Chapter 8
ELCDIF Frame Buffer Driver
8.1 Introduction
The ELCDIF frame buffer driver is designed using the Linux kernel frame buffer driver
framework. It implements the platform driver for a frame buffer device. The
implementation uses the ELCDIF API for generic LCD low-level operations. The
ELCDIF API is also defined in the ELCDIF frame buffer driver to realize low level
hardware control. Only DOTCLK mode of the ELCDIF API is tested, so theoretically the
ELCDIF frame buffer driver can work with a sync LCD panel driver to support a frame
buffer device. The sync LCD driver is organized in a flexible and extensible manner and
is abstracted from any specific sync LCD panel support. To support another sync LCD
panel, the user can write a sync LCD driver by referring to the existing one.
8.2 Hardware Operation
For detailed hardware operation, please refer to the i.MX 6SoloLite Multimedia
Applications Processor Reference Manual.
8.3 Software Operation
A frame buffer device is a memory device similar to /dev/mem and it has the same
features. It can be read from, written to, or some location in it can be sought and maped
using mmap(). The difference is that the memory that appears is not the whole memory,
but only the frame buffer of the video hardware. The device is accessed through special
device nodes, usually located in the /dev directory, /dev/fb*. /dev/fb* also has several
IOCTLs which act on it and through which information about the hardware can be
queried and set. The color map handling operates through IOCTLs as well. See linux/fb.h
for more information on which IOCTLs there are and which data structures they use.
i.MX 6SoloLite Linux Reference Manual, Rev. L3.0.35_4.1.0, 09/2013
Freescale Semiconductor, Inc.
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