drm/ssd130x: Don't allocate buffers on each plane update

The resolutions for these panels are fixed and defined in the Device Tree,
so there's no point to allocate the buffers on each plane update and that
can just be done once.

Let's do the allocation and free on the encoder enable and disable helpers
since that's where others initialization and teardown operations are done.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230609170941.1150941-5-javierm@redhat.com

drivers/gpu/drm/solomon/ssd130x.c

@@ -146,6 +146,31 @@ static inline struct ssd130x_device *drm_to_ssd130x(struct drm_device *drm)
 	return container_of(drm, struct ssd130x_device, drm);
 }
 
+static int ssd130x_buf_alloc(struct ssd130x_device *ssd130x)
+{
+	unsigned int page_height = ssd130x->device_info->page_height;
+	unsigned int pages = DIV_ROUND_UP(ssd130x->height, page_height);
+
+	ssd130x->buffer = kcalloc(DIV_ROUND_UP(ssd130x->width, 8),
+				  ssd130x->height, GFP_KERNEL);
+	if (!ssd130x->buffer)
+		return -ENOMEM;
+
+	ssd130x->data_array = kcalloc(ssd130x->width, pages, GFP_KERNEL);
+	if (!ssd130x->data_array) {
+		kfree(ssd130x->buffer);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void ssd130x_buf_free(struct ssd130x_device *ssd130x)
+{
+	kfree(ssd130x->data_array);
+	kfree(ssd130x->buffer);
+}
+
 /*
  * Helper to write data (SSD130X_DATA) to the device.
  */
@@ -434,11 +459,12 @@ static int ssd130x_init(struct ssd130x_device *ssd130x)
 				 SSD130X_SET_ADDRESS_MODE_HORIZONTAL);
 }
 
-static int ssd130x_update_rect(struct ssd130x_device *ssd130x, u8 *buf,
-			       struct drm_rect *rect)
+static int ssd130x_update_rect(struct ssd130x_device *ssd130x, struct drm_rect *rect)
 {
 	unsigned int x = rect->x1;
 	unsigned int y = rect->y1;
+	u8 *buf = ssd130x->buffer;
+	u8 *data_array = ssd130x->data_array;
 	unsigned int width = drm_rect_width(rect);
 	unsigned int height = drm_rect_height(rect);
 	unsigned int line_length = DIV_ROUND_UP(width, 8);
@@ -447,14 +473,9 @@ static int ssd130x_update_rect(struct ssd130x_device *ssd130x, u8 *buf,
 	struct drm_device *drm = &ssd130x->drm;
 	u32 array_idx = 0;
 	int ret, i, j, k;
-	u8 *data_array = NULL;
 
 	drm_WARN_ONCE(drm, y % 8 != 0, "y must be aligned to screen page\n");
 
-	data_array = kcalloc(width, pages, GFP_KERNEL);
-	if (!data_array)
-		return -ENOMEM;
-
 	/*
 	 * The screen is divided in pages, each having a height of 8
 	 * pixels, and the width of the screen. When sending a byte of
@@ -488,11 +509,11 @@ static int ssd130x_update_rect(struct ssd130x_device *ssd130x, u8 *buf,
 		/* Set address range for horizontal addressing mode */
 		ret = ssd130x_set_col_range(ssd130x, ssd130x->col_offset + x, width);
 		if (ret < 0)
-			goto out_free;
+			return ret;
 
 		ret = ssd130x_set_page_range(ssd130x, ssd130x->page_offset + y / 8, pages);
 		if (ret < 0)
-			goto out_free;
+			return ret;
 	}
 
 	for (i = 0; i < pages; i++) {
@@ -522,11 +543,11 @@ static int ssd130x_update_rect(struct ssd130x_device *ssd130x, u8 *buf,
 						   ssd130x->page_offset + i,
 						   ssd130x->col_offset + x);
 			if (ret < 0)
-				goto out_free;
+				return ret;
 
 			ret = ssd130x_write_data(ssd130x, data_array, width);
 			if (ret < 0)
-				goto out_free;
+				return ret;
 
 			array_idx = 0;
 		}
@@ -536,14 +557,11 @@ static int ssd130x_update_rect(struct ssd130x_device *ssd130x, u8 *buf,
 	if (!ssd130x->page_address_mode)
 		ret = ssd130x_write_data(ssd130x, data_array, width * pages);
 
