Re: [PATCH v8 5/5] drm: xlnx: ZynqMP DP subsystem DRM KMS driver

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Hyun,

Thank you for the patch.

On Sat, Jul 07, 2018 at 07:05:38PM -0700, Hyun Kwon wrote:
> This is a wrapper around the ZynqMP Display and DisplayPort drivers.

This isn't quite accurate. There's a single driver, named zynqmp-dpsub, split
in a few source files. You've split the code in several patches to ease review
(thank you for that !), but this patch isn't a wrapper, it's the top-level
entry point for the driver.

> Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
> v8
> - Support reserved memory through memory-region dt binding
> v6
> - Accomodate the migration of logical master from platform device to device
> - Remove the duplicate license paragraphs
> - Do complete forward declaration in the header
> v5
> - Add an error handling of pipeline initialization
> v4
> - Use the newly added xlnx pipeline calls to initialize drm device
> v2
> - Change the SPDX identifier format
> ---
> ---
>  drivers/gpu/drm/xlnx/Kconfig        |  11 +++
>  drivers/gpu/drm/xlnx/Makefile       |   3 +
>  drivers/gpu/drm/xlnx/zynqmp_dpsub.c | 158 ++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xlnx/zynqmp_dpsub.h |  23 ++++++
>  4 files changed, 195 insertions(+)
>  create mode 100644 drivers/gpu/drm/xlnx/zynqmp_dpsub.c
>  create mode 100644 drivers/gpu/drm/xlnx/zynqmp_dpsub.h
> 
> diff --git a/drivers/gpu/drm/xlnx/Kconfig b/drivers/gpu/drm/xlnx/Kconfig
> index 19fd7cd..7c5529c 100644
> --- a/drivers/gpu/drm/xlnx/Kconfig
> +++ b/drivers/gpu/drm/xlnx/Kconfig
> @@ -10,3 +10,14 @@ config DRM_XLNX
>  	  display pipeline using Xilinx IPs in FPGA. This module
>  	  provides the kernel mode setting functionalities
>  	  for Xilinx display drivers.
> +
> +config DRM_ZYNQMP_DPSUB
> +	tristate "ZynqMP DP Subsystem Driver"

Should we spell DisplayPort in full here to make it easier to understand, or is
"ZynqMP DP" used through the Xiinx documentation in a way that makes the
configuration option title impossible to mistake for users ?

> +	depends on ARCH_ZYNQMP && OF && DRM_XLNX && COMMON_CLK
> +	select DMA_ENGINE
> +	select GENERIC_PHY
> +	help
> +	  DRM KMS driver for ZynqMP DP Subsystem controller. Choose
> +	  this option if you have a Xilinx ZynqMP SoC with DisplayPort
> +	  subsystem. The driver provides the kernel mode setting
> +	  functionlaities for ZynqMP DP subsystem.

s/functionlaities/functionality/

Or maybe just "The driver provides kernel mode setting for the ZynqMP DP
subsystem". Or drop that sentence as it says pretty much the same thing as the
first one :-)

> diff --git a/drivers/gpu/drm/xlnx/Makefile b/drivers/gpu/drm/xlnx/Makefile
> index c60a281..064a05a 100644
> --- a/drivers/gpu/drm/xlnx/Makefile
> +++ b/drivers/gpu/drm/xlnx/Makefile
> @@ -1,2 +1,5 @@
>  xlnx_drm-objs += xlnx_crtc.o xlnx_drv.o xlnx_fb.o xlnx_gem.o
>  obj-$(CONFIG_DRM_XLNX) += xlnx_drm.o
> +
> +zynqmp-dpsub-objs += zynqmp_disp.o zynqmp_dpsub.o zynqmp_dp.o
> +obj-$(CONFIG_DRM_ZYNQMP_DPSUB) += zynqmp-dpsub.o
> diff --git a/drivers/gpu/drm/xlnx/zynqmp_dpsub.c b/drivers/gpu/drm/xlnx/zynqmp_dpsub.c
> new file mode 100644
> index 0000000..34e81d0
> --- /dev/null
> +++ b/drivers/gpu/drm/xlnx/zynqmp_dpsub.c
> @@ -0,0 +1,158 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ZynqMP DP Subsystem Driver
> + *
> + *  Copyright (C) 2017 - 2018 Xilinx, Inc.
> + *
> + *  Author: Hyun Woo Kwon <hyun.kwon@xilinx.com>
> + */
> +
> +#include <linux/component.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "xlnx_drv.h"
> +
> +#include "zynqmp_disp.h"
> +#include "zynqmp_dp.h"
> +#include "zynqmp_dpsub.h"
> +
> +static int
> +zynqmp_dpsub_bind(struct device *dev, struct device *master, void *data)
> +{
> +	int ret;
> +
> +	ret = zynqmp_disp_bind(dev, master, data);

This isn't a component helper. You can pass it pointers to zynqmp_dpsub and
drm_device instead of retrieving them internally through platform device data.
The pointer to master is not needed. Same for zynqmp_dp_bind() below and the
corresponding unbind functions.

> +	if (ret)
> +		return ret;
> +
> +	/* zynqmp_disp should bind first, so zynqmp_dp encoder can find crtc */
> +	ret = zynqmp_dp_bind(dev, master, data);
> +	if (ret)

Shouldn't you call zynqmp_disp_unbind() here ?

