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ARM: at91: pm: fix self-refresh for sama7g5

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It has been discovered that on some parts, from time to time, self-refresh
procedure doesn't work as expected. Debugging and investigating it proved
that disabling AC DLL introduce glitches in RAM controllers which
leads to unexpected behavior. This is confirmed as a hardware bug. DLL
bypass disables 3 DLLs: 2 DX DLLs and AC DLL. Thus, keep only DX DLLs
disabled. This introduce 6mA extra current consumption on VDDCORE when
switching to any ULP mode or standby mode but the self-refresh procedure
still works.

Fixes: f0bbf17958 ("ARM: at91: pm: add self-refresh support for sama7g5")
Suggested-by: Frederic Schumacher <frederic.schumacher@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Tested-by: Cristian Birsan <cristian.birsan@microchip.com>
Link: https://lore.kernel.org/r/20220826083927.3107272-3-claudiu.beznea@microchip.com
This commit is contained in:
Claudiu Beznea 2022-08-26 11:39:20 +03:00
parent f04445fa09
commit a02875c4cb
2 changed files with 21 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
arch/arm/mach-at91/pm_suspend.S
View File

@ -172,9 +172,15 @@ sr_ena_2:
/* Put DDR PHY's DLL in bypass mode for non-backup modes. */
cmp r7, #AT91_PM_BACKUP
beq sr_ena_3
ldr tmp1, [r3, #DDR3PHY_PIR]
orr tmp1, tmp1, #DDR3PHY_PIR_DLLBYP
str tmp1, [r3, #DDR3PHY_PIR]
/* Disable DX DLLs. */
ldr tmp1, [r3, #DDR3PHY_DX0DLLCR]
orr tmp1, tmp1, #DDR3PHY_DXDLLCR_DLLDIS
str tmp1, [r3, #DDR3PHY_DX0DLLCR]
ldr tmp1, [r3, #DDR3PHY_DX1DLLCR]
orr tmp1, tmp1, #DDR3PHY_DXDLLCR_DLLDIS
str tmp1, [r3, #DDR3PHY_DX1DLLCR]
sr_ena_3:
/* Power down DDR PHY data receivers. */
@ -221,10 +227,14 @@ sr_ena_3:
bic tmp1, tmp1, #DDR3PHY_DSGCR_ODTPDD_ODT0
str tmp1, [r3, #DDR3PHY_DSGCR]
/* Take DDR PHY's DLL out of bypass mode. */
ldr tmp1, [r3, #DDR3PHY_PIR]
bic tmp1, tmp1, #DDR3PHY_PIR_DLLBYP
str tmp1, [r3, #DDR3PHY_PIR]
/* Enable DX DLLs. */
ldr tmp1, [r3, #DDR3PHY_DX0DLLCR]
bic tmp1, tmp1, #DDR3PHY_DXDLLCR_DLLDIS
str tmp1, [r3, #DDR3PHY_DX0DLLCR]
ldr tmp1, [r3, #DDR3PHY_DX1DLLCR]
bic tmp1, tmp1, #DDR3PHY_DXDLLCR_DLLDIS
str tmp1, [r3, #DDR3PHY_DX1DLLCR]
/* Enable quasi-dynamic programming. */
mov tmp1, #0

4
include/soc/at91/sama7-ddr.h
View File

@ -39,6 +39,10 @@
#define DDR3PHY_ZQ0SR0 (0x188) /* ZQ status register 0 */
#define DDR3PHY_DX0DLLCR (0x1CC) /* DDR3PHY DATX8 DLL Control Register */
#define DDR3PHY_DX1DLLCR (0x20C) /* DDR3PHY DATX8 DLL Control Register */
#define DDR3PHY_DXDLLCR_DLLDIS (1 << 31) /* DLL Disable */
/* UDDRC */
#define UDDRC_STAT (0x04) /* UDDRC Operating Mode Status Register */
#define UDDRC_STAT_SELFREF_TYPE_DIS (0x0 << 4) /* SDRAM is not in Self-refresh */