At the moment the whole available memory is added to one single memory
bank "ram0". This can cause barebox chainload issues on devices with a
huge amount of memory like the i.MX8MP-EVK which has 6G of RAM if the
barebox pbl binary is to large.
The reason for this issues is that memory_bank_first_find_space()
returns the memory area with the largest amount of free space on the
first memory bank. So in case of Debix SOM-A 8G and i.MX8MP-EVK 6G this
is the area crossing the 4G boundary. This cause the barebox pbl code to
trigger a MMU exception once the early MMU gets enabled which is
configured for sizes <=4G.
Split the memory space into two memory banks: "ram0" and "ram1" to fix
this issue.
Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
---
Changelog:
v3:
- add comment
- add ifdef to fix 32bit compilation warning
v2:
- drop add_mem() usage and use arm_add_mem_device() directly
---
arch/arm/mach-imx/esdctl.c | 41 ++++++++++++++++++++++++++++++++++----
1 file changed, 37 insertions(+), 4 deletions(-)
diff --git a/arch/arm/mach-imx/esdctl.c b/arch/arm/mach-imx/esdctl.c
index 1798ad48e50a..2fca0a44a176 100644
--- a/arch/arm/mach-imx/esdctl.c
+++ b/arch/arm/mach-imx/esdctl.c
@@ -510,16 +510,49 @@ static resource_size_t imx8m_ddrc_sdram_size(void __iomem *ddrc, unsigned buswid
reduced_adress_space, mstr);
}
+static int _imx8m_ddrc_add_mem(void *mmdcbase, struct imx_esdctl_data *data,
+ unsigned int buswidth)
+{
+ resource_size_t size = imx8m_ddrc_sdram_size(mmdcbase, buswidth);
+ resource_size_t size0, size1;
+ int ret;
+
+ /*
+ * Split the available memory into multiple banks if the device does
+ * have more RAM than 3G. At the moment this is necessary to prevent
+ * memory_bank_first_find_space() from finding free space near the end
+ * of the 4G barrier which is the case in a 6G/8G setup. This is
+ * important for larger barebox-pbl binaries (e.g. debug enabled) and
+ * the barebox chainloading mechanism since the pbl init the MMU to 4G.
+ * In this case a MMU exception will be thrown if the barebox-pbl is
+ * placed near the 4G barrier.
+ */
+ size0 = min_t(resource_size_t, SZ_4G - MX8M_DDR_CSD1_BASE_ADDR, size);
+ size1 = size - size0;
+
+ ret = arm_add_mem_device("ram0", data->base0, size0);
+ if (ret || size1 == 0)
+ return ret;
+
+#ifdef CONFIG_64BIT
+ /*
+ * Albeit this hook is called on 64bit machines only, the driver serves
+ * 32bit machines as well. Guard the code to avoid compiler warnings.
+ */
+ ret = arm_add_mem_device("ram1", SZ_4G, size1);
+#endif
+
+ return ret;
+}
+
static int imx8m_ddrc_add_mem(void *mmdcbase, struct imx_esdctl_data *data)
{
- return arm_add_mem_device("ram0", data->base0,
- imx8m_ddrc_sdram_size(mmdcbase, 32));
+ return _imx8m_ddrc_add_mem(mmdcbase, data, 32);
}
static int imx8mn_ddrc_add_mem(void *mmdcbase, struct imx_esdctl_data *data)
{
- return arm_add_mem_device("ram0", data->base0,
- imx8m_ddrc_sdram_size(mmdcbase, 16));
+ return _imx8m_ddrc_add_mem(mmdcbase, data, 16);
}
static resource_size_t imx7d_ddrc_sdram_size(void __iomem *ddrc)
--
2.39.2
