Re: [PATCH v4 2/6] drm/sprd: add Unisoc's drm kms master

From: Maxime Ripard <maxime@cerno.tech>
To: Kevin Tang <kevin3.tang@gmail.com>
Cc: maarten.lankhorst@linux.intel.com, sean@poorly.run,
	airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org,
	mark.rutland@arm.com, orsonzhai@gmail.com, zhang.lyra@gmail.com,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v4 2/6] drm/sprd: add Unisoc's drm kms master
Date: Wed, 24 Mar 2021 11:53:34 +0100	[thread overview]
Message-ID: <20210324105334.7pnrco53akhzjjjw@gilmour> (raw)
In-Reply-To: <20210222132822.7830-3-kevin3.tang@gmail.com>

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Hi

On Mon, Feb 22, 2021 at 09:28:18PM +0800, Kevin Tang wrote:
> Adds drm support for the Unisoc's display subsystem.
> 
> This is drm kms driver, this driver provides support for the
> application framework in Android, Yocto and more.
> 
> Application framework can access Unisoc's display internel

                                                    ^ internal

> peripherals through libdrm or libkms, it's test ok by modetest
> (DRM/KMS test tool) and Android HWComposer.
> 
> Cc: Orson Zhai <orsonzhai@gmail.com>
> Cc: Chunyan Zhang <zhang.lyra@gmail.com>
> Signed-off-by: Kevin Tang <kevin.tang@unisoc.com>
> 
> v4:
>   - Move the devm_drm_dev_alloc to master_ops->bind function.
>   - The managed drmm_mode_config_init() it is no longer necessary for drivers to explicitly call drm_mode_config_cleanup, so delete it.
> ---
>  drivers/gpu/drm/Kconfig         |   2 +
>  drivers/gpu/drm/Makefile        |   1 +
>  drivers/gpu/drm/sprd/Kconfig    |  12 ++
>  drivers/gpu/drm/sprd/Makefile   |   5 +
>  drivers/gpu/drm/sprd/sprd_drm.c | 217 ++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/sprd/sprd_drm.h |  16 +++
>  6 files changed, 253 insertions(+)
>  create mode 100644 drivers/gpu/drm/sprd/Kconfig
>  create mode 100644 drivers/gpu/drm/sprd/Makefile
>  create mode 100644 drivers/gpu/drm/sprd/sprd_drm.c
>  create mode 100644 drivers/gpu/drm/sprd/sprd_drm.h
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 8bf103de1..9d6ce2867 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -382,6 +382,8 @@ source "drivers/gpu/drm/tidss/Kconfig"
>  
>  source "drivers/gpu/drm/xlnx/Kconfig"
>  
> +source "drivers/gpu/drm/sprd/Kconfig"
> +
>  # Keep legacy drivers last
>  
>  menuconfig DRM_LEGACY
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 02c229392..42d211d9c 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -126,3 +126,4 @@ obj-$(CONFIG_DRM_ASPEED_GFX) += aspeed/
>  obj-$(CONFIG_DRM_MCDE) += mcde/
>  obj-$(CONFIG_DRM_TIDSS) += tidss/
>  obj-y			+= xlnx/
> +obj-$(CONFIG_DRM_SPRD) += sprd/
> diff --git a/drivers/gpu/drm/sprd/Kconfig b/drivers/gpu/drm/sprd/Kconfig
> new file mode 100644
> index 000000000..6e80cc9f3
> --- /dev/null
> +++ b/drivers/gpu/drm/sprd/Kconfig
> @@ -0,0 +1,12 @@
> +config DRM_SPRD
> +	tristate "DRM Support for Unisoc SoCs Platform"
> +	depends on ARCH_SPRD || COMPILE_TEST
> +	depends on DRM && OF
> +	select DRM_KMS_HELPER
> +	select DRM_GEM_CMA_HELPER
> +	select DRM_KMS_CMA_HELPER
> +	select DRM_MIPI_DSI

I guess this should rather be moved to your DSI introduction patch?

> +	help
> +	  Choose this option if you have a Unisoc chipset.
> +	  If M is selected the module will be called sprd_drm.
> +
> diff --git a/drivers/gpu/drm/sprd/Makefile b/drivers/gpu/drm/sprd/Makefile
> new file mode 100644
> index 000000000..86d95d93a
> --- /dev/null
> +++ b/drivers/gpu/drm/sprd/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +subdir-ccflags-y += -I$(srctree)/$(src)

Is it really needed? I'm not seeing any header that aren't in the
include path already.

