linux-kernel - Re: [PATCH v6 2/4] drm/rect: Add drm_rect

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Message-ID: <87sev926na.fsf@intel.com>
Date: Mon, 12 Aug 2024 16:49:13 +0300
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Jocelyn Falempe <jfalempe@...hat.com>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Daniel Vetter <daniel@...ll.ch>, Miguel Ojeda <ojeda@...nel.org>, Alex
 Gaynor <alex.gaynor@...il.com>, Wedson Almeida Filho <wedsonaf@...il.com>,
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, Bjorn Roy
 Baron <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>,
 Andreas Hindborg <a.hindborg@...sung.com>, Alice Ryhl
 <aliceryhl@...gle.com>, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, rust-for-linux@...r.kernel.org, Danilo
 Krummrich <dakr@...hat.com>
Cc: Jocelyn Falempe <jfalempe@...hat.com>
Subject: Re: [PATCH v6 2/4] drm/rect: Add drm_rect_overlap()

On Mon, 12 Aug 2024, Jocelyn Falempe <jfalempe@...hat.com> wrote:
> Check if two rectangles overlap.
> It's a bit similar to drm_rect_intersect() but this won't modify
> the rectangle.
> Simplifies a bit drm_panic.

Based on the name, I'd expect drm_rect_overlap() to return true for
*any* overlap, while this one seems to mean if one rectangle is
completely within another, with no adjacent borders.

I'd expect a drm_rect_overlap() to return true for this:

 +-------+
 |   +---+---+
 |   |       |
 +---+       |
     |       |
     +-------+

While this seems to be required instead:

 +-------+
 | +---+ |
 | |   | |
 | +---+ |
 +-------+


IOW, I find the name misleading.

BR,
Jani.


>
> Signed-off-by: Jocelyn Falempe <jfalempe@...hat.com>
> ---
>  drivers/gpu/drm/drm_panic.c |  3 +--
>  include/drm/drm_rect.h      | 15 +++++++++++++++
>  2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
> index 0a047152f88b8..59fba23e5fd7a 100644
> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
> @@ -529,8 +529,7 @@ static void draw_panic_static_user(struct drm_scanout_buffer *sb)
>  	/* Fill with the background color, and draw text on top */
>  	drm_panic_fill(sb, &r_screen, bg_color);
>  
> -	if ((r_msg.x1 >= logo_width || r_msg.y1 >= logo_height) &&
> -	    logo_width <= sb->width && logo_height <= sb->height) {
> +	if (!drm_rect_overlap(&r_logo, &r_msg)) {
>  		if (logo_mono)
>  			drm_panic_blit(sb, &r_logo, logo_mono->data, DIV_ROUND_UP(logo_width, 8),
>  				       fg_color);
> diff --git a/include/drm/drm_rect.h b/include/drm/drm_rect.h
> index 73fcb899a01da..7bafde747d560 100644
> --- a/include/drm/drm_rect.h
> +++ b/include/drm/drm_rect.h
> @@ -238,6 +238,21 @@ static inline void drm_rect_fp_to_int(struct drm_rect *dst,
>  		      drm_rect_height(src) >> 16);
>  }
>  
> +/**
> + * drm_rect_overlap - Check if two rectangles overlap
> + * @r1: first rectangle
> + * @r2: second rectangle
> + *
> + * RETURNS:
> + * %true if the rectangles overlap, %false otherwise.
> + */
> +static inline bool drm_rect_overlap(const struct drm_rect *r1,
> +				    const struct drm_rect *r2)
> +{
> +	return (r1->x2 > r2->x1 && r2->x2 > r1->x1 &&
> +		r1->y2 > r2->y1 && r2->y2 > r1->y1);
> +}
> +
>  bool drm_rect_intersect(struct drm_rect *r, const struct drm_rect *clip);
>  bool drm_rect_clip_scaled(struct drm_rect *src, struct drm_rect *dst,
>  			  const struct drm_rect *clip);

-- 
Jani Nikula, Intel