Re: [PATCH 02/10] drm: xlnx: Add xlnx crtc of Xilinx DRM KMS

From: Daniel Vetter <daniel@ffwll.ch>
To: Hyun Kwon <hyun.kwon@xilinx.com>
Cc: devicetree@vger.kernel.org,
	Michal Simek <michal.simek@xilinx.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 02/10] drm: xlnx: Add xlnx crtc of Xilinx DRM KMS
Date: Tue, 9 Jan 2018 10:37:33 +0100	[thread overview]
Message-ID: <20180109093733.GG26573@phenom.ffwll.local> (raw)
In-Reply-To: <1515117959-18068-3-git-send-email-hyun.kwon@xilinx.com>

On Thu, Jan 04, 2018 at 06:05:51PM -0800, Hyun Kwon wrote:
> xlnx_crtc is a part of Xilinx DRM KMS and a layer that
> provides some interface between the Xilinx DRM KMS and
> crtc drivers.
> 
> Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>

Personal style, but I don't see much value in these small helpers.
Splitting them from the main driver at least makes reading the patches a
bit harder. But no strong opinion, just a bikeshed, feel free to ignore
:-)
-Daniel

> ---
>  drivers/gpu/drm/xlnx/xlnx_crtc.c | 194 +++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/xlnx/xlnx_crtc.h |  70 ++++++++++++++
>  2 files changed, 264 insertions(+)
>  create mode 100644 drivers/gpu/drm/xlnx/xlnx_crtc.c
>  create mode 100644 drivers/gpu/drm/xlnx/xlnx_crtc.h
> 
> diff --git a/drivers/gpu/drm/xlnx/xlnx_crtc.c b/drivers/gpu/drm/xlnx/xlnx_crtc.c
> new file mode 100644
> index 0000000..57ee939
> --- /dev/null
> +++ b/drivers/gpu/drm/xlnx/xlnx_crtc.c
> @@ -0,0 +1,194 @@
> +/*
> + * Xilinx DRM crtc driver
> + *
> + *  Copyright (C) 2017 - 2018 Xilinx, Inc.
> + *
> + *  Author: Hyun Woo Kwon <hyun.kwon@xilinx.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0
> + */
> +
> +#include <drm/drmP.h>
> +
> +#include <linux/list.h>
> +
> +#include "xlnx_crtc.h"
> +
> +/*
> + * Overview
> + * --------
> + *
> + * The Xilinx CRTC layer is to enable the custom interface to CRTC drivers.
> + * The interface is used by Xilinx DRM driver where it needs CRTC
> + * functionailty. CRTC drivers should attach the desired callbacks
> + * to struct xlnx_crtc and register the xlnx_crtc with correcsponding
> + * drm_device. It's highly recommended CRTC drivers register all callbacks
> + * even though many of them are optional.
> + * The CRTC helper simply walks through the registered CRTC device,
> + * and call the callbacks.