> +obj-y := sprd_drm.o
> diff --git a/drivers/gpu/drm/sprd/sprd_drm.c b/drivers/gpu/drm/sprd/sprd_drm.c
> new file mode 100644
> index 000000000..a1d3ed655
> --- /dev/null
> +++ b/drivers/gpu/drm/sprd/sprd_drm.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Unisoc Inc.
> + */
> +
> +#include <linux/component.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/of_platform.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_gem_cma_helper.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_vblank.h>
> +
> +#include "sprd_drm.h"
> +
> +#define DRIVER_NAME	"sprd"
> +#define DRIVER_DESC	"Spreadtrum SoCs' DRM Driver"
> +#define DRIVER_DATE	"20200201"
> +#define DRIVER_MAJOR	1
> +#define DRIVER_MINOR	0
> +
> +static const struct drm_mode_config_helper_funcs sprd_drm_mode_config_helper = {
> +	.atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
> +};
> +
> +static const struct drm_mode_config_funcs sprd_drm_mode_config_funcs = {
> +	.fb_create = drm_gem_fb_create,
> +	.atomic_check = drm_atomic_helper_check,
> +	.atomic_commit = drm_atomic_helper_commit,
> +};
> +
> +static void sprd_drm_mode_config_init(struct drm_device *drm)
> +{
> +	drm->mode_config.min_width = 0;
> +	drm->mode_config.min_height = 0;
> +	drm->mode_config.max_width = 8192;
> +	drm->mode_config.max_height = 8192;
> +	drm->mode_config.allow_fb_modifiers = true;
> +
> +	drm->mode_config.funcs = &sprd_drm_mode_config_funcs;
> +	drm->mode_config.helper_private = &sprd_drm_mode_config_helper;
> +}
> +
> +DEFINE_DRM_GEM_CMA_FOPS(sprd_drm_fops);
> +
> +static struct drm_driver sprd_drm_drv = {
> +	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
> +	.fops			= &sprd_drm_fops,
> +
> +	/* GEM Operations */
> +	DRM_GEM_CMA_DRIVER_OPS,
> +
> +	.name			= DRIVER_NAME,
> +	.desc			= DRIVER_DESC,
> +	.date			= DRIVER_DATE,
> +	.major			= DRIVER_MAJOR,
> +	.minor			= DRIVER_MINOR,
> +};
> +
> +static int sprd_drm_bind(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct drm_device *drm;
> +	struct sprd_drm *sprd;
> +	int ret;
> +
> +	sprd = devm_drm_dev_alloc(dev, &sprd_drm_drv, struct sprd_drm, drm);
> +	if (IS_ERR(sprd))
> +		return PTR_ERR(sprd);
> +
> +	drm = &sprd->drm;
> +	platform_set_drvdata(pdev, drm);
> +
> +	ret = drmm_mode_config_init(drm);
> +	if (ret)
> +		return ret;
> +
> +	sprd_drm_mode_config_init(drm);
> +
> +	/* bind and init sub drivers */
> +	ret = component_bind_all(drm->dev, drm);
> +	if (ret) {
> +		drm_err(drm, "failed to bind all component.\n");
> +		return ret;
> +	}
> +
> +	/* vblank init */
> +	ret = drm_vblank_init(drm, drm->mode_config.num_crtc);
> +	if (ret) {
> +		drm_err(drm, "failed to initialize vblank.\n");
> +		goto err_unbind_all;
> +	}
> +	/* with irq_enabled = true, we can use the vblank feature. */
> +	drm->irq_enabled = true;
> +
> +	/* reset all the states of crtc/plane/encoder/connector */
> +	drm_mode_config_reset(drm);
> +
> +	/* init kms poll for handling hpd */
> +	drm_kms_helper_poll_init(drm);
> +
> +	ret = drm_dev_register(drm, 0);
> +	if (ret < 0)
> +		goto err_kms_helper_poll_fini;
> +
> +	return 0;
> +
> +err_kms_helper_poll_fini:
> +	drm_kms_helper_poll_fini(drm);
> +err_unbind_all:
> +	component_unbind_all(drm->dev, drm);
> +	return ret;
> +}
> +
> +static void sprd_drm_unbind(struct device *dev)
> +{
> +	struct drm_device *drm = dev_get_drvdata(dev);
> +
> +	drm_dev_unregister(drm);
> +
> +	drm_kms_helper_poll_fini(drm);
> +
> +	component_unbind_all(drm->dev, drm);
> +}
> +
> +static const struct component_master_ops drm_component_ops = {
> +	.bind = sprd_drm_bind,
> +	.unbind = sprd_drm_unbind,
> +};
> +
> +static int compare_of(struct device *dev, void *data)
> +{
> +	return dev->of_node == data;
> +}
> +
> +static int sprd_drm_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	ret = dma_set_mask_and_coherent(dev, ~0UL);
> +	if (ret) {
> +		dev_err(dev, "dma_set_mask_and_coherent failed (%d)\n", ret);
> +		return ret;
> +	}

It's not really clear to me what it's here for. Could you explain with a
comment here?

Thanks
Maxime

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