fix(imx8m): fix the dram retention random hang on some imx8mq Rev2.0

It seems the DRAM APB clock root slice can NOT work normally
if the PLLs is power down in DSM mode. So update this clock
slice's setting explicitly to make it work. This piece of code
is there for a long while on previous release, so just add
it back to align with previous flow.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Reviewed-by: Anson Huang <Anson.Huang@nxp.com>
Change-Id: I113069494074194e116fdb1229052d2956bf90ea

diff --git a/plat/imx/imx8m/ddr/dram_retention.c b/plat/imx/imx8m/ddr/dram_retention.c
index 96591d18ba8bd5828f4f8b9e94625c1c86dc6613..adcae57b93dc18fe84741e370a2f0125eef50004 100644 (file)
--- a/plat/imx/imx8m/ddr/dram_retention.c
+++ b/plat/imx/imx8m/ddr/dram_retention.c
@@ -18,8 +18,10 @@
 #define GPC_PU_PWRHSK          (IMX_GPC_BASE + 0x01FC)
 #define CCM_SRC_CTRL_OFFSET     (IMX_CCM_BASE + 0x800)
 #define CCM_CCGR_OFFSET         (IMX_CCM_BASE + 0x4000)
+#define CCM_TARGET_ROOT_OFFSET (IMX_CCM_BASE + 0x8000)
 #define CCM_SRC_CTRL(n)                (CCM_SRC_CTRL_OFFSET + 0x10 * (n))
 #define CCM_CCGR(n)            (CCM_CCGR_OFFSET + 0x10 * (n))
+#define CCM_TARGET_ROOT(n)     (CCM_TARGET_ROOT_OFFSET + 0x80 * (n))
 
 #define DRAM_PLL_CTRL          (IMX_ANAMIX_BASE + 0x50)
 
@@ -142,6 +144,10 @@ void dram_exit_retention(void)
        mmio_write_32(CCM_CCGR(5), 2);
        mmio_write_32(CCM_SRC_CTRL(15), 2);
 
+       /* change the clock source of dram_apb_clk_root */
+       mmio_write_32(CCM_TARGET_ROOT(65) + 0x8, (0x7 << 24) | (0x7 << 16));
+       mmio_write_32(CCM_TARGET_ROOT(65) + 0x4, (0x4 << 24) | (0x3 << 16));
+
        /* disable iso */
        mmio_setbits_32(IMX_GPC_BASE + PU_PGC_UP_TRG, BIT(5));
        mmio_write_32(SRC_DDR1_RCR, 0x8F000006);