From: Claudiu Beznea claudiu.beznea@microchip.com
[ Upstream commit a02875c4cbd6f3d2f33d70cc158a19ef02d4b84f ]
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: f0bbf17958e8 ("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.... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mach-at91/pm_suspend.S | 24 +++++++++++++++++------- include/soc/at91/sama7-ddr.h | 4 ++++ 2 files changed, 21 insertions(+), 7 deletions(-)
diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S index fdb4f63ecde4b..65cfcc19a936c 100644 --- a/arch/arm/mach-at91/pm_suspend.S +++ b/arch/arm/mach-at91/pm_suspend.S @@ -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 diff --git a/include/soc/at91/sama7-ddr.h b/include/soc/at91/sama7-ddr.h index f6542584ca139..f47a933df82ea 100644 --- a/include/soc/at91/sama7-ddr.h +++ b/include/soc/at91/sama7-ddr.h @@ -41,6 +41,10 @@
#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 */