> + */
> +
> +/**
> + * struct xlnx_crtc_helper - Xilinx CRTC helper
> + * @xlnx_crtcs: list of Xilinx CRTC devices
> + * @lock: lock to protect @xlnx_crtcs
> + * @drm: back pointer to DRM core
> + */
> +struct xlnx_crtc_helper {
> +	struct list_head xlnx_crtcs;
> +	struct mutex lock; /* lock for @xlnx_crtcs */
> +	struct drm_device *drm;
> +};
> +
> +#define XLNX_CRTC_MAX_HEIGHT_WIDTH	UINT_MAX
> +
> +int xlnx_crtc_helper_enable_vblank(struct xlnx_crtc_helper *helper,
> +				   unsigned int crtc_id)
> +{
> +	struct xlnx_crtc *crtc;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list)
> +		if (drm_crtc_index(&crtc->crtc) == crtc_id)
> +			if (crtc->enable_vblank)
> +				return crtc->enable_vblank(crtc);
> +	return -ENODEV;
> +}
> +
> +void xlnx_crtc_helper_disable_vblank(struct xlnx_crtc_helper *helper,
> +				     unsigned int crtc_id)
> +{
> +	struct xlnx_crtc *crtc;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list) {
> +		if (drm_crtc_index(&crtc->crtc) == crtc_id) {
> +			if (crtc->disable_vblank)
> +				crtc->disable_vblank(crtc);
> +			return;
> +		}
> +	}
> +}
> +
> +unsigned int xlnx_crtc_helper_get_align(struct xlnx_crtc_helper *helper)
> +{
> +	struct xlnx_crtc *crtc;
> +	unsigned int align = 1, tmp;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list) {
> +		if (crtc->get_align) {
> +			tmp = crtc->get_align(crtc);
> +			align = ALIGN(align, tmp);
> +		}
> +	}
> +
> +	return align;
> +}
> +
> +u64 xlnx_crtc_helper_get_dma_mask(struct xlnx_crtc_helper *helper)
> +{
> +	struct xlnx_crtc *crtc;
> +	u64 mask = DMA_BIT_MASK(sizeof(dma_addr_t) * 8), tmp;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list) {
> +		if (crtc->get_dma_mask) {
> +			tmp = crtc->get_dma_mask(crtc);
> +			mask = min(mask, tmp);
> +		}
> +	}
> +
> +	return mask;
> +}
> +
> +int xlnx_crtc_helper_get_max_width(struct xlnx_crtc_helper *helper)
> +{
> +	struct xlnx_crtc *crtc;
> +	unsigned int width = XLNX_CRTC_MAX_HEIGHT_WIDTH, tmp;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list) {
> +		if (crtc->get_max_width) {
> +			tmp = crtc->get_max_width(crtc);
> +			width = min(width, tmp);
> +		}
> +	}
> +
> +	return width;
> +}
> +
> +int xlnx_crtc_helper_get_max_height(struct xlnx_crtc_helper *helper)
> +{
> +	struct xlnx_crtc *crtc;
> +	unsigned int height = XLNX_CRTC_MAX_HEIGHT_WIDTH, tmp;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list) {
> +		if (crtc->get_max_height) {
> +			tmp = crtc->get_max_height(crtc);
> +			height = min(height, tmp);
> +		}
> +	}
> +
> +	return height;
> +}
> +
> +uint32_t xlnx_crtc_helper_get_format(struct xlnx_crtc_helper *helper)
> +{
> +	struct xlnx_crtc *crtc;
> +	u32 format = 0, tmp;
> +
> +	list_for_each_entry(crtc, &helper->xlnx_crtcs, list) {
> +		if (crtc->get_format) {
> +			tmp = crtc->get_format(crtc);
> +			if (format && format != tmp)
> +				return 0;
> +			format = tmp;
> +		}
> +	}
> +
> +	return format;
> +}
> +
> +struct xlnx_crtc_helper *xlnx_crtc_helper_init(struct drm_device *drm)
> +{
> +	struct xlnx_crtc_helper *helper;
> +
> +	helper = devm_kzalloc(drm->dev, sizeof(*helper), GFP_KERNEL);
> +	if (!helper)
> +		return ERR_PTR(-ENOMEM);
> +
> +	INIT_LIST_HEAD(&helper->xlnx_crtcs);
> +	mutex_init(&helper->lock);
> +	helper->drm = drm;
> +
> +	return helper;
> +}
> +
> +void xlnx_crtc_helper_fini(struct drm_device *drm,
> +			   struct xlnx_crtc_helper *helper)
> +{
> +	if (WARN_ON(helper->drm != drm))
> +		return;
> +
> +	if (WARN_ON(!list_empty(&helper->xlnx_crtcs)))
> +		return;
> +
> +	mutex_destroy(&helper->lock);
> +	devm_kfree(drm->dev, helper);
> +}
> +
> +void xlnx_crtc_register(struct drm_device *drm, struct xlnx_crtc *crtc)
> +{
> +	struct xlnx_crtc_helper *helper = xlnx_get_crtc_helper(drm);
> +
> +	mutex_lock(&helper->lock);
> +	list_add_tail(&crtc->list, &helper->xlnx_crtcs);
> +	mutex_unlock(&helper->lock);
> +}
> +EXPORT_SYMBOL_GPL(xlnx_crtc_register);
> +
> +void xlnx_crtc_unregister(struct drm_device *drm, struct xlnx_crtc *crtc)
> +{
> +	struct xlnx_crtc_helper *helper = xlnx_get_crtc_helper(drm);
> +
> +	mutex_lock(&helper->lock);
> +	list_del(&crtc->list);
> +	mutex_unlock(&helper->lock);
> +}
> +EXPORT_SYMBOL_GPL(xlnx_crtc_unregister);
> diff --git a/drivers/gpu/drm/xlnx/xlnx_crtc.h b/drivers/gpu/drm/xlnx/xlnx_crtc.h
> new file mode 100644
> index 0000000..db7404e
> --- /dev/null
> +++ b/drivers/gpu/drm/xlnx/xlnx_crtc.h
> @@ -0,0 +1,70 @@
> +/*
> + * Xilinx DRM crtc header
> + *
> + *  Copyright (C) 2017 - 2018 Xilinx, Inc.
