1 ================================
2 Driver for EP93xx LCD controller
3 ================================
4
5 The EP93xx LCD controller can drive both stand
6 embedded LCD displays. If you have a standard
7 can use the standard Linux video mode database
8
9 static struct ep93xxfb_mach_info some_
10 .num_modes = EP93XXFB_USE
11 .bpp = 16,
12 };
13
14 If you have an embedded LCD display then you n
15 mode for it as follows::
16
17 static struct fb_videomode some_board_
18 {
19 .name = "som
20 /* Pixel clock, porche
21 },
22 };
23
24 Note that the pixel clock value is in pico-sec
25 KHZ2PICOS macro to convert the pixel clock val
26 are in pixel clocks. See Documentation/fb/fram
27 details.
28
29 The ep93xxfb_mach_info structure for your boar
30 following::
31
32 static struct ep93xxfb_mach_info some_
33 .num_modes = ARRAY_SIZE(s
34 .modes = some_board_v
35 .default_mode = &some_board_
36 .bpp = 16,
37 };
38
39 The framebuffer device can be registered by ad
40 your board initialisation function::
41
42 ep93xx_register_fb(&some_board_fb_info
43
44 =====================
45 Video Attribute Flags
46 =====================
47
48 The ep93xxfb_mach_info structure has a flags f
49 to configure the controller. The video attribu
50 documented in section 7 of the EP93xx users' g
51 flags are available:
52
53 =============================== ==============
54 EP93XXFB_PCLK_FALLING Clock data on
55 pixel clock. T
56 data on the ri
57
58 EP93XXFB_SYNC_BLANK_HIGH Blank signal i
59 default the bl
60
61 EP93XXFB_SYNC_HORIZ_HIGH Horizontal syn
62 default the ho
63
64 EP93XXFB_SYNC_VERT_HIGH Vertical sync
65 default the ve
66 =============================== ==============
67
68 The physical address of the framebuffer can be
69 following flags:
70
71 =============================== ==============
72 EP93XXFB_USE_SDCSN0 Use SDCSn[0] f
73 is the default
74
75 EP93XXFB_USE_SDCSN1 Use SDCSn[1] f
76
77 EP93XXFB_USE_SDCSN2 Use SDCSn[2] f
78
79 EP93XXFB_USE_SDCSN3 Use SDCSn[3] f
80 =============================== ==============
81
82 ==================
83 Platform callbacks
84 ==================
85
86 The EP93xx framebuffer driver supports three o
87 callbacks: setup, teardown and blank. The setu
88 are called when the framebuffer driver is inst
89 respectively. The blank function is called whe
90 blanked or unblanked.
91
92 The setup and teardown devices pass the platfo
93 an argument. The fb_info and ep93xxfb_mach_inf
94 obtained as follows::
95
96 static int some_board_fb_setup(struct
97 {
98 struct ep93xxfb_mach_info *mac
99 struct fb_info *fb_info = plat
100
101 /* Board specific framebuffer
102 }
103
104 ======================
105 Setting the video mode
106 ======================
107
108 The video mode is set using the following synt
109
110 video=XRESxYRES[-BPP][@REFRESH]
111
112 If the EP93xx video driver is built-in then th
113 the Linux kernel command line, for example::
114
115 video=ep93xx-fb:800x600-16@60
116
117 If the EP93xx video driver is built as a modul
118 set when the module is installed::
119
120 modprobe ep93xx-fb video=320x240
121
122 ==============
123 Screenpage bug
124 ==============
125
126 At least on the EP9315 there is a silicon bug
127 the VIDSCRNPAGE (framebuffer physical offset)
128 an unofficial errata for this bug at::
129
130 https://marc.info/?l=linux-arm-kernel&
131
132 By default the EP93xx framebuffer driver check
133 address has bit 27 set. If it does, then the m
134 error is returned. The check can be disabled b
135 option when loading the driver::
136
137 ep93xx-fb.check_screenpage_bug=0
138
139 In some cases it may be possible to reconfigur
140 avoid this bug. See section 13 of the EP93xx u
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