ep93xx video driver
EP93xx video driver plus documentation. Signed-off-by: Ryan Mallon <ryan@bluewatersys.com> Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com> Cc: Daniele Venzano <linux@brownhat.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Krzysztof Helt <krzysztof.h1@poczta.fm> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ryan Mallon
committed by
Linus Torvalds
Linus Torvalds
parent
c6012189a4
commit
88017bda96
135
Documentation/fb/ep93xx-fb.txt
Normal file
135
Documentation/fb/ep93xx-fb.txt
Normal file
@@ -0,0 +1,135 @@
|
||||
================================
|
||||
Driver for EP93xx LCD controller
|
||||
================================
|
||||
|
||||
The EP93xx LCD controller can drive both standard desktop monitors and
|
||||
embedded LCD displays. If you have a standard desktop monitor then you
|
||||
can use the standard Linux video mode database. In your board file:
|
||||
|
||||
static struct ep93xxfb_mach_info some_board_fb_info = {
|
||||
.num_modes = EP93XXFB_USE_MODEDB,
|
||||
.bpp = 16,
|
||||
};
|
||||
|
||||
If you have an embedded LCD display then you need to define a video
|
||||
mode for it as follows:
|
||||
|
||||
static struct fb_videomode some_board_video_modes[] = {
|
||||
{
|
||||
.name = "some_lcd_name",
|
||||
/* Pixel clock, porches, etc */
|
||||
},
|
||||
};
|
||||
|
||||
Note that the pixel clock value is in pico-seconds. You can use the
|
||||
KHZ2PICOS macro to convert the pixel clock value. Most other values
|
||||
are in pixel clocks. See Documentation/fb/framebuffer.txt for further
|
||||
details.
|
||||
|
||||
The ep93xxfb_mach_info structure for your board should look like the
|
||||
following:
|
||||
|
||||
static struct ep93xxfb_mach_info some_board_fb_info = {
|
||||
.num_modes = ARRAY_SIZE(some_board_video_modes),
|
||||
.modes = some_board_video_modes,
|
||||
.default_mode = &some_board_video_modes[0],
|
||||
.bpp = 16,
|
||||
};
|
||||
|
||||
The framebuffer device can be registered by adding the following to
|
||||
your board initialisation function:
|
||||
|
||||
ep93xx_register_fb(&some_board_fb_info);
|
||||
|
||||
=====================
|
||||
Video Attribute Flags
|
||||
=====================
|
||||
|
||||
The ep93xxfb_mach_info structure has a flags field which can be used
|
||||
to configure the controller. The video attributes flags are fully
|
||||
documented in section 7 of the EP93xx users' guide. The following
|
||||
flags are available:
|
||||
|
||||
EP93XXFB_PCLK_FALLING Clock data on the falling edge of the
|
||||
pixel clock. The default is to clock
|
||||
data on the rising edge.
|
||||
|
||||
EP93XXFB_SYNC_BLANK_HIGH Blank signal is active high. By
|
||||
default the blank signal is active low.
|
||||
|
||||
EP93XXFB_SYNC_HORIZ_HIGH Horizontal sync is active high. By
|
||||
default the horizontal sync is active low.
|
||||
|
||||
EP93XXFB_SYNC_VERT_HIGH Vertical sync is active high. By
|
||||
default the vertical sync is active high.
|
||||
|
||||
The physical address of the framebuffer can be controlled using the
|
||||
following flags:
|
||||
|
||||
EP93XXFB_USE_SDCSN0 Use SDCSn[0] for the framebuffer. This
|
||||
is the default setting.
|
||||
|
||||
EP93XXFB_USE_SDCSN1 Use SDCSn[1] for the framebuffer.
|
||||
|
||||
EP93XXFB_USE_SDCSN2 Use SDCSn[2] for the framebuffer.
|
||||
|
||||
EP93XXFB_USE_SDCSN3 Use SDCSn[3] for the framebuffer.
|
||||
|
||||
==================
|
||||
Platform callbacks
|
||||
==================
|
||||
|
||||
The EP93xx framebuffer driver supports three optional platform
|
||||
callbacks: setup, teardown and blank. The setup and teardown functions
|
||||
are called when the framebuffer driver is installed and removed
|
||||
respectively. The blank function is called whenever the display is
|
||||
blanked or unblanked.
|
||||
|
||||
The setup and teardown devices pass the platform_device structure as
|
||||
an argument. The fb_info and ep93xxfb_mach_info structures can be
|
||||
obtained as follows:
|
||||
|
||||
static int some_board_fb_setup(struct platform_device *pdev)
|
||||
{
|
||||
struct ep93xxfb_mach_info *mach_info = pdev->dev.platform_data;
|
||||
struct fb_info *fb_info = platform_get_drvdata(pdev);
|
||||
|
||||
/* Board specific framebuffer setup */
|
||||
}
|
||||
|
||||
======================
|
||||
Setting the video mode
|
||||
======================
|
||||
|
||||
The video mode is set using the following syntax:
|
||||
|
||||
video=XRESxYRES[-BPP][@REFRESH]
|
||||
|
||||
If the EP93xx video driver is built-in then the video mode is set on
|
||||
the Linux kernel command line, for example:
|
||||
|
||||
video=ep93xx-fb:800x600-16@60
|
||||
|
||||
If the EP93xx video driver is built as a module then the video mode is
|
||||
set when the module is installed:
|
||||
|
||||
modprobe ep93xx-fb video=320x240
|
||||
|
||||
==============
|
||||
Screenpage bug
|
||||
==============
|
||||
|
||||
At least on the EP9315 there is a silicon bug which causes bit 27 of
|
||||
the VIDSCRNPAGE (framebuffer physical offset) to be tied low. There is
|
||||
an unofficial errata for this bug at:
|
||||
http://marc.info/?l=linux-arm-kernel&m=110061245502000&w=2
|
||||
|
||||
By default the EP93xx framebuffer driver checks if the allocated physical
|
||||
address has bit 27 set. If it does, then the memory is freed and an
|
||||
error is returned. The check can be disabled by adding the following
|
||||
option when loading the driver:
|
||||
|
||||
ep93xx-fb.check_screenpage_bug=0
|
||||
|
||||
In some cases it may be possible to reconfigure your SDRAM layout to
|
||||
avoid this bug. See section 13 of the EP93xx users' guide for details.
|
||||
Reference in New Issue
Block a user