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Subject[PATCH] ARM: zynq: Reserve not DMAable space in front of the kernel
Date
Reserve space from 0x0 - __pa(swapper_pg_dir),
if kernel is loaded from 0, which is not DMAable.
It is causing problem with MMC driver and others
which want to add dma buffers to this space.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

Jason: I don't think it is worth to bring 0x8000 magic
value and count minimum from it and phys_addr of swapper_pg_dir.
Full 512k of memory shouldn't be used by DMA.

---
arch/arm/mach-zynq/common.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c
index 1db2a5ca..8c09a83 100644
--- a/arch/arm/mach-zynq/common.c
+++ b/arch/arm/mach-zynq/common.c
@@ -25,6 +25,7 @@
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/of.h>
+#include <linux/memblock.h>
#include <linux/irqchip.h>
#include <linux/irqchip/arm-gic.h>

@@ -41,6 +42,18 @@

void __iomem *zynq_scu_base;

+/**
+ * zynq_memory_init - Initialize special memory
+ *
+ * We need to stop things allocating the low memory as DMA can't work in
+ * the 1st 512K of memory.
+ */
+static void __init zynq_memory_init(void)
+{
+ if (!__pa(PAGE_OFFSET))
+ memblock_reserve(__pa(PAGE_OFFSET), __pa(swapper_pg_dir));
+}
+
static struct platform_device zynq_cpuidle_device = {
.name = "cpuidle-zynq",
};
@@ -117,5 +130,6 @@ DT_MACHINE_START(XILINX_EP107, "Xilinx Zynq Platform")
.init_machine = zynq_init_machine,
.init_time = zynq_timer_init,
.dt_compat = zynq_dt_match,
+ .reserve = zynq_memory_init,
.restart = zynq_system_reset,
MACHINE_END
--
1.8.2.3
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