Add a Kconfig option which users can select when they want to boot older
kernels, e.g. the linux-sunxi 3.4 kernels. For now this just forces the pll5
"p" value to 1 (divide by 2) as that is what those kernels are hardcoded too,
in the future this may enable further workarounds.
Signed-off-by: Hans de Goede <hdego...@redhat.com>
--
Changes in v2:
-s/CONFIG_OLD_KERNEL_COMPAT/CONFIG_OLD_SUNXI_KERNEL_COMPAT.
-Move the code block setting P(1) for old kernels to where P gets cleared
---
arch/arm/cpu/armv7/sunxi/dram.c | 4 ++++
board/sunxi/Kconfig | 7 +++++++
2 files changed, 11 insertions(+)
diff --git a/arch/arm/cpu/armv7/sunxi/dram.c b/arch/arm/cpu/armv7/sunxi/dram.c
index 0cbcf57..3cf3cbf 100644
--- a/arch/arm/cpu/armv7/sunxi/dram.c
+++ b/arch/arm/cpu/armv7/sunxi/dram.c
@@ -262,6 +262,10 @@ static void mctl_setup_dram_clock(u32 clk, u32 mbus_clk)
reg_val &= ~CCM_PLL5_CTRL_K_MASK; /* set K to 0 (x1) */
reg_val &= ~CCM_PLL5_CTRL_N_MASK; /* set N to 0 (x0) */
reg_val &= ~CCM_PLL5_CTRL_P_MASK; /* set P to 0 (x1) */
+#ifdef CONFIG_OLD_SUNXI_KERNEL_COMPAT
+ /* Old kernels are hardcoded to P=1 (divide by 2) */
+ reg_val |= CCM_PLL5_CTRL_P(1);
+#endif
if (clk >= 540 && clk < 552) {
/* dram = 540MHz */
reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(2));
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 121d7d0..fb650c0 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -20,6 +20,13 @@ config SYS_SOC
config FDTFILE
string "Default fdtfile env setting for this board"
+config OLD_SUNXI_KERNEL_COMPAT
+ boolean "Enable workarounds for booting old kernels"
+ default n
+ ---help---
+ Set this to enable various workarounds for old kernels, this results in
+ sub-optimal settings for newer kernels, only enable if needed.
+
config MMC0_CD_PIN
string "Card detect pin for mmc0"
default ""
--
2.1.0
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