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246 lines
8.0 KiB
246 lines
8.0 KiB
From 370c8243ec8e7f3abd8171b7d2dde170f4c5e63a Mon Sep 17 00:00:00 2001
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From: Siarhei Siamashka <siarhei.siamashka@gmail.com>
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Date: Mon, 17 Jun 2013 16:00:25 +0300
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Subject: [PATCH 070/196] bcm2708_fb: DMA acceleration for fb_copyarea
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Based on http://www.raspberrypi.org/phpBB3/viewtopic.php?p=62425#p62425
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Also used Simon's dmaer_master module as a reference for tweaking DMA
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settings for better performance.
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For now busylooping only. IRQ support might be added later.
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With non-overclocked Raspberry Pi, the performance is ~360 MB/s
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for simple copy or ~260 MB/s for two-pass copy (used when dragging
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windows to the right).
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In the case of using DMA channel 0, the performance improves
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to ~440 MB/s.
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For comparison, VFP optimized CPU copy can only do ~114 MB/s in
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the same conditions (hindered by reading uncached source buffer).
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Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
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---
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drivers/video/bcm2708_fb.c | 162 ++++++++++++++++++++++++++++++++++++++++++++-
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1 file changed, 159 insertions(+), 3 deletions(-)
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diff --git a/drivers/video/bcm2708_fb.c b/drivers/video/bcm2708_fb.c
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index 08d9238..c10c5ee 100644
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--- a/drivers/video/bcm2708_fb.c
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+++ b/drivers/video/bcm2708_fb.c
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@@ -28,6 +28,7 @@
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#include <linux/printk.h>
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#include <linux/console.h>
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+#include <mach/dma.h>
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#include <mach/platform.h>
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#include <mach/vcio.h>
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@@ -63,6 +64,11 @@ struct bcm2708_fb {
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struct fbinfo_s *info;
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dma_addr_t dma;
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u32 cmap[16];
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+ int dma_chan;
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+ int dma_irq;
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+ void __iomem *dma_chan_base;
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+ void *cb_base; /* DMA control blocks */
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+ dma_addr_t cb_handle;
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};
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#define to_bcm2708(info) container_of(info, struct bcm2708_fb, fb)
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@@ -312,11 +318,133 @@ static void bcm2708_fb_fillrect(struct fb_info *info,
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cfb_fillrect(info, rect);
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}
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+/* A helper function for configuring dma control block */
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+static void set_dma_cb(struct bcm2708_dma_cb *cb,
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+ int burst_size,
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+ dma_addr_t dst,
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+ int dst_stride,
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+ dma_addr_t src,
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+ int src_stride,
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+ int w,
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+ int h)
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+{
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+ cb->info = BCM2708_DMA_BURST(burst_size) | BCM2708_DMA_S_WIDTH |
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+ BCM2708_DMA_S_INC | BCM2708_DMA_D_WIDTH |
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+ BCM2708_DMA_D_INC | BCM2708_DMA_TDMODE;
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+ cb->dst = dst;
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+ cb->src = src;
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+ /*
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+ * This is not really obvious from the DMA documentation,
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+ * but the top 16 bits must be programmmed to "height -1"
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+ * and not "height" in 2D mode.
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+ */
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+ cb->length = ((h - 1) << 16) | w;
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+ cb->stride = ((dst_stride - w) << 16) | (u16)(src_stride - w);
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+ cb->pad[0] = 0;
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+ cb->pad[1] = 0;
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+}
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+
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static void bcm2708_fb_copyarea(struct fb_info *info,
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const struct fb_copyarea *region)
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{
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- /*print_debug("bcm2708_fb_copyarea\n"); */
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- cfb_copyarea(info, region);
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+ struct bcm2708_fb *fb = to_bcm2708(info);
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+ struct bcm2708_dma_cb *cb = fb->cb_base;
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+ int bytes_per_pixel = (info->var.bits_per_pixel + 7) >> 3;
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+ /* Channel 0 supports larger bursts and is a bit faster */
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+ int burst_size = (fb->dma_chan == 0) ? 8 : 2;
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+
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+ /* Fallback to cfb_copyarea() if we don't like something */
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+ if (bytes_per_pixel > 4 ||
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+ info->var.xres > 1920 || info->var.yres > 1200 ||
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+ region->width <= 0 || region->width > info->var.xres ||
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+ region->height <= 0 || region->height > info->var.yres ||
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+ region->sx < 0 || region->sx >= info->var.xres ||
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+ region->sy < 0 || region->sy >= info->var.yres ||
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+ region->dx < 0 || region->dx >= info->var.xres ||
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+ region->dy < 0 || region->dy >= info->var.yres ||
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+ region->sx + region->width > info->var.xres ||
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+ region->dx + region->width > info->var.xres ||
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+ region->sy + region->height > info->var.yres ||
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+ region->dy + region->height > info->var.yres) {
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+ cfb_copyarea(info, region);
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+ return;
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+ }
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+
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+ if (region->dy == region->sy && region->dx > region->sx) {
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+ /*
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+ * A difficult case of overlapped copy. Because DMA can't
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+ * copy individual scanlines in backwards direction, we need
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+ * two-pass processing. We do it by programming a chain of dma
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+ * control blocks in the first 16K part of the buffer and use
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+ * the remaining 48K as the intermediate temporary scratch
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+ * buffer. The buffer size is sufficient to handle up to
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+ * 1920x1200 resolution at 32bpp pixel depth.
