imx8m: fix reading of DDR4 MR registers

I was trying to employ lpddr4_mr_read() to something similar to what
the imx8mm-cl-iot-gate board is doing for auto-detecting the RAM
type. However, the version in drivers/ddr/imx/imx8m/ddrphy_utils.c
differs from the private one used by that board in how it extracts the
byte value, and I was only getting zeroes. Adding a bit of debug
printf'ing gives me

 tmp = 0x00ffff00
 tmp = 0x00070700
 tmp = 0x00000000
 tmp = 0x00101000

and indeed I was expecting a (combined) value of 0xff070010 (0xff
being Manufacturer ID for Micron). I can't find any documentation that
says how the values are supposed to be read, but clearly the iot-gate
definition is the right one, both for its use case as well as my
imx8mp-based board.

So lift the private definition of lpddr4_mr_read() from the
imx8mm-cl-iot-gate board code to ddrphy_utils.c, and add a declaration
in the ddr.h header where e.g. get_trained_CDD() is already declared.

This has only been compile-tested for the imx8mm-cl-iot-gate
board (since I don't have the hardware), but since I've merely moved
its definition of lpddr4_mr_read(), I'd be surprised if it changed
anything for that board.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Tested-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Reviewed-by: Fabio Estevam <festevam@denx.de>

diff --git a/arch/arm/include/asm/arch-imx8m/ddr.h b/arch/arm/include/asm/arch-imx8m/ddr.h
index 0f1e832c038a00a9d6e5f002d5f33ba25db116b1..2ce8a8f2d41665e572d336d494f909f74de733a5 100644 (file)
--- a/arch/arm/include/asm/arch-imx8m/ddr.h
+++ b/arch/arm/include/asm/arch-imx8m/ddr.h
@@ -723,6 +723,7 @@ void ddrphy_init_read_msg_block(enum fw_type type);
 
 void update_umctl2_rank_space_setting(unsigned int pstat_num);
 void get_trained_CDD(unsigned int fsp);
+unsigned int lpddr4_mr_read(unsigned int mr_rank, unsigned int mr_addr);
 
 static inline void reg32_write(unsigned long addr, u32 val)
 {

diff --git a/board/compulab/imx8mm-cl-iot-gate/ddr/ddr.c b/board/compulab/imx8mm-cl-iot-gate/ddr/ddr.c
index 5b93491923e93bbc78fa9edc8ffa9a9959d6b372..b230478b611aa52be346014befcc04af96c4b7de 100644 (file)
--- a/board/compulab/imx8mm-cl-iot-gate/ddr/ddr.c
+++ b/board/compulab/imx8mm-cl-iot-gate/ddr/ddr.c
@@ -24,33 +24,6 @@
 
 #include <linux/delay.h>
 
-static unsigned int lpddr4_mr_read(unsigned int mr_rank, unsigned int mr_addr)
-{
-       unsigned int tmp;
-
-       reg32_write(DRC_PERF_MON_MRR0_DAT(0), 0x1);
-       do {
-               tmp = reg32_read(DDRC_MRSTAT(0));
-       } while (tmp & 0x1);
-
-       reg32_write(DDRC_MRCTRL0(0), (mr_rank << 4) | 0x1);
-       reg32_write(DDRC_MRCTRL1(0), (mr_addr << 8));
-       reg32setbit(DDRC_MRCTRL0(0), 31);
-       do {
-               tmp = reg32_read(DRC_PERF_MON_MRR0_DAT(0));
-       } while ((tmp & 0x8) == 0);
-       tmp = reg32_read(DRC_PERF_MON_MRR1_DAT(0));
-       reg32_write(DRC_PERF_MON_MRR0_DAT(0), 0x4);
-       while (tmp) { //try to find a significant byte in the word
-               if (tmp & 0xff) {
-                       tmp &= 0xff;
-                       break;
-               }
-               tmp >>= 8;
-       }
-       return tmp;
-}
-
 struct lpddr4_desc {
        char name[16];
        unsigned int id;

diff --git a/drivers/ddr/imx/imx8m/ddrphy_utils.c b/drivers/ddr/imx/imx8m/ddrphy_utils.c
index a54449e5f14b5de4bc524ebeb249ee61eafcccdb..975d553674a2a91443ee3df83fbb51e0e1e96015 100644 (file)
--- a/drivers/ddr/imx/imx8m/ddrphy_utils.c
+++ b/drivers/ddr/imx/imx8m/ddrphy_utils.c
@@ -198,9 +198,14 @@ unsigned int lpddr4_mr_read(unsigned int mr_rank, unsigned int mr_addr)
                tmp = reg32_read(DRC_PERF_MON_MRR0_DAT(0));
        } while ((tmp & 0x8) == 0);
        tmp = reg32_read(DRC_PERF_MON_MRR1_DAT(0));
-       tmp = tmp & 0xff;
        reg32_write(DRC_PERF_MON_MRR0_DAT(0), 0x4);
-
+       while (tmp) { //try to find a significant byte in the word
+               if (tmp & 0xff) {
+                       tmp &= 0xff;
+                       break;
+               }
+               tmp >>= 8;
+       }
        return tmp;
 }