From: Li Bin bin.li@microchip.com
[ Upstream commit bc4722c3598d0e2c2dbf9609a3d3198993093e2b ]
For sama7g5 and sama7d65 backup mode, we encountered a "ZQ calibrate error" during recalibrating the impedance in BootStrap. We found that the impedance value saved in at91_suspend_finish() before the DDR entered self-refresh mode did not match the resistor values. The ZDATA field in the DDR3PHY_ZQ0CR0 register uses a modified gray code to select the different impedance setting. But these gray code are incorrect, a workaournd from design team fixed the bug in the calibration logic. The ZDATA contains four independent impedance elements, but the algorithm combined the four elements into one. The elements were fixed using properly shifted offsets.
Signed-off-by: Li Bin bin.li@microchip.com [nicolas.ferre@microchip.com: fix indentation and combine 2 patches] Signed-off-by: Nicolas Ferre nicolas.ferre@microchip.com Tested-by: Ryan Wanner Ryan.Wanner@microchip.com Tested-by: Durai Manickam KR