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imx8m: fix reading of DDR4 MR registers

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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>
This commit is contained in:
Rasmus Villemoes 2022-04-25 16:22:48 +02:00 • committed by Stefano Babic
parent c329f9349b
commit 290ffe5788
3 changed files with 8 additions and 29 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
arch/arm/include/asm/arch-imx8m/ddr.h
View file

@ -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)
{

27
board/compulab/imx8mm-cl-iot-gate/ddr/ddr.c
View file

@ -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;

9
drivers/ddr/imx/imx8m/ddrphy_utils.c
View file

@ -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;
}