From 290ffe57886271a6ac6b7750f70410ee51727f42 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Mon, 25 Apr 2022 16:22:48 +0200 Subject: 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 Tested-by: Ying-Chun Liu (PaulLiu) Reviewed-by: Fabio Estevam --- drivers/ddr/imx/imx8m/ddrphy_utils.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'drivers/ddr/imx/imx8m/ddrphy_utils.c') diff --git a/drivers/ddr/imx/imx8m/ddrphy_utils.c b/drivers/ddr/imx/imx8m/ddrphy_utils.c index a54449e5f14..975d553674a 100644 --- 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; } -- cgit v1.2.3