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+ */
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+ int y;
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+ dma_addr_t control_block_pa = fb->cb_handle;
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+ dma_addr_t scratchbuf = fb->cb_handle + 16 * 1024;
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+ int scanline_size = bytes_per_pixel * region->width;
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+ int scanlines_per_cb = (64 * 1024 - 16 * 1024) / scanline_size;
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+
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+ for (y = 0; y < region->height; y += scanlines_per_cb) {
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+ dma_addr_t src =
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+ fb->fb.fix.smem_start +
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+ bytes_per_pixel * region->sx +
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+ (region->sy + y) * fb->fb.fix.line_length;
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+ dma_addr_t dst =
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+ fb->fb.fix.smem_start +
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+ bytes_per_pixel * region->dx +
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+ (region->dy + y) * fb->fb.fix.line_length;
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+
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+ if (region->height - y < scanlines_per_cb)
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+ scanlines_per_cb = region->height - y;
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+
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+ set_dma_cb(cb, burst_size, scratchbuf, scanline_size,
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+ src, fb->fb.fix.line_length,
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+ scanline_size, scanlines_per_cb);
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+ control_block_pa += sizeof(struct bcm2708_dma_cb);
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+ cb->next = control_block_pa;
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+ cb++;
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+
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+ set_dma_cb(cb, burst_size, dst, fb->fb.fix.line_length,
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+ scratchbuf, scanline_size,
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+ scanline_size, scanlines_per_cb);
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+ control_block_pa += sizeof(struct bcm2708_dma_cb);
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+ cb->next = control_block_pa;
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+ cb++;
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+ }
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+ /* move the pointer back to the last dma control block */
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+ cb--;
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+ } else {
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+ /* A single dma control block is enough. */
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+ int sy, dy, stride;
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+ if (region->dy <= region->sy) {
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+ /* processing from top to bottom */
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+ dy = region->dy;
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+ sy = region->sy;
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+ stride = fb->fb.fix.line_length;
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+ } else {
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+ /* processing from bottom to top */
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+ dy = region->dy + region->height - 1;
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+ sy = region->sy + region->height - 1;
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+ stride = -fb->fb.fix.line_length;
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+ }
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+ set_dma_cb(cb, burst_size,
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+ fb->fb.fix.smem_start + dy * fb->fb.fix.line_length +
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+ bytes_per_pixel * region->dx,
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+ stride,
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+ fb->fb.fix.smem_start + sy * fb->fb.fix.line_length +
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+ bytes_per_pixel * region->sx,
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+ stride,
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+ region->width * bytes_per_pixel,
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+ region->height);
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+ }
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+
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+ /* end of dma control blocks chain */
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+ cb->next = 0;
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+
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+ bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
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+ bcm_dma_wait_idle(fb->dma_chan_base);
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}
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static void bcm2708_fb_imageblit(struct fb_info *info,
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@@ -359,7 +487,7 @@ static int bcm2708_fb_register(struct bcm2708_fb *fb)
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fb->dma = dma;
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}
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fb->fb.fbops = &bcm2708_fb_ops;
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- fb->fb.flags = FBINFO_FLAG_DEFAULT;
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+ fb->fb.flags = FBINFO_FLAG_DEFAULT | FBINFO_HWACCEL_COPYAREA;
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fb->fb.pseudo_palette = fb->cmap;
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strncpy(fb->fb.fix.id, bcm2708_name, sizeof(fb->fb.fix.id));
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@@ -424,6 +552,28 @@ static int bcm2708_fb_probe(struct platform_device *dev)
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}
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memset(fb, 0, sizeof(struct bcm2708_fb));
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+ fb->cb_base = dma_alloc_writecombine(&dev->dev, SZ_64K,
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+ &fb->cb_handle, GFP_KERNEL);
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+ if (!fb->cb_base) {
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+ dev_err(&dev->dev, "cannot allocate DMA CBs\n");
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+ ret = -ENOMEM;
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+ goto free_fb;
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+ }
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+
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+ pr_info("BCM2708FB: allocated DMA memory %08x\n",
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+ fb->cb_handle);
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+
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+ ret = bcm_dma_chan_alloc(BCM_DMA_FEATURE_BULK,
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+ &fb->dma_chan_base, &fb->dma_irq);
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+ if (ret < 0) {
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+ dev_err(&dev->dev, "couldn't allocate a DMA channel\n");
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+ goto free_cb;
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+ }
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+ fb->dma_chan = ret;
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+
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+ pr_info("BCM2708FB: allocated DMA channel %d @ %p\n",
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+ fb->dma_chan, fb->dma_chan_base);
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+
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fb->dev = dev;
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ret = bcm2708_fb_register(fb);
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@@ -432,6 +582,9 @@ static int bcm2708_fb_probe(struct platform_device *dev)
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goto out;
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}
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+free_cb:
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+ dma_free_writecombine(&dev->dev, SZ_64K, fb->cb_base, fb->cb_handle);
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+free_fb:
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kfree(fb);
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free_region:
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dev_err(&dev->dev, "probe failed, err %d\n", ret);
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@@ -449,6 +602,9 @@ static int bcm2708_fb_remove(struct platform_device *dev)
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iounmap(fb->fb.screen_base);
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unregister_framebuffer(&fb->fb);
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+ dma_free_writecombine(&dev->dev, SZ_64K, fb->cb_base, fb->cb_handle);
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+ bcm_dma_chan_free(fb->dma_chan);
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+
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dma_free_coherent(NULL, PAGE_ALIGN(sizeof(*fb->info)), (void *)fb->info,
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fb->dma);
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kfree(fb);
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--
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1.9.1
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