Hi James,
Le jeu. 11 janv. 2018 à 0:20, James Hogan <james.hogan@xxxxxxxx> a
écrit :
On Fri, Jan 05, 2018 at 07:25:11PM +0100, Paul Cercueil wrote:
[...]
+
+/*
+ * We have seen MMC DMA transfers read corrupted data from SDRAM
when a burst
+ * interval ends at physical address 0x10000000. To avoid this
problem, we
+ * remove the final page of low memory from the memory map.
+ */
+void __init jz4770_reserve_unsafe_for_dma(void)
+{
+ int i;
+
+ for (i = 0; i < boot_mem_map.nr_map; i++) {
+ struct boot_mem_map_entry *entry = boot_mem_map.map + i;
+
+ if (entry->type != BOOT_MEM_RAM)
+ continue;
+
+ if (entry->addr + entry->size != 0x10000000)
+ continue;
+
+ entry->size -= PAGE_SIZE;
+ break;
+ }
+}
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 85bc601e9a0d..5a2c20145aee 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -879,6 +879,14 @@ static void __init arch_mem_init(char
**cmdline_p)
parse_early_param();
+#ifdef CONFIG_MACH_JZ4770
+ if (current_cpu_type() == CPU_JZRISC &&
+ mips_machtype == MACH_INGENIC_JZ4770) {
+ extern void __init jz4770_reserve_unsafe_for_dma(void);
+ jz4770_reserve_unsafe_for_dma();
+ }
+#endif
Hmm, a little bit ugly. I'm guessing the plat_mem_setup() callback is
too early since mem= parameters won't have been taken into account yet
from parse_early_param().
Is /memreserve/ in FDT of any value here or is it all too late due to
old DTs?
Cheers
James
When trying to test whether or not /memreserve/ fixes the corruption
bug we were
having, we ran into the problem that we can't reproduce it anymore.
Sigh.
So I'll skip this patch in the next patchset version, and handle this
later if
it reappears.
-Paul
