From c9473b2c37059e3c84d07fb663316c17c5480b53 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Thu, 6 Oct 2022 14:56:50 +0200 Subject: [PATCH] imx8m: fix reading of DDR4 MR registers [again] Commit 290ffe5788 (imx8m: fix reading of DDR4 MR registers) lifted a private definition of lpddr4_mr_read() from imx8mm-cl-iot-gate board code to drivers/ddr/imx/imx8m/ddrphy_utils.c, because that version actually seems to work in practice. However, commit 99c7cc58e1 (ddr: imx: Add i.MX9 DDR controller driver) reintroduced the broken version in drivers/ddr/imx/imx8m/ddr_init.c, copied most of the rest of ddrphy_utils.c to drivers/ddr/imx/phy/ddrphy_utils.c, and stopped building drivers/ddr/imx/imx8m/ddrphy_utils.c [and that file was then finally completely removed with 7e9bd84883 (imx8m: ddrphy_utils: Remove unused file)]. I assume this must have broken the imx8mm-cl-iot-gate board, at least those that have not had their eeprom programmed with the proper information. It certainly did break our out-of-tree board which always reads back the ID register and uses that for a sanity check. So apply the fix from 290ffe5788 once again. Fixes: 99c7cc58e1 (ddr: imx: Add i.MX9 DDR controller driver) Signed-off-by: Rasmus Villemoes Reviewed-by: Fabio Estevam --- drivers/ddr/imx/imx8m/ddr_init.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/ddr/imx/imx8m/ddr_init.c b/drivers/ddr/imx/imx8m/ddr_init.c index d964184..52a4aa6 100644 --- a/drivers/ddr/imx/imx8m/ddr_init.c +++ b/drivers/ddr/imx/imx8m/ddr_init.c @@ -134,8 +134,14 @@ 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; } -- 2.7.4