diff options
author | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 12:17:53 -0700 |
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committer | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 15:44:42 -0700 |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/fb/ep93xx-fb.txt | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/fb/ep93xx-fb.txt')
-rw-r--r-- | kernel/Documentation/fb/ep93xx-fb.txt | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/kernel/Documentation/fb/ep93xx-fb.txt b/kernel/Documentation/fb/ep93xx-fb.txt new file mode 100644 index 000000000..5af1bd9ef --- /dev/null +++ b/kernel/Documentation/fb/ep93xx-fb.txt @@ -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. |