drm/vkms: Add documentation (6e5eb6dc) · Commits · git / linux-net

drivers/gpu/drm/vkms/vkms_composer.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -189,6 +189,13 @@ static void blend(struct vkms_writeback_job *wb,

		size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;

		/*
		* The planes are composed line-by-line to avoid heavy memory usage. It is a necessary
		* complexity to avoid poor blending performance.
		*
		* The function vkms_compose_row() is used to read a line, pixel-by-pixel, into the staging
		* buffer.
		*/
		for (size_t y = 0; y < crtc_y_limit; y++) {
		fill_background(&background_color, output_buffer);

drivers/gpu/drm/vkms/vkms_drv.h

+88 −13

Original line number	Diff line number	Diff line
		@@ -25,6 +25,17 @@

		#define VKMS_LUT_SIZE 256

		/**
		* struct vkms_frame_info - Structure to store the state of a frame
		*
		* @fb: backing drm framebuffer
		* @src: source rectangle of this frame in the source framebuffer, stored in 16.16 fixed-point form
		* @dst: destination rectangle in the crtc buffer, stored in whole pixel units
		* @map: see @drm_shadow_plane_state.data
		* @rotation: rotation applied to the source.
		*
		* @src and @dst should have the same size modulo the rotation.
		*/
		struct vkms_frame_info {
		struct drm_framebuffer *fb;
		struct drm_rect src, dst;
		@@ -52,9 +63,11 @@ struct vkms_writeback_job {
		};

		/**
		* vkms_plane_state - Driver specific plane state
		* struct vkms_plane_state - Driver specific plane state
		* @base: base plane state
		* @frame_info: data required for composing computation
		* @pixel_read: function to read a pixel in this plane. The creator of a struct vkms_plane_state
		* must ensure that this pointer is valid
		*/
		struct vkms_plane_state {
		struct drm_shadow_plane_state base;
		@@ -73,29 +86,56 @@ struct vkms_color_lut {
		};

		/**
		* vkms_crtc_state - Driver specific CRTC state
		* struct vkms_crtc_state - Driver specific CRTC state
		*
		* @base: base CRTC state
		* @composer_work: work struct to compose and add CRC entries
		* @n_frame_start: start frame number for computed CRC
		* @n_frame_end: end frame number for computed CRC
		*
		* @num_active_planes: Number of active planes
		* @active_planes: List containing all the active planes (counted by
		* @num_active_planes). They should be stored in z-order.
		* @active_writeback: Current active writeback job
		* @gamma_lut: Look up table for gamma used in this CRTC
		* @crc_pending: Protected by @vkms_output.composer_lock, true when the frame CRC is not computed
		* yet. Used by vblank to detect if the composer is too slow.
		* @wb_pending: Protected by @vkms_output.composer_lock, true when a writeback frame is requested.
		* @frame_start: Protected by @vkms_output.composer_lock, saves the frame number before the start
		* of the composition process.
		* @frame_end: Protected by @vkms_output.composer_lock, saves the last requested frame number.
		* This is used to generate enough CRC entries when the composition worker is too slow.
		*/
		struct vkms_crtc_state {
		struct drm_crtc_state base;
		struct work_struct composer_work;

		int num_active_planes;
		/* stack of active planes for crc computation, should be in z order */
		struct vkms_plane_state **active_planes;
		struct vkms_writeback_job *active_writeback;
		struct vkms_color_lut gamma_lut;

		/* below four are protected by vkms_output.composer_lock */
		bool crc_pending;
		bool wb_pending;
		u64 frame_start;
		u64 frame_end;
		};

		/**
		* struct vkms_output - Internal representation of all output components in VKMS
		*
		* @crtc: Base CRTC in DRM
		* @encoder: DRM encoder used for this output
		* @connector: DRM connector used for this output
		* @wb_connecter: DRM writeback connector used for this output
		* @vblank_hrtimer: Timer used to trigger the vblank
		* @period_ns: vblank period, in nanoseconds, used to configure @vblank_hrtimer and to compute
		* vblank timestamps
		* @composer_workq: Ordered workqueue for @composer_state.composer_work.
		* @lock: Lock used to protect concurrent access to the composer
		* @composer_enabled: Protected by @lock, true when the VKMS composer is active (crc needed or
		* writeback)
		* @composer_state: Protected by @lock, current state of this VKMS output
		* @composer_lock: Lock used internally to protect @composer_state members
		*/
		struct vkms_output {
		struct drm_crtc crtc;
		struct drm_encoder encoder;
		@@ -103,28 +143,38 @@ struct vkms_output {
		struct drm_writeback_connector wb_connector;
		struct hrtimer vblank_hrtimer;
		ktime_t period_ns;
		/* ordered wq for composer_work */
		struct workqueue_struct *composer_workq;
		/* protects concurrent access to composer */
		spinlock_t lock;

