lkml.org 
[lkml]   [2019]   [Jun]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 14/20] drm: rcar-du: Add support for CMM
Hi Jacopo,

On Fri, Jun 07, 2019 at 02:35:40PM +0300, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Thu, Jun 06, 2019 at 04:22:14PM +0200, Jacopo Mondi wrote:
> > Add a driver for the R-Car Display Unit Color Correction Module.
> >
> > Each DU output channel is provided with a CMM unit to perform image
> > enhancement and color correction.
>
> I would say "On most Gen3 SoCs, each DU ..." as V3* SoCs have no CMM.
>
> >
> > Add support for CMM through a driver that supports configuration of
> > the 1-dimensional LUT table. More advanced CMM feature could be
> > implemented on top of this basic one.
>
> s/could be/will be/ ? :-)
>
> >
> > 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 | 197 +++++++++++++++++++++++++++++
> > drivers/gpu/drm/rcar-du/rcar_cmm.h | 38 ++++++
> > 4 files changed, 243 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..5d9d917b91f4
> > --- /dev/null
> > +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.c
> > @@ -0,0 +1,197 @@
> > +// 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/clk.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <drm/drm_atomic.h>
> > +
> > +#include "rcar_cmm.h"
> > +
> > +#define CM2_LUT_CTRL 0x00
>
> I would write all register addresses with 3 (or 4) digits.
>
> > +#define CM2_LUT_CTRL_EN BIT(0)
> > +#define CM2_LUT_TBLA 0x600
>
> I would define this as
>
> #define CM2_LUT_TBLA(n) (0x600 + (n) * 4)
>
> > +
> > +struct rcar_cmm {
> > + struct clk *clk;
> > + void __iomem *base;
> > + bool enabled;
> > +
> > + /* LUT table scratch buffer. */
> > + struct {
> > + bool restore;
> > + unsigned int size;
> > + uint32_t table[CMM_GAMMA_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);
> > +}
> > +
> > +int rcar_cmm_setup(struct platform_device *pdev, struct rcar_cmm_config *config)
>
> Please document the functions exposed to the DU driver. It's hard to
> understand the setup vs. enable/disable split by just reading this
> driver.
>
> > +{
> > + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> > + unsigned int i;
> > +
> > + if (config->lut.size > CMM_GAMMA_LUT_SIZE)
> > + return -EINVAL;
> > +
> > + /*
> > + * As cmm_setup is called by atomic commit tail helper, it might be
> > + * called before the enabling the CRTC (which calls cmm_enable()).
> > + *
> > + * Store the LUT table entries in the scratch buffer to be later
> > + * programmed at enable time.
> > + */
> > + if (!rcmm->enabled) {
> > + if (!config->lut.enable)
> > + return 0;
> > +
> > + for (i = 0; i < config->lut.size; ++i) {
> > + struct drm_color_lut *lut = &config->lut.table[i];
> > +
> > + rcmm->lut.table[i] = (lut->red & 0xff) << 16 |
> > + (lut->green & 0xff) << 8 |
> > + (lut->blue & 0xff);
> > + }
> > +
> > + rcmm->lut.restore = true;
> > + rcmm->lut.size = config->lut.size;
> > +
> > + return 0;
> > + }
> > +
> > + if (rcar_cmm_read(rcmm, CM2_LUT_CTRL) & CM2_LUT_CTRL_EN &&
> > + !config->lut.enable) {
> > + rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
> > + return 0;
> > + }
> > +
> > + /* Enable LUT and program the new gamma table values. */
> > + rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_EN);
>
> Shouldn't you write the LUT contents before enabling it (same below) ?
>
> > + for (i = 0; i < config->lut.size; ++i) {
> > + struct drm_color_lut *lut = &config->lut.table[i];
> > + u32 val = (lut->red & 0xff) << 16 | (lut->green & 0xff) << 8 |
> > + (lut->blue & 0xff);
>
> Do you need to recompute the value, can't you use rcmm->lut.table ?
>
> > +
> > + rcar_cmm_write(rcmm, CM2_LUT_TBLA + i * 4, val);
> > + }
> > +
> > + return 0;
> > +}
>
> You need to export this and the next two functions.
>
> > +
> > +int rcar_cmm_enable(struct platform_device *pdev)
> > +{
> > + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> > + unsigned int i;
> > + int ret;
> > +
> > + if (rcmm->enabled)
> > + return 0;
>
> Can this happen without a bug in the caller ? If it can, and assuming
> the caller balances the enable and disable calls, you will have
> unbalanced clk_prepare_enable() and clk_disable_unprepare() calls.
>
> > +
> > + ret = clk_prepare_enable(rcmm->clk);
> > + if (ret)
> > + return ret;
>
> Could you use pm_runtime_get_sync() instead ?
>
> > +
> > + /* Apply the LUT table values saved at cmm_setup time. */
> > + if (rcmm->lut.restore) {
