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User-space applications can use the VIDIOC_REQBUFS ioctl to determine if a memory mapped, user pointer or DMABUF based I/O is supported by a driver. For example, GStreamer attempts to determine the I/O methods supported by the driver by doing many VIDIOC_REQBUFS ioctl calls with different memory types and count 0. And then the real VIDIOC_REQBUFS call with count == n is be made to allocate the buffers. But for count 0, the driver not only frees the buffers but also clears the format set before with VIDIOC_S_FMT. This is a problem since STREAMON fails if a format isn't set but GStreamer first sets a format and then tries to determine the supported I/O methods, so the format will be cleared on REQBUFS(0), before the call to STREAMON. To avoid this issue, only free the buffers on VIDIOC_REQBUFS(0) but don't clear the format. Since is completely valid to set the format and then do different calls to REQBUFS before a call to STREAMON. Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> |
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| .. | ||
| cec | ||
| common | ||
| dvb-core | ||
| dvb-frontends | ||
| firewire | ||
| i2c | ||
| mmc | ||
| pci | ||
| platform | ||
| radio | ||
| rc | ||
| spi | ||
| tuners | ||
| usb | ||
| v4l2-core | ||
| cec-edid.c | ||
| Kconfig | ||
| Makefile | ||
| media-device.c | ||
| media-devnode.c | ||
| media-entity.c | ||