		/* protected by @lock */
		bool composer_enabled;
		struct vkms_crtc_state *composer_state;

		spinlock_t composer_lock;
		};

		struct vkms_device;

		/**
		* struct vkms_config - General configuration for VKMS driver
		*
		* @writeback: If true, a writeback buffer can be attached to the CRTC
		* @cursor: If true, a cursor plane is created in the VKMS device
		* @overlay: If true, NUM_OVERLAY_PLANES will be created for the VKMS device
		* @dev: Used to store the current VKMS device. Only set when the device is instantiated.
		*/
		struct vkms_config {
		bool writeback;
		bool cursor;
		bool overlay;
		/* only set when instantiated */
		struct vkms_device *dev;
		};

		/**
		* struct vkms_device - Description of a VKMS device
		*
		* @drm - Base device in DRM
		* @platform - Associated platform device
		* @output - Configuration and sub-components of the VKMS device
		* @config: Configuration used in this VKMS device
		*/
		struct vkms_device {
		struct drm_device drm;
		struct platform_device *platform;
		@@ -132,6 +182,10 @@ struct vkms_device {
		const struct vkms_config *config;
		};

		/*
		* The following helpers are used to convert a member of a struct into its parent.
		*/

		#define drm_crtc_to_vkms_output(target) \
		container_of(target, struct vkms_output, crtc)

		@@ -144,12 +198,33 @@ struct vkms_device {
		#define to_vkms_plane_state(target)\
		container_of(target, struct vkms_plane_state, base.base)

		/* CRTC */
		/**
		* vkms_crtc_init() - Initialize a CRTC for VKMS
		* @dev: DRM device associated with the VKMS buffer
		* @crtc: uninitialized CRTC device
		* @primary: primary plane to attach to the CRTC
		* @cursor: plane to attach to the CRTC
		*/
		int vkms_crtc_init(struct drm_device dev, struct drm_crtc crtc,
		struct drm_plane primary, struct drm_plane cursor);

		/**
		* vkms_output_init() - Initialize all sub-components needed for a VKMS device.
		*
		* @vkmsdev: VKMS device to initialize
		* @index: CRTC which can be attached to the planes. The caller must ensure that
		* @index is positive and less or equals to 31.
		*/
		int vkms_output_init(struct vkms_device *vkmsdev, int index);

		/**
		* vkms_plane_init() - Initialize a plane
		*
		* @vkmsdev: VKMS device containing the plane
		* @type: type of plane to initialize
		* @index: CRTC which can be attached to the plane. The caller must ensure that
		* @index is positive and less or equals to 31.
		*/
		struct vkms_plane vkms_plane_init(struct vkms_device vkmsdev,
		enum drm_plane_type type, int index);

drivers/gpu/drm/vkms/vkms_formats.c

+53 −9

Original line number	Diff line number	Diff line
		@@ -9,24 +9,40 @@

		#include "vkms_formats.h"

		/**
		* pixel_offset() - Get the offset of the pixel at coordinates x/y in the first plane
		*
		* @frame_info: Buffer metadata
		* @x: The x coordinate of the wanted pixel in the buffer
		* @y: The y coordinate of the wanted pixel in the buffer
		*
		* The caller must ensure that the framebuffer associated with this request uses a pixel format
		* where block_h == block_w == 1.
		* If this requirement is not fulfilled, the resulting offset can point to an other pixel or
		* outside of the buffer.
		*/
		static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int y)
		{
		return frame_info->offset + (y * frame_info->pitch)
		+ (x * frame_info->cpp);
		}

		/*
		* packed_pixels_addr - Get the pointer to pixel of a given pair of coordinates
		/**
		* packed_pixels_addr() - Get the pointer to the block containing the pixel at the given
		* coordinates
		*
		* @frame_info: Buffer metadata
		* @x: The x(width) coordinate of the 2D buffer
		* @y: The y(Heigth) coordinate of the 2D buffer
		* @x: The x (width) coordinate inside the plane
		* @y: The y (height) coordinate inside the plane
		*
		* Takes the information stored in the frame_info, a pair of coordinates, and
		* returns the address of the first color channel.
		* This function assumes the channels are packed together, i.e. a color channel
		* comes immediately after another in the memory. And therefore, this function
		* doesn't work for YUV with chroma subsampling (e.g. YUV420 and NV21).
		*
		* The caller must ensure that the framebuffer associated with this request uses a pixel format
		* where block_h == block_w == 1, otherwise the returned pointer can be outside the buffer.
		*/
		static void packed_pixels_addr(const struct vkms_frame_info frame_info,
		int x, int y)
		@@ -51,6 +67,13 @@ static int get_x_position(const struct vkms_frame_info *frame_info, int limit, i
		return x;
		}