> > + rcar_cmm_write(rcmm, CM2_LUT_CTRL, CM2_LUT_CTRL_EN);
> > + for (i = 0; i < rcmm->lut.size; ++i)
> > + rcar_cmm_write(rcmm, CM2_LUT_TBLA + i * 4,
> > + rcmm->lut.table[i]);
> > +
> > + rcmm->lut.restore = false;
> > + rcmm->lut.size = 0;
> > + }
> > +
> > + rcmm->enabled = true;
> > +
> > + return 0;
> > +}
> > +
> > +void rcar_cmm_disable(struct platform_device *pdev)
> > +{
> > + struct rcar_cmm *rcmm = platform_get_drvdata(pdev);
> > +
> > + rcar_cmm_write(rcmm, CM2_LUT_CTRL, 0);
> > +
> > + clk_disable_unprepare(rcmm->clk);
> > +
> > + rcmm->lut.restore = false;
> > + rcmm->lut.size = 0;
> > + rcmm->enabled = false;
> > +}
> > +
> > +static int rcar_cmm_probe(struct platform_device *pdev)
> > +{
> > + struct rcar_cmm *rcmm;
> > + struct resource *res;
> > + resource_size_t size;
> > +
> > + rcmm = devm_kzalloc(&pdev->dev, sizeof(*rcmm), GFP_KERNEL);
> > + if (!rcmm)
> > + return -ENOMEM;
> > +
> > + platform_set_drvdata(pdev, rcmm);
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + size = resource_size(res);
> > + if (!devm_request_mem_region(&pdev->dev, res->start, size,
> > + dev_name(&pdev->dev))) {
> > + dev_err(&pdev->dev,
> > + "can't request region for resource %pR\n", res);
> > + return -EBUSY;
> > + }
> > +
> > + rcmm->base = devm_ioremap_nocache(&pdev->dev, res->start, size);
> > + if (IS_ERR(rcmm->base))
> > + return PTR_ERR(rcmm->base);
>
> Anything wrong with devm_ioremap_resource() ?
>
> > +
> > + rcmm->clk = devm_clk_get(&pdev->dev, NULL);
> > + if (IS_ERR(rcmm->clk)) {
> > + dev_err(&pdev->dev, "Failed to get CMM clock");
> > + return PTR_ERR(rcmm->clk);
> > + }
> > +
> > + rcmm->lut.restore = false;
> > + rcmm->lut.size = 0;
> > + rcmm->enabled = false;
>
> As you allocate memory with kzalloc() you could skip this.
>
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id rcar_cmm_of_table[] = {
> > + { .compatible = "renesas,cmm-gen3" },
> > + { .compatible = "renesas,cmm-gen2" },
> > + { },
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, rcar_cmm_of_table);
> > +
> > +static struct platform_driver rcar_cmm_platform_driver = {
> > + .probe = rcar_cmm_probe,
> > + .driver = {
> > + .name = "rcar-cmm",
> > + .of_match_table = rcar_cmm_of_table,
> > + },
>
> No need for suspend/resume support ? The DU driver should disable/enable
> the CMM in its suspend/resume paths, so this should be fine, but won't
> the LUT contents be lost and need to be restored ?
>
> > +};
> > +
> > +module_platform_driver(rcar_cmm_platform_driver);
> > +
> > +MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org");
>
> Missing >.
>
> > +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..da61a145dc5c
> > --- /dev/null
> > +++ b/drivers/gpu/drm/rcar-du/rcar_cmm.h
> > @@ -0,0 +1,38 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
>
> The .c and .h file licenses don't match.
>
> > +/*
> > + * 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__
> > +
> > +#include <linux/platform_device.h>
>
> You can forward-declare struct platform_device instead.
>
> > +
> > +#define CMM_GAMMA_LUT_SIZE 256
> > +
> > +struct drm_color_lut;
> > +
> > +/**
> > + * struct rcar_cmm_config - CMM configuration
> > + *
> > + * @lut: 1D-LUT configuration
> > + * @lut.enable: 1D-LUT enable flag
> > + * @lut.table: 1D-LUT table entries.
> > + * @lut.size 1D-LUT number of entries. Max is 256
>
> The last line is missing a colon.
>
> > + */
> > +struct rcar_cmm_config {
> > + struct {
> > + bool enable;
> > + struct drm_color_lut *table;
> > + unsigned int size;
> > + } lut;
> > +};
> > +
> > +int rcar_cmm_enable(struct platform_device *);
>
> As the OF API looks up a struct device from a device_node, should we use
> struct device here ?

My bad, the API actually returns a struct platform_device. I would still
prefer using struct device, but it then becomes more of a personal
preference.

> > +void rcar_cmm_disable(struct platform_device *);
>
> I find headers more readable when function arguments are named. In this
> case the types probably provide enough information, but good luck trying
> to read a function such as
>
> int foo(int, int, bool);
>
> > +
> > +int rcar_cmm_setup(struct platform_device *, struct rcar_cmm_config *);
>
> Can the second argument be const ?
>
> > +
> > +#endif /* __RCAR_CMM_H__ */

--
Regards,

Laurent Pinchart

\
 
 \ /
  Last update: 2019-06-07 13:46    [W:0.098 / U:50.732 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site