linux-kernel - Re: [PATCH v7 2/4] drm/rect: Add drm_rect

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Message-ID: <d5de80ed-adc2-4307-bb57-27fc4e611100@redhat.com>
Date: Thu, 22 Aug 2024 15:12:08 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Thomas Zimmermann <tzimmermann@...e.de>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, 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>
Subject: Re: [PATCH v7 2/4] drm/rect: Add drm_rect_overlap()

On 22/08/2024 14:58, Thomas Zimmermann wrote:
> 
> 
> Am 22.08.24 um 09:33 schrieb Jocelyn Falempe:
>> 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.
>>
>> Signed-off-by: Jocelyn Falempe <jfalempe@...hat.com>
> 
> Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>
> 
> There's an optional comment further below.
> 
>> ---
>>
>> v7:
>>   * rename r1/r2 to a/b in drm_rect_overlap() (Jani Nikula)
>>
>>   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..46f09cf68458c 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
>> + * @a: first rectangle
>> + * @b: second rectangle
>> + *
>> + * RETURNS:
>> + * %true if the rectangles overlap, %false otherwise.
>> + */
>> +static inline bool drm_rect_overlap(const struct drm_rect *a,
>> +                    const struct drm_rect *b)
>> +{
>> +    return (a->x2 > b->x1 && b->x2 > a->x1 &&
>> +        a->y2 > b->y1 && b->y2 > a->y1);
> 
> I found this hard to understand. You may want to use the existing 
> _intersect helper
> 
> bool overlap(a, b)
> {
>    struct drm_rect tmp = *a
> 
>    return intersect(tmp, b);
> }

I considered this, but it creates an unused rect, and compute the 
intersection rectangle, which we are not interested in.
Even if the compiler may optimize and throw all this away, I prefer the 
more straightforward version.

Thanks for the review,

-- 

Jocelyn
> 
> Up to you.
> 
> Best regards
> Thomas
> 
>> +}
>> +
>>   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);
>