Add some comments about the format of the HWC32 cursor colour format.
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/armada/armada_crtc.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/armada/armada_crtc.c b/drivers/gpu/drm/armada/armada_crtc.c
index 5991feb1bcc9..e81e57823b66 100644
--- a/drivers/gpu/drm/armada/armada_crtc.c
+++ b/drivers/gpu/drm/armada/armada_crtc.c
@@ -515,6 +515,13 @@ static void armada_load_cursor_argb(void __iomem *base, uint32_t *pix,
for (x = 0; x < width; x++, p++) {
uint32_t val = *p;
+ /*
+ * In "ARGB888" (HWC32) mode, writing to the SRAM
+ * requires these bits to contain:
+ * 31:24 = alpha 23:16 = blue 15:8 = green 7:0 = red
+ * So, it's actually ABGR8888. This is independent
+ * of the SWAPRB bits in DMA control register 0.
+ */
val = (val & 0xff00ff00) |
(val & 0x000000ff) << 16 |
(val & 0x00ff0000) >> 16;
--
2.7.4
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