V4L/DVB (7886): ivtvfb: Use DMA for write()

write() operations to the ivtv framebuffer will now attempt to use DMA if the
amount of data to copy is >= 4096 bytes. This change effectively depreciates
the need for the proprietary IVTVFB_IOC_DMA_FRAME ioctl since a write() of
sufficient size will do the same thing.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

diff --git a/drivers/media/video/ivtv/ivtvfb.c b/drivers/media/video/ivtv/ivtvfb.c
index 73be154f7f0520666c977140bf8a3047b72b7061..e8dbee4439460ecb9c0ca2714b06e78f04220f72 100644 (file)
--- a/drivers/media/video/ivtv/ivtvfb.c
+++ b/drivers/media/video/ivtv/ivtvfb.c
@@ -367,6 +367,87 @@ static int ivtvfb_prep_frame(struct ivtv *itv, int cmd, void __user *source,
        return ivtvfb_prep_dec_dma_to_device(itv, dest_offset, source, count);
 }
 
+static ssize_t ivtvfb_write(struct fb_info *info, const char __user *buf,
+                    size_t count, loff_t *ppos)
+{
+       unsigned long p = *ppos;
+       void *dst;
+       int err = 0;
+       unsigned long total_size;
+       struct ivtv *itv = (struct ivtv *) info->par;
+       unsigned long dma_offset =
+                       IVTV_DECODER_OFFSET + itv->osd_info->video_rbase;
+       unsigned long dma_size;
+       u16 lead = 0, tail = 0;
+
+       if (info->state != FBINFO_STATE_RUNNING)
+               return -EPERM;
+
+       total_size = info->screen_size;
+
+       if (total_size == 0)
+               total_size = info->fix.smem_len;
+
+       if (p > total_size)
+               return -EFBIG;
+
+       if (count > total_size) {
+               err = -EFBIG;
+               count = total_size;
+       }
+
+       if (count + p > total_size) {
+               if (!err)
+                       err = -ENOSPC;
+
+               count = total_size - p;
+       }
+
+       dst = (void __force *) (info->screen_base + p);
+
+       if (info->fbops->fb_sync)
+               info->fbops->fb_sync(info);
+
+       if (!access_ok(VERIFY_READ, buf, count)) {
+               IVTVFB_WARN("Invalid userspace pointer 0x%08lx\n",
+                       (unsigned long)buf);
+               err = -EFAULT;
+       }
+
+       if (!err) {
+               /* If transfer size > threshold and both src/dst
+               addresses are aligned, use DMA */
+               if (count >= 4096 && ((u32)buf & 3) == ((u32)dst & 3)) {
+                       /* Odd address = can't DMA. Align */
+                       if ((u32)dst & 3) {
+                               lead = 4 - ((u32)dst & 3);
+                               memcpy(dst, buf, lead);
+                               buf += lead;
+                               dst += lead;
+                       }
+                       /* DMA resolution is 32 bits */
+                       if ((count - lead) & 3)
+                               tail = (count - lead) & 3;
+                       /* DMA the data */
+                       dma_size = count - lead - tail;
+                       err = ivtvfb_prep_dec_dma_to_device(itv,
+                              p + lead + dma_offset, (void *)buf, dma_size);
+                       dst += dma_size;
+                       buf += dma_size;
+                       /* Copy any leftover data */
+                       if (tail)
+                               memcpy(dst, buf, tail);
+               } else {
+                       memcpy(dst, buf, count);
+               }
+       }
+
+       if  (!err)
+               *ppos += count;
+
+       return (err) ? err : count;
+}
+
 static int ivtvfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
 {
        DEFINE_WAIT(wait);
@@ -824,6 +905,7 @@ static int ivtvfb_blank(int blank_mode, struct fb_info *info)
 
 static struct fb_ops ivtvfb_ops = {
        .owner = THIS_MODULE,
+       .fb_write       = ivtvfb_write,
        .fb_check_var   = ivtvfb_check_var,
        .fb_set_par     = ivtvfb_set_par,
        .fb_setcolreg   = ivtvfb_setcolreg,