imx6: fix DMA transaction errors

Following errors were seen in the past on imx6 when using serial:

[ 22.617622] imx-uart 2020000.serial: DMA transaction error.
[ 22.623228] imx-uart 2020000.serial: DMA transaction error.
[ 22.628826] imx-uart 2020000.serial: DMA transaction error.
[ 22.648951] imx-uart 2020000.serial: DMA transaction error.
[ 22.654558] imx-uart 2020000.serial: DMA transaction error.
[ 22.660156] imx-uart 2020000.serial: DMA transaction error.

Which is the reason why DMA for the serial ports
got disabled in commits:

efb362cd93b0 ("imx6: disable dma on uart")
3b4241071dd4 ("imx6: disable UART dma")

As indicated on mailinglist discussion, the cause seems to be
the usage of very old SDMA firmware which is present in the soc:

[    0.624302] imx-sdma 20ec000.sdma: Direct firmware load for imx/sdma/sdma-imx6q.bin failed with error -2
[    0.624318] imx-sdma 20ec000.sdma: Falling back to user helper
[   64.531607] imx-sdma 20ec000.sdma: external firmware not found, using ROM firmware

This patch adds the new firmware binary. (2196 bytes)

It is required to embed the binary into the kernel image, as it
gets loaded very early in the boot process where the rootfs is not
available yet:

[    0.622966] imx-sdma 20ec000.sdma: loaded firmware 3.3

Extended testing shows that the DMA errors are not seen anymore
when using this newer firmware version.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
(backported from 74738c4b8057cbc155c3c67a1b372b1eec2e7ecc)

diff --git a/target/linux/imx6/config-4.14 b/target/linux/imx6/config-4.14
index 929f863d8a77c1e03f9c77d4b615616092fecb61..6f7acfd129048ef31a21acdf1d8bfae07b6c5bb7 100644 (file)
--- a/target/linux/imx6/config-4.14
+++ b/target/linux/imx6/config-4.14
@@ -187,6 +187,8 @@ CONFIG_F2FS_FS=y
 # CONFIG_F2FS_FS_SECURITY is not set
 CONFIG_F2FS_FS_XATTR=y
 CONFIG_F2FS_STAT_FS=y
+CONFIG_EXTRA_FIRMWARE="imx/sdma/sdma-imx6q.bin"
+CONFIG_EXTRA_FIRMWARE_DIR="firmware"
 CONFIG_FEC=y
 CONFIG_FIXED_PHY=y
 CONFIG_FIX_EARLYCON_MEM=y