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>

1 files changed, 82 insertions, 0 deletions

diff --git a/drivers/media/video/ivtv/ivtvfb.c b/drivers/media/video/ivtv/ivtvfb.c
index 73be154f7f05..e8dbee443946 100644
--- 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,