arm: timer: sunxi: add Allwinner timer erratum workaround
The Allwinner A64 SoCs suffers from an arch timer implementation erratum,
where sometimes the lower 11 bits of the counter value erroneously
become all 0's or all 1's [1]. This leads to sudden jumps, both forwards and
backwards, with the latter one often showing weird behaviour.
Port the workaround proposed for Linux to U-Boot and activate it for all
A64 boards.
This fixes crashes when accessing MMC devices (SD cards), caused by a
recent change to actually use the counter value for timeout checks.
Fixes: 5ff8e54888e4d26a352453564f7f599d29696dc9 ("sunxi: improve throughput
in the sunxi_mmc driver")
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/576886.html
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Andreas Färber <afaerber@suse.de>
Tested-by: Guillaume Gardet <guillaume.gardet@free.fr>
diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
index a3f7723..3624a03 100644
--- a/arch/arm/mach-sunxi/Kconfig
+++ b/arch/arm/mach-sunxi/Kconfig
@@ -84,6 +84,9 @@
Chips using the latter setup are supposed to select this option to
adjust the addresses accordingly.
+config SUNXI_A64_TIMER_ERRATUM
+ bool
+
# Note only one of these may be selected at a time! But hidden choices are
# not supported by Kconfig
config SUNXI_GEN_SUN4I
@@ -270,6 +273,7 @@
select SUNXI_DRAM_DW_32BIT
select FIT
select SPL_LOAD_FIT
+ select SUNXI_A64_TIMER_ERRATUM
config MACH_SUN50I_H5
bool "sun50i (Allwinner H5)"