* [PATCH] imx8m: fix reading of DDR4 MR registers [again]
@ 2022-10-06 12:56 Rasmus Villemoes
2022-10-06 13:17 ` Fabio Estevam
2022-10-24 13:54 ` sbabic
0 siblings, 2 replies; 3+ messages in thread
From: Rasmus Villemoes @ 2022-10-06 12:56 UTC (permalink / raw)
To: u-boot
Cc: Ye Li, Peng Fan, Ying-Chun Liu, Fabio Estevam, Marek Vasut,
Rasmus Villemoes
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 <rasmus.villemoes@prevas.dk>
---
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 d964184ddc..52a4aa6323 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;
}
--
2.37.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] imx8m: fix reading of DDR4 MR registers [again]
2022-10-06 12:56 [PATCH] imx8m: fix reading of DDR4 MR registers [again] Rasmus Villemoes
@ 2022-10-06 13:17 ` Fabio Estevam
2022-10-24 13:54 ` sbabic
1 sibling, 0 replies; 3+ messages in thread
From: Fabio Estevam @ 2022-10-06 13:17 UTC (permalink / raw)
To: Rasmus Villemoes; +Cc: u-boot, Ye Li, Peng Fan, Ying-Chun Liu, Marek Vasut
Hi Rasmus,
On 06/10/2022 09:56, Rasmus Villemoes wrote:
> 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 <rasmus.villemoes@prevas.dk>
Thanks for the fix:
Reviewed-by: Fabio Estevam <festevam@denx.de>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] imx8m: fix reading of DDR4 MR registers [again]
2022-10-06 12:56 [PATCH] imx8m: fix reading of DDR4 MR registers [again] Rasmus Villemoes
2022-10-06 13:17 ` Fabio Estevam
@ 2022-10-24 13:54 ` sbabic
1 sibling, 0 replies; 3+ messages in thread
From: sbabic @ 2022-10-24 13:54 UTC (permalink / raw)
To: Rasmus Villemoes, u-boot
> 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 <rasmus.villemoes@prevas.dk>
> Reviewed-by: Fabio Estevam <festevam@denx.de>
Applied to u-boot-imx, master, thanks !
Best regards,
Stefano Babic
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2022-10-06 13:17 ` Fabio Estevam
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