>,
> > <&cpg CPG_MOD 721>;
> > clock-names = "du.0", "du.1", "du.2", "du.3";
> > - vsps = <&vspd0 0>, <&vspd1 0>, <&vspd2 0>, <&vspd0 1>;
> > status = "disabled";
>
> I'm not sure the vsps should be below the status = disabled line.
>
> I'd have this as:
>
> clock-names...
> vsps...
> renesas,cmms...
> <blank line>
> status...
> <blank line>
> ports...

Indeed.

And better write "ports { ... }", so it's clear this is a subnode.

>
> >
> > + vsps = <&vspd0 0>, <&vspd1 0>, <&vspd2 0>, <&vspd0 1>;

And the above will become "renesas,vsps", needing another reordering?

> > + renesas,cmms = <&cmm0 &cmm1 &cmm2 &cmm3>;
>
> I think these should be separated by comma's to show they are separate
> references, or references to separate phandles or such.

Yep, looks better, and makes the grouping clear.

> The only precedence I could find was in pmu_a53:
>
> interrupt-affinity = <&a53_0>, <&a53_1>, <&a53_2>, <&a53_3>;

That's because most other phandle stuff has #<foo>-cells as non-zero.

We do have

clocks = ... <&audio_clk_a>, <&audio_clk_b>, <&audio_clk_c>;

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

2019-09-12 08:00:10

by jacopo mondi

[permalink] [raw]

Subject: Re: [PATCH v4 3/9] drm: rcar-du: Add support for CMM

Hi Kiernan,
thanks for review

On Wed, Sep 11, 2019 at 04:54:58PM +0100, Kieran Bingham wrote:
> Hi Jacopo,
>
> <This time replying to the mail with ML's included Doh!>
>
> On 06/09/2019 14:43, 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
>
> s/feature/features/
>
> > implemented on top of this basic one.
>
> s/basic/initial/
>
> >
> > Signed-off-by: Jacopo Mondi <[email protected]>
> > ---
> > 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 <[email protected]>
> > + */
> > +
> > +#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)
>
> I'd have a new line here
>
> > +#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.
> > + * @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;
>
> I think you're missing the following here:
>
> if (!drm_lut)
> return;
>
> You mention below that drm_lut could be passed in as NULL, which would
> cause a segfault here otherwise.
>

Thanks for spotting, but I should have removed that comment, as I have
killed that case in rcar_du_atomic_commit_update_cmm() in patch 8/9,
as from my testing it seems it is not possible to provide from
userspace a non populated LUT table to just re-enable the CMM.

So we're fine here.

>
> > +
> > + 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.
> > + * @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.
>
> I don't think CRTC-provided should be hyphenated like that.
> Perhaps just:
> "The colour management configuration".
>
> As I don't think who provides the configuration is relevant to the
> actual call.
>

I have no idea. I've been bought into this by the comment

"CRTC-provided" is a compound adjective, qualifying the noun
"configuration". It thus needs a hyphen.

I'm happy to remove it for a simpler version.

Thanks
j

> > + * Configure the CMM unit with the CRTC-provided configuration.
>
> s/CRTC-provided/given/
>
> > + * 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.
> > + * @pdev: The platform device associated with the CMM instance
> > + *
> > + * Return: 0 if the CMM has probed, -EPROBE_DEFER otherwise
> > + */
> > +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 <[email protected]>");
> > +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 <[email protected]>
> > + */
> > +
> > +#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.
>
> So lut.table can be NULL ... See comment at rcar_cmm_lut_extract()
>
> > + */
> > +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__ */
> >
>

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2019-09-12 08:08:31

Hi Laurent,

On Thu, Sep 19, 2019 at 01:55:35AM +0300, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> 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 <[email protected]>
> > ---
> > 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 <[email protected]>
> > + */
> > +
> > +#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 <[email protected]>");
> > +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 <[email protected]>
> > + */
> > +
> > +#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 ?

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 <[email protected]>
>
> > + */
> > +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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2019-10-15 01:52:29

by Laurent Pinchart

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Subject: Re: [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 <[email protected]>
> >> ---
> >> 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 <[email protected]>
> >> + */
> >> +
> >> +#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 <[email protected]>");
> >> +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 <[email protected]>
> >> + */
> >> +
> >> +#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 <[email protected]>
> >
> >> + */
> >> +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