2024-03-13 18:51:25

by Louis Chauvet

[permalink] [raw]
Subject: [PATCH v5 03/16] drm/vkms: write/update the documentation for pixel conversion and pixel write functions

Add some documentation on pixel conversion functions.
Update of outdated comments for pixel_write functions.

Signed-off-by: Louis Chauvet <[email protected]>
---
drivers/gpu/drm/vkms/vkms_composer.c | 7 ++++
drivers/gpu/drm/vkms/vkms_drv.h | 13 ++++++++
drivers/gpu/drm/vkms/vkms_formats.c | 62 ++++++++++++++++++++++++++++++------
3 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index c6d9b4a65809..da0651a94c9b 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -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);

diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index b4b357447292..18086423a3a7 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -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
+ * @dst: destination rectangle in the crtc buffer
+ * @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;
@@ -52,6 +63,8 @@ struct vkms_writeback_job {
* 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 vkms_plane_state must
+ * ensure that this pointer is valid
*/
struct vkms_plane_state {
struct drm_shadow_plane_state base;
diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
index 172830a3936a..6e3dc8682ff9 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -9,6 +9,18 @@

#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)
{
struct drm_framebuffer *fb = frame_info->fb;
@@ -17,18 +29,22 @@ static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int
+ (x * fb->format->cpp[0]);
}

-/*
- * 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)
@@ -53,6 +69,13 @@ 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)
{
/*
@@ -145,12 +168,11 @@ 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 argb_u16 pixel 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 the `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)
{
@@ -216,6 +238,14 @@ static void argb_u16_to_RGB565(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
*pixels = cpu_to_le16(r << 11 | g << 5 | b);
}

+/**
+ * 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)
{
@@ -229,6 +259,13 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
wb->pixel_write(dst_pixels, &in_pixels[x]);
}

+/**
+ * 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) {
@@ -247,6 +284,13 @@ void *get_pixel_conversion_function(u32 format)
}
}

+/**
+ * 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) {

--
2.43.0



2024-03-13 19:23:33

by Randy Dunlap

[permalink] [raw]
Subject: Re: [PATCH v5 03/16] drm/vkms: write/update the documentation for pixel conversion and pixel write functions

Hi,

On 3/13/24 10:44, Louis Chauvet wrote:
> Add some documentation on pixel conversion functions.
> Update of outdated comments for pixel_write functions.
>
> Signed-off-by: Louis Chauvet <[email protected]>
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 7 ++++
> drivers/gpu/drm/vkms/vkms_drv.h | 13 ++++++++
> drivers/gpu/drm/vkms/vkms_formats.c | 62 ++++++++++++++++++++++++++++++------
> 3 files changed, 73 insertions(+), 9 deletions(-)
>

> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 172830a3936a..6e3dc8682ff9 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c


> @@ -216,6 +238,14 @@ static void argb_u16_to_RGB565(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
> *pixels = cpu_to_le16(r << 11 | g << 5 | b);
> }
>
> +/**

This comment is not in kernel-doc format, so either use "/*" to begin the comment
or add the function name in the first comment line, like:


+ * vkms_writeback_row - Generic loop for all supported writeback format. It is executed just after the blending to

> + * 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)
> {
> @@ -229,6 +259,13 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
> wb->pixel_write(dst_pixels, &in_pixels[x]);
> }
>
> +/**

Needs function name or don't use "/**" to begin the comment.

> + * 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) {
> @@ -247,6 +284,13 @@ void *get_pixel_conversion_function(u32 format)
> }
> }
>
> +/**

Same here.

> + * 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) {
>

thanks.
--
#Randy

2024-03-25 23:29:12

by Maíra Canal

[permalink] [raw]
Subject: Re: [PATCH v5 03/16] drm/vkms: write/update the documentation for pixel conversion and pixel write functions

On 3/13/24 14:44, Louis Chauvet wrote:
> Add some documentation on pixel conversion functions.
> Update of outdated comments for pixel_write functions.
>
> Signed-off-by: Louis Chauvet <[email protected]>
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 7 ++++
> drivers/gpu/drm/vkms/vkms_drv.h | 13 ++++++++
> drivers/gpu/drm/vkms/vkms_formats.c | 62 ++++++++++++++++++++++++++++++------
> 3 files changed, 73 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index c6d9b4a65809..da0651a94c9b 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -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);
>
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index b4b357447292..18086423a3a7 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -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
> + * @dst: destination rectangle in the crtc buffer
> + * @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;
> @@ -52,6 +63,8 @@ struct vkms_writeback_job {
> * vkms_plane_state - Driver specific plane state

It should be "* 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 vkms_plane_state must
> + * ensure that this pointer is valid
> */
> struct vkms_plane_state {
> struct drm_shadow_plane_state base;
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 172830a3936a..6e3dc8682ff9 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -9,6 +9,18 @@
>
> #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)
> {
> struct drm_framebuffer *fb = frame_info->fb;
> @@ -17,18 +29,22 @@ static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int
> + (x * fb->format->cpp[0]);
> }
>
> -/*
> - * 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

I would add a space after x and y.

> *
> * 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)
> @@ -53,6 +69,13 @@ 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

Double-spacing.