> +		return ret;
> +
> +	return 0;
> +}
> +
> +static void
> +zynqmp_dpsub_unbind(struct device *dev, struct device *master, void *data)
> +{
> +	zynqmp_dp_unbind(dev, master, data);
> +	zynqmp_disp_unbind(dev, master, data);
> +}
> +
> +static const struct component_ops zynqmp_dpsub_component_ops = {
> +	.bind	= zynqmp_dpsub_bind,
> +	.unbind	= zynqmp_dpsub_unbind,
> +};
> +
> +static int zynqmp_dpsub_probe(struct platform_device *pdev)
> +{
> +	struct zynqmp_dpsub *dpsub;
> +	int ret;
> +
> +	dpsub = devm_kzalloc(&pdev->dev, sizeof(*dpsub), GFP_KERNEL);
> +	if (!dpsub)
> +		return -ENOMEM;
> +
> +	/* Sub-driver will access dpsub from drvdata */
> +	platform_set_drvdata(pdev, dpsub);
> +	pm_runtime_enable(&pdev->dev);
> +
> +	/*
> +	 * DP should be probed first so that the zynqmp_disp can set the output
> +	 * format accordingly.
> +	 */
> +	ret = zynqmp_dp_probe(pdev);
> +	if (ret)
> +		goto err_pm;
> +
> +	ret = zynqmp_disp_probe(pdev);
> +	if (ret)
> +		goto err_dp;
> +
> +	ret = component_add(&pdev->dev, &zynqmp_dpsub_component_ops);
> +	if (ret)
> +		goto err_disp;
> +
> +	/* Try the reserved memory. Proceed if there's none */
> +	of_reserved_mem_device_init(&pdev->dev);
> +
> +	/* Populate the sound child nodes */
> +	ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to populate child nodes\n");
> +		goto err_rmem;
> +	}
> +
> +	dpsub->master = xlnx_drm_pipeline_init(&pdev->dev);
> +	if (IS_ERR(dpsub->master)) {
> +		dev_err(&pdev->dev, "failed to initialize the drm pipeline\n");
> +		goto err_populate;
> +	}
> +
> +	dev_info(&pdev->dev, "ZynqMP DisplayPort Subsystem driver probed");
> +
> +	return 0;
> +
> +err_populate:
> +	of_platform_depopulate(&pdev->dev);
> +err_rmem:
> +	of_reserved_mem_device_release(&pdev->dev);
> +	component_del(&pdev->dev, &zynqmp_dpsub_component_ops);
> +err_disp:
> +	zynqmp_disp_remove(pdev);
> +err_dp:
> +	zynqmp_dp_remove(pdev);
> +err_pm:
> +	pm_runtime_disable(&pdev->dev);
> +	return ret;
> +}
> +
> +static int zynqmp_dpsub_remove(struct platform_device *pdev)
> +{
> +	struct zynqmp_dpsub *dpsub = platform_get_drvdata(pdev);
> +	int err, ret = 0;
> +
> +	xlnx_drm_pipeline_exit(dpsub->master);
> +	of_platform_depopulate(&pdev->dev);
> +	of_reserved_mem_device_release(&pdev->dev);
> +	component_del(&pdev->dev, &zynqmp_dpsub_component_ops);
> +
> +	err = zynqmp_disp_remove(pdev);
> +	if (err)
> +		ret = -EIO;
> +
> +	err = zynqmp_dp_remove(pdev);
> +	if (err)
> +		ret = -EIO;

These two functions always return 0, let's make them void, and drop error
handling here.

> +
> +	pm_runtime_disable(&pdev->dev);
> +
> +	return err;
> +}
> +
> +static const struct of_device_id zynqmp_dpsub_of_match[] = {
> +	{ .compatible = "xlnx,zynqmp-dpsub-1.7", },
> +	{ /* end of table */ },
> +};
> +MODULE_DEVICE_TABLE(of, zynqmp_dpsub_of_match);
> +
> +static struct platform_driver zynqmp_dpsub_driver = {
> +	.probe			= zynqmp_dpsub_probe,
> +	.remove			= zynqmp_dpsub_remove,
> +	.driver			= {
> +		.owner		= THIS_MODULE,
> +		.name		= "zynqmp-display",
> +		.of_match_table	= zynqmp_dpsub_of_match,
> +	},
> +};
> +
> +module_platform_driver(zynqmp_dpsub_driver);
> +
> +MODULE_AUTHOR("Xilinx, Inc.");
> +MODULE_DESCRIPTION("ZynqMP DP Subsystem Driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/gpu/drm/xlnx/zynqmp_dpsub.h b/drivers/gpu/drm/xlnx/zynqmp_dpsub.h
> new file mode 100644
> index 0000000..95239bb
> --- /dev/null
> +++ b/drivers/gpu/drm/xlnx/zynqmp_dpsub.h
> @@ -0,0 +1,23 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ZynqMP DPSUB Subsystem Driver
> + *
> + *  Copyright (C) 2017 - 2018 Xilinx, Inc.
> + *
> + *  Author: Hyun Woo Kwon <hyun.kwon@xilinx.com>
> + */
> +
> +#ifndef _ZYNQMP_DPSUB_H_
> +#define _ZYNQMP_DPSUB_H_
> +
> +struct device;
> +struct zynqmp_dp;
> +struct zynqmp_disp;

zynqmp_disp first in alphabetical order.

> +
> +struct zynqmp_dpsub {
> +	struct zynqmp_dp *dp;
> +	struct zynqmp_disp *disp;
> +	struct device *master;
> +};
> +
> +#endif /* _ZYNQMP_DPSUB_H_ */

-- 
Regards,

Laurent Pinchart
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