> + *
> + *  Author: Hyun Woo Kwon <hyun.kwon@xilinx.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0
> + */
> +
> +#ifndef _XLNX_CRTC_H_
> +#define _XLNX_CRTC_H_
> +
> +/**
> + * struct xlnx_crtc - Xilinx CRTC device
> + * @crtc: DRM CRTC device
> + * @list: list node for Xilinx CRTC device list
> + * @enable_vblank: Enable vblank
> + * @disable_vblank: Disable vblank
> + * @get_align: Get the alignment requirement of CRTC device
> + * @get_dma_mask: Get the dma mask of CRTC device
> + * @get_max_width: Get the maximum supported width
> + * @get_max_height: Get the maximum supported height
> + * @get_format: Get the current format of CRTC device
> + */
> +struct xlnx_crtc {
> +	struct drm_crtc crtc;
> +	struct list_head list;
> +	int (*enable_vblank)(struct xlnx_crtc *crtc);
> +	void (*disable_vblank)(struct xlnx_crtc *crtc);
> +	unsigned int (*get_align)(struct xlnx_crtc *crtc);
> +	u64 (*get_dma_mask)(struct xlnx_crtc *crtc);
> +	int (*get_max_width)(struct xlnx_crtc *crtc);
> +	int (*get_max_height)(struct xlnx_crtc *crtc);
> +	uint32_t (*get_format)(struct xlnx_crtc *crtc);
> +};
> +
> +/*
> + * Helper functions: used within Xlnx DRM
> + */
> +
> +struct xlnx_crtc_helper;
> +
> +int xlnx_crtc_helper_enable_vblank(struct xlnx_crtc_helper *helper,
> +				   unsigned int crtc_id);
> +void xlnx_crtc_helper_disable_vblank(struct xlnx_crtc_helper *helper,
> +				     unsigned int crtc_id);
> +unsigned int xlnx_crtc_helper_get_align(struct xlnx_crtc_helper *helper);
> +u64 xlnx_crtc_helper_get_dma_mask(struct xlnx_crtc_helper *helper);
> +int xlnx_crtc_helper_get_max_width(struct xlnx_crtc_helper *helper);
> +int xlnx_crtc_helper_get_max_height(struct xlnx_crtc_helper *helper);
> +uint32_t xlnx_crtc_helper_get_format(struct xlnx_crtc_helper *helper);
> +
> +struct xlnx_crtc_helper *xlnx_crtc_helper_init(struct drm_device *drm);
> +void xlnx_crtc_helper_fini(struct drm_device *drm,
> +			   struct xlnx_crtc_helper *helper);
> +
> +/*
> + * CRTC registration: used by other sub-driver modules
> + */
> +
> +static inline struct xlnx_crtc *to_xlnx_crtc(struct drm_crtc *crtc)
> +{
> +	return container_of(crtc, struct xlnx_crtc, crtc);
> +}
> +
> +void xlnx_crtc_register(struct drm_device *drm, struct xlnx_crtc *crtc);
> +void xlnx_crtc_unregister(struct drm_device *drm, struct xlnx_crtc *crtc);
> +
> +#endif /* _XLNX_CRTC_H_ */
> -- 
> 2.7.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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