-out_free:
-	kfree(data_array);
 	return ret;
 }
 
 static void ssd130x_clear_screen(struct ssd130x_device *ssd130x)
 {
-	u8 *buf = NULL;
 	struct drm_rect fullscreen = {
 		.x1 = 0,
 		.x2 = ssd130x->width,
@@ -551,14 +569,7 @@ static void ssd130x_clear_screen(struct ssd130x_device *ssd130x)
 		.y2 = ssd130x->height,
 	};
 
-	buf = kcalloc(DIV_ROUND_UP(ssd130x->width, 8), ssd130x->height,
-		      GFP_KERNEL);
-	if (!buf)
-		return;
-
-	ssd130x_update_rect(ssd130x, buf, &fullscreen);
-
-	kfree(buf);
+	ssd130x_update_rect(ssd130x, &fullscreen);
 }
 
 static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_map *vmap,
@@ -569,30 +580,27 @@ static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_m
 	struct iosys_map dst;
 	unsigned int dst_pitch;
 	int ret = 0;
-	u8 *buf = NULL;
+	u8 *buf = ssd130x->buffer;
+
+	if (!buf)
+		return 0;
 
 	/* Align y to display page boundaries */
 	rect->y1 = round_down(rect->y1, page_height);
 	rect->y2 = min_t(unsigned int, round_up(rect->y2, page_height), ssd130x->height);
 
 	dst_pitch = DIV_ROUND_UP(drm_rect_width(rect), page_height);
-	buf = kcalloc(dst_pitch, drm_rect_height(rect), GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
 
 	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
 	if (ret)
-		goto out_free;
+		return ret;
 
 	iosys_map_set_vaddr(&dst, buf);
 	drm_fb_xrgb8888_to_mono(&dst, &dst_pitch, vmap, fb, rect);
 
 	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
 
-	ssd130x_update_rect(ssd130x, buf, rect);
-
-out_free:
-	kfree(buf);
+	ssd130x_update_rect(ssd130x, rect);
 
 	return ret;
 }
@@ -701,14 +709,22 @@ static void ssd130x_encoder_helper_atomic_enable(struct drm_encoder *encoder,
 		return;
 
 	ret = ssd130x_init(ssd130x);
-	if (ret) {
-		ssd130x_power_off(ssd130x);
-		return;
-	}
+	if (ret)
+		goto power_off;
+
+	ret = ssd130x_buf_alloc(ssd130x);
+	if (ret)
+		goto power_off;
 
 	ssd130x_write_cmd(ssd130x, 1, SSD130X_DISPLAY_ON);
 
 	backlight_enable(ssd130x->bl_dev);
+
+	return;
+
+power_off:
+	ssd130x_power_off(ssd130x);
+	return;
 }
 
 static void ssd130x_encoder_helper_atomic_disable(struct drm_encoder *encoder,
@@ -721,6 +737,8 @@ static void ssd130x_encoder_helper_atomic_disable(struct drm_encoder *encoder,
 
 	ssd130x_write_cmd(ssd130x, 1, SSD130X_DISPLAY_OFF);
 
+	ssd130x_buf_free(ssd130x);
+
 	ssd130x_power_off(ssd130x);
 }
 

drivers/gpu/drm/solomon/ssd130x.h

@@ -89,6 +89,9 @@ struct ssd130x_device {
 	u8 col_end;
 	u8 page_start;
 	u8 page_end;
+
+	u8 *buffer;
+	u8 *data_array;
 };
 
 extern const struct ssd130x_deviceinfo ssd130x_variants[];