[PATCH v1 1/2] arm64: dts: rockchip: Disable HS400 for eMMC on ROCK Pi 4

[Christopher Obbard]

There is some instablity with some eMMC modules on ROCK Pi 4 SBCs running
in HS400 mode. This ends up resulting in some block errors after a while
or after a "heavy" operation utilising the eMMC (e.g. resizing a
filesystem). An example of these errors is as follows:

    [  289.171014] mmc1: running CQE recovery
    [  290.048972] mmc1: running CQE recovery
    [  290.054834] mmc1: running CQE recovery
    [  290.060817] mmc1: running CQE recovery
    [  290.061337] blk_update_request: I/O error, dev mmcblk1, sector 1411072 op 0x1:(WRITE) flags 0x800 phys_seg 36 prio class 0
    [  290.061370] EXT4-fs warning (device mmcblk1p1): ext4_end_bio:348: I/O error 10 writing to inode 29547 starting block 176466)
    [  290.061484] Buffer I/O error on device mmcblk1p1, logical block 172288
    [  290.061531] Buffer I/O error on device mmcblk1p1, logical block 172289
    [  290.061551] Buffer I/O error on device mmcblk1p1, logical block 172290
    [  290.061574] Buffer I/O error on device mmcblk1p1, logical block 172291
    [  290.061592] Buffer I/O error on device mmcblk1p1, logical block 172292
    [  290.061615] Buffer I/O error on device mmcblk1p1, logical block 172293
    [  290.061632] Buffer I/O error on device mmcblk1p1, logical block 172294
    [  290.061654] Buffer I/O error on device mmcblk1p1, logical block 172295
    [  290.061673] Buffer I/O error on device mmcblk1p1, logical block 172296
    [  290.061695] Buffer I/O error on device mmcblk1p1, logical block 172297

Disabling the Command Queue seems to stop the CQE recovery from running,
but doesn't seem to improve the I/O errors. Until this can be investigated
further, disable HS400 mode on the ROCK Pi 4 SBCs to at least stop I/O
errors from occurring.

While we are here, set the eMMC maximum clock frequency to 1.5MHz to
follow the ROCK 4C+.

Fixes: 1b5715c602fd ("arm64: dts: rockchip: add ROCK Pi 4 DTS support")
Signed-off-by: Christopher Obbard <chris.obbard@xxxxxxxxxxxxx>
---

 arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
index 907071d4fe80..95efee311ece 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
@@ -645,9 +645,9 @@ &saradc {
 };
 
 &sdhci {
+	max-frequency = <150000000>;
 	bus-width = <8>;
-	mmc-hs400-1_8v;
-	mmc-hs400-enhanced-strobe;
+	mmc-hs200-1_8v;
 	non-removable;
 	status = "okay";
 };
-- 
2.40.1