linux-kernel - [PATCH 4/5] drm: ssd130x: Reduce temporary buffer sizes

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Date:   Tue, 15 Mar 2022 12:07:06 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Noralf Trønnes <noralf@...nnes.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH 4/5] drm: ssd130x: Reduce temporary buffer sizes

ssd130x_clear_screen() allocates a temporary buffer sized to hold one
byte per pixel, while it only needs to hold one bit per pixel.

ssd130x_fb_blit_rect() allocates a temporary buffer sized to hold one
byte per pixel for the whole frame buffer, while it only needs to hold
one bit per pixel for the part that is to be updated.
Pass dst_pitch to drm_fb_xrgb8888_to_mono_reversed(), as we have already
calculated it anyway.

Fixes: a61732e808672cfa ("drm: Add driver for Solomon SSD130x OLED displays")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
 drivers/gpu/drm/solomon/ssd130x.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 7c99af4ce9dd4e5c..38b6c2c14f53644b 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -440,7 +440,8 @@ static void ssd130x_clear_screen(struct ssd130x_device *ssd130x)
 		.y2 = ssd130x->height,
 	};
 
-	buf = kcalloc(ssd130x->width, ssd130x->height, GFP_KERNEL);
+	buf = kcalloc(DIV_ROUND_UP(ssd130x->width, 8), ssd130x->height,
+		      GFP_KERNEL);
 	if (!buf)
 		return;
 
@@ -454,6 +455,7 @@ static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_m
 {
 	struct ssd130x_device *ssd130x = drm_to_ssd130x(fb->dev);
 	void *vmap = map->vaddr; /* TODO: Use mapping abstraction properly */
+	unsigned int dst_pitch;
 	int ret = 0;
 	u8 *buf = NULL;
 
@@ -461,11 +463,12 @@ static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_m
 	rect->y1 = round_down(rect->y1, 8);
 	rect->y2 = min_t(unsigned int, round_up(rect->y2, 8), ssd130x->height);
 
-	buf = kcalloc(fb->width, fb->height, GFP_KERNEL);
+	dst_pitch = DIV_ROUND_UP(drm_rect_width(rect), 8);
+	buf = kcalloc(dst_pitch, drm_rect_height(rect), GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	drm_fb_xrgb8888_to_mono(buf, 0, vmap, fb, rect);
+	drm_fb_xrgb8888_to_mono(buf, dst_pitch, vmap, fb, rect);
 
 	ssd130x_update_rect(ssd130x, buf, rect);
 
-- 
2.25.1