[U-Boot] [PATCH v3 1/2] spl: rk3399: disable DDR security regions for SPL (for DMA in dw_mmc)

[Philipp Tomsich]

The RK3399 hangs during DMA of the Designware MMC controller, when
performing DMA-based transactions in SPL due to the DDR security settings
left behind by the BootROM (i.e. accesses to the first MB of DRAM are
restricted... however, the DMA is likely to target this first MB, as it
transfers from/to the stack).

System security is not affected, as the final security configuration is
performed by the ATF, which is executed after the SPL stage.

With this fix in place, we can now drop 'fifo-mode' in the DTS for the
RK3399-Q7 (Puma).

Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>

---

Changes in v3:
- replaces the work-around (i.e. falling back to fifo-mode in SPL) with
  a permanent fix

 arch/arm/mach-rockchip/rk3399-board-spl.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/mach-rockchip/rk3399-board-spl.c b/arch/arm/mach-rockchip/rk3399-board-spl.c
index 3bfc2d9..c5e32c4 100644
--- a/arch/arm/mach-rockchip/rk3399-board-spl.c
+++ b/arch/arm/mach-rockchip/rk3399-board-spl.c
@@ -186,6 +186,7 @@ void board_debug_uart_init(void)
 }
 
 #define GRF_EMMCCORE_CON11 0xff77f02c
+#define SGRF_DDR_RGN_CON16 0xff330040
 void board_init_f(ulong dummy)
 {
 	struct udevice *pinctrl;
@@ -214,6 +215,17 @@ void board_init_f(ulong dummy)
 		hang();
 	}
 
+	/*
+	 * Disable DDR security regions.
+	 *
+	 * As we are entered from the BootROM, the region from
+	 * 0x0 through 0xfffff (i.e. the first MB of memory) will
+	 * be protected. This will cause issues with the DW_MMC
+	 * driver, which tries to DMA from/to the stack (likely)
+	 * located in this range.
+	 */
+	rk_clrsetreg(SGRF_DDR_RGN_CON16, 0x1FF, 0);
+
 	secure_timer_init();
 
 	ret = uclass_get_device(UCLASS_PINCTRL, 0, &pinctrl);
@@ -251,6 +263,7 @@ void spl_board_init(void)
 #ifdef CONFIG_ROCKCHIP_SPL_BACK_TO_BROM
 	back_to_bootrom();
 #endif
+
 	return;
 err:
 	printf("spl_board_init: Error %d\n", ret);
-- 
1.9.1