		/*
		* The following functions take pixel data from the buffer and convert them to the format
		* ARGB16161616 in @out_pixel.
		*
		* They are used in the vkms_compose_row() function to handle multiple formats.
		*/

		static void ARGB8888_to_argb_u16(u8 src_pixels, struct pixel_argb_u16 out_pixel)
		{
		/*
		@@ -143,12 +166,11 @@ void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state
		}

		/*
		* The following functions take an line of argb_u16 pixels from the
		* src_buffer, convert them to a specific format, and store them in the
		* destination.
		* The following functions take one &struct pixel_argb_u16 and convert it to a specific format.
		* The result is stored in @dst_pixels.
		*
		* They are used in the `compose_active_planes` to convert and store a line
		* from the src_buffer to the writeback buffer.
		* They are used in vkms_writeback_row() to convert and store a pixel from the src_buffer to
		* the writeback buffer.
		*/
		static void argb_u16_to_ARGB8888(u8 dst_pixels, struct pixel_argb_u16 in_pixel)
		{
		@@ -214,6 +236,14 @@ static void argb_u16_to_RGB565(u8 dst_pixels, struct pixel_argb_u16 in_pixel)
		*pixels = cpu_to_le16(r << 11 \| g << 5 \| b);
		}

		/**
		* vkms_writeback_row() - Generic loop for all supported writeback format. It is executed just
		* after the blending to write a line in the writeback buffer.
		*
		* @wb: Job where to insert the final image
		* @src_buffer: Line to write
		* @y: Row to write in the writeback buffer
		*/
		void vkms_writeback_row(struct vkms_writeback_job *wb,
		const struct line_buffer *src_buffer, int y)
		{
		@@ -227,6 +257,13 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
		wb->pixel_write(dst_pixels, &in_pixels[x]);
		}

		/**
		* get_pixel_conversion_function() - Retrieve the correct read_pixel function for a specific
		* format. The returned pointer is NULL for unsupported pixel formats. The caller must ensure that
		* the pointer is valid before using it in a vkms_plane_state.
		*
		* @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
		*/
		void *get_pixel_conversion_function(u32 format)
		{
		switch (format) {
		@@ -245,6 +282,13 @@ void *get_pixel_conversion_function(u32 format)
		}
		}

		/**
		* get_pixel_write_function() - Retrieve the correct write_pixel function for a specific format.
		* The returned pointer is NULL for unsupported pixel formats. The caller must ensure that the
		* pointer is valid before using it in a vkms_writeback_job.
		*
		* @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
		*/
		void *get_pixel_write_function(u32 format)
		{
		switch (format) {

drivers/gpu/drm/vkms/vkms_output.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@ static int vkms_conn_get_modes(struct drm_connector *connector)
		{
		int count;

		/* Use the default modes list from DRM */
		count = drm_add_modes_noedid(connector, XRES_MAX, YRES_MAX);
		drm_set_preferred_mode(connector, XRES_DEF, YRES_DEF);

		@@ -58,6 +59,12 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
		int writeback;
		unsigned int n;

		/*
		* Initialize used plane. One primary plane is required to perform the composition.
		*
		* The overlay and cursor planes are not mandatory, but can be used to perform complex
		* composition.
		*/
		primary = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_PRIMARY, index);
		if (IS_ERR(primary))
		return PTR_ERR(primary);
		@@ -76,6 +83,7 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
		return PTR_ERR(cursor);
		}

		/* [1]: Allocation of a CRTC, its index will be BIT(0) = 1 */
		ret = vkms_crtc_init(dev, crtc, &primary->base, &cursor->base);
		if (ret)
		return ret;
		@@ -95,7 +103,11 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
		DRM_ERROR("Failed to init encoder\n");
		goto err_encoder;
		}
		encoder->possible_crtcs = 1;
		/*
		* This is a hardcoded value to select crtc for the encoder.
		* BIT(0) here designate the first registered CRTC, the one allocated in [1]
		*/
		encoder->possible_crtcs = BIT(0);

		ret = drm_connector_attach_encoder(connector, encoder);
		if (ret) {