linux-kernel - [PATCH] drm/tiny: Refactor framebuffer's size calculation

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Message-ID: <20251020115803.192572-1-mehdi.benhadjkhelifa@gmail.com>
Date: Mon, 20 Oct 2025 12:57:23 +0100
From: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
To: lanzano.alex@...il.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	skhan@...uxfoundation.org,
	david.hunter.linux@...il.com,
	khalid@...nel.org,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
Subject: [PATCH] drm/tiny: Refactor framebuffer's size calculation

Use drm_format_info_min_pitch() to calculate the framebuffer line pitch
instead of directly multiplying width and height. This aligns with DRM
helpers for determining per-line byte size and avoids manual assumptions
about bytes per pixel.

Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
---
 drivers/gpu/drm/tiny/repaper.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tiny/repaper.c b/drivers/gpu/drm/tiny/repaper.c
index 4824f863fdba..aeff49bc6ba7 100644
--- a/drivers/gpu/drm/tiny/repaper.c
+++ b/drivers/gpu/drm/tiny/repaper.c
@@ -517,6 +517,8 @@ static int repaper_fb_dirty(struct drm_framebuffer *fb, const struct iosys_map *
 	unsigned int dst_pitch = 0;
 	struct iosys_map dst;
 	struct drm_rect clip;
+	const struct drm_format_info *info = fb->format;
+	size_t pitch;
 	int idx, ret = 0;
 	u8 *buf = NULL;
 
@@ -534,7 +536,9 @@ static int repaper_fb_dirty(struct drm_framebuffer *fb, const struct iosys_map *
 	DRM_DEBUG("Flushing [FB:%d] st=%ums\n", fb->base.id,
 		  epd->factored_stage_time);
 
-	buf = kmalloc(fb->width * fb->height / 8, GFP_KERNEL);
+	pitch = drm_format_info_min_pitch(info, 0, fb->width);
+
+	buf = kmalloc_array(fb->height, pitch, GFP_KERNEL);
 	if (!buf) {
 		ret = -ENOMEM;
 		goto out_exit;
-- 
2.51.1.dirty