staging: drm/imx: also allow to allocate only 2 DMFC slots for DP full plane

Connecting a 320x240 parallel display on i.MX6 resulted in an invalid DRDY
signal because the DC would not receive NL/EOL events on every line.
Reducing the allocated DMFC space from 4 slots (256 * 128-bit) to 2 slots
(128 * 128-bit) solved the problem.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c b/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c
index 2e97c33..98070dd 100644 (file)
--- a/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c
+++ b/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c
@@ -307,13 +307,13 @@ int ipu_dmfc_alloc_bandwidth(struct dmfc_channel *dmfc,
                goto out;
        }
 
-       /* Always allocate at least 128*4 bytes (2 slots) */
-       if (slots < 2)
-               slots = 2;
-
        /* For the MEM_BG channel, first try to allocate twice the slots */
        if (dmfc->data->ipu_channel == IPUV3_CHANNEL_MEM_BG_SYNC)
                segment = dmfc_find_slots(priv, slots * 2);
+       else if (slots < 2)
+               /* Always allocate at least 128*4 bytes (2 slots) */
+               slots = 2;
+
        if (segment >= 0)
                slots *= 2;
        else