ARM: clcd: add method for describing display capabilities
The ARM CLCD PL110 controller in TFT mode provides two output formats
based on whether the controller is in 24bpp mode or not - either 5551
or 888. PL111 augments this with a 444 and 565 modes.
Some implementations provide an external MUX on the PL110 output to
reassign the bits to achieve 565 mode.
Provide a system of capability flags to allow the CLCD driver to work
out what is supported by each panel and board, and therefore which
display formats are permitted.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/video/amba-clcd.c b/drivers/video/amba-clcd.c
index aedbb34..8bd3706 100644
--- a/drivers/video/amba-clcd.c
+++ b/drivers/video/amba-clcd.c
@@ -120,8 +120,23 @@
static int
clcdfb_set_bitfields(struct clcd_fb *fb, struct fb_var_screeninfo *var)
{
+ u32 caps;
int ret = 0;
+ if (fb->panel->caps && fb->board->caps)
+ caps = fb->panel->caps & fb->board->caps;
+ else {
+ /* Old way of specifying what can be used */
+ caps = fb->panel->cntl & CNTL_BGR ?
+ CLCD_CAP_BGR : CLCD_CAP_RGB;
+ /* But mask out 444 modes as they weren't supported */
+ caps &= ~CLCD_CAP_444;
+ }
+
+ /* Only TFT panels can do RGB888/BGR888 */
+ if (!(fb->panel->cntl & CNTL_LCDTFT))
+ caps &= ~CLCD_CAP_888;
+
memset(&var->transp, 0, sizeof(var->transp));
var->red.msb_right = 0;
@@ -133,6 +148,13 @@
case 2:
case 4:
case 8:
+ /* If we can't do 5551, reject */
+ caps &= CLCD_CAP_5551;
+ if (!caps) {
+ ret = -EINVAL;
+ break;
+ }
+
var->red.length = var->bits_per_pixel;
var->red.offset = 0;
var->green.length = var->bits_per_pixel;
@@ -140,23 +162,61 @@
var->blue.length = var->bits_per_pixel;
var->blue.offset = 0;
break;
+
case 16:
- var->red.length = 5;
- var->blue.length = 5;
- /*
- * Green length can be 5 or 6 depending whether
- * we're operating in RGB555 or RGB565 mode.
- */
- if (var->green.length != 5 && var->green.length != 6)
- var->green.length = 6;
- break;
- case 32:
- if (fb->panel->cntl & CNTL_LCDTFT) {
- var->red.length = 8;
- var->green.length = 8;
- var->blue.length = 8;
+ /* If we can't do 444, 5551 or 565, reject */
+ if (!(caps & (CLCD_CAP_444 | CLCD_CAP_5551 | CLCD_CAP_565))) {
+ ret = -EINVAL;
break;
}
+
+ /*
+ * Green length can be 4, 5 or 6 depending whether
+ * we're operating in 444, 5551 or 565 mode.
+ */
+ if (var->green.length == 4 && caps & CLCD_CAP_444)
+ caps &= CLCD_CAP_444;
+ if (var->green.length == 5 && caps & CLCD_CAP_5551)
+ caps &= CLCD_CAP_5551;
+ else if (var->green.length == 6 && caps & CLCD_CAP_565)
+ caps &= CLCD_CAP_565;
+ else {
+ /*
+ * PL110 officially only supports RGB555,
+ * but may be wired up to allow RGB565.
+ */
+ if (caps & CLCD_CAP_565) {
+ var->green.length = 6;
+ caps &= CLCD_CAP_565;
+ } else if (caps & CLCD_CAP_5551) {
+ var->green.length = 5;
+ caps &= CLCD_CAP_5551;
+ } else {
+ var->green.length = 4;
+ caps &= CLCD_CAP_444;
+ }
+ }
+
+ if (var->green.length >= 5) {
+ var->red.length = 5;
+ var->blue.length = 5;
+ } else {
+ var->red.length = 4;
+ var->blue.length = 4;
+ }
+ break;
+ case 32:
+ /* If we can't do 888, reject */
+ caps &= CLCD_CAP_888;
+ if (!caps) {
+ ret = -EINVAL;
+ break;
+ }
+
+ var->red.length = 8;
+ var->green.length = 8;
+ var->blue.length = 8;
+ break;
default:
ret = -EINVAL;
break;
@@ -168,7 +228,20 @@
* the bitfield length defined above.
*/
if (ret == 0 && var->bits_per_pixel >= 16) {
- if (fb->panel->cntl & CNTL_BGR) {
+ bool bgr, rgb;
+
+ bgr = caps & CLCD_CAP_BGR && var->blue.offset == 0;
+ rgb = caps & CLCD_CAP_RGB && var->red.offset == 0;
+
+ if (!bgr && !rgb)
+ /*
+ * The requested format was not possible, try just
+ * our capabilities. One of BGR or RGB must be
+ * supported.
+ */
+ bgr = caps & CLCD_CAP_BGR;
+
+ if (bgr) {
var->blue.offset = 0;
var->green.offset = var->blue.offset + var->blue.length;
var->red.offset = var->green.offset + var->green.length;