> + * ARGB16161616 in out_pixel.
> + *
> + * They are used in the `vkms_compose_row` function to handle multiple formats.

For cross-referencing functions, we use vkms_compose_row() [1].

[1]
https://docs.kernel.org/doc-guide/kernel-doc.html#highlights-and-cross-references

> + */
> +
> static void ARGB8888_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
> {
> /*
> @@ -145,12 +168,11 @@ 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 argb_u16 pixel and convert it to a specific format. The

For cross-referencing structs, look here [1].

> + * 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 the `vkms_writeback_row` to convert and store a pixel from the src_buffer to

Same.

> + * the writeback buffer.
> */
> static void argb_u16_to_ARGB8888(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
> {
> @@ -216,6 +238,14 @@ static void argb_u16_to_RGB565(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
> *pixels = cpu_to_le16(r << 11 | g << 5 | b);
> }
>
> +/**
> + * 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)
> {
> @@ -229,6 +259,13 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
> wb->pixel_write(dst_pixels, &in_pixels[x]);
> }
>
> +/**

Where is the function name?

> + * 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) {
> @@ -247,6 +284,13 @@ void *get_pixel_conversion_function(u32 format)
> }
> }
>
> +/**

Same.

Best Regards,
- Maíra

> + * 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) {
>

2024-03-26 15:58:28

by Louis Chauvet

[permalink] [raw]
Subject: Re: [PATCH v5 03/16] drm/vkms: write/update the documentation for pixel conversion and pixel write functions

Le 25/03/24 - 10:32, Ma?ra Canal a ?crit :
> On 3/13/24 14:44, Louis Chauvet wrote:
> > Add some documentation on pixel conversion functions.
> > Update of outdated comments for pixel_write functions.
> >
> > Signed-off-by: Louis Chauvet <[email protected]>
> > ---
> > drivers/gpu/drm/vkms/vkms_composer.c | 7 ++++
> > drivers/gpu/drm/vkms/vkms_drv.h | 13 ++++++++
> > drivers/gpu/drm/vkms/vkms_formats.c | 62 ++++++++++++++++++++++++++++++------
> > 3 files changed, 73 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> > index c6d9b4a65809..da0651a94c9b 100644
> > --- a/drivers/gpu/drm/vkms/vkms_composer.c
> > +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> > @@ -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);
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> > index b4b357447292..18086423a3a7 100644
> > --- a/drivers/gpu/drm/vkms/vkms_drv.h
> > +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> > @@ -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
> > + * @dst: destination rectangle in the crtc buffer
> > + * @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;
> > @@ -52,6 +63,8 @@ struct vkms_writeback_job {
> > * vkms_plane_state - Driver specific plane state
>
> It should be "* struct vkms_plane_state - Driver specific plane state".

Fixed in v6.

> > * @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 vkms_plane_state must
> > + * ensure that this pointer is valid
> > */
> > struct vkms_plane_state {
> > struct drm_shadow_plane_state base;
> > diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> > index 172830a3936a..6e3dc8682ff9 100644
> > --- a/drivers/gpu/drm/vkms/vkms_formats.c
> > +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> > @@ -9,6 +9,18 @@
> >
> > #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)
> > {
> > struct drm_framebuffer *fb = frame_info->fb;
> > @@ -17,18 +29,22 @@ static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int
> > + (x * fb->format->cpp[0]);
> > }
> >
> > -/*
> > - * 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
>
> I would add a space after x and y.

I just followed what was here before, fixed for the v6.

> > *
> > * 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)
> > @@ -53,6 +69,13 @@ 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
>
> Double-spacing.

Fixed in v6.

> > + * ARGB16161616 in out_pixel.
> > + *
> > + * They are used in the `vkms_compose_row` function to handle multiple formats.
>
> For cross-referencing functions, we use vkms_compose_row() [1].
>
> [1]
> https://docs.kernel.org/doc-guide/kernel-doc.html#highlights-and-cross-references

Thanks for this reference, fixed for the v6

> > + */
> > +
> > static void ARGB8888_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
> > {
> > /*
> > @@ -145,12 +168,11 @@ 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 argb_u16 pixel and convert it to a specific format. The
>
> For cross-referencing structs, look here [1].

Fixed in v6.

> > + * 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 the `vkms_writeback_row` to convert and store a pixel from the src_buffer to
>
> Same.

Fixed in v6.

> > + * the writeback buffer.
> > */
> > static void argb_u16_to_ARGB8888(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
> > {
> > @@ -216,6 +238,14 @@ static void argb_u16_to_RGB565(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
> > *pixels = cpu_to_le16(r << 11 | g << 5 | b);
> > }
> >
> > +/**
> > + * 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)
> > {
> > @@ -229,6 +259,13 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
> > wb->pixel_write(dst_pixels, &in_pixels[x]);
> > }
> >
> > +/**
>
> Where is the function name?

Fixed for the v6.

> > + * 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) {
> > @@ -247,6 +284,13 @@ void *get_pixel_conversion_function(u32 format)
> > }
> > }
> >
> > +/**
>
> Same.

Fixed for the v6.

Thanks,
Louis Chauvet

> Best Regards,
> - Ma?ra
>
> > + * 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) {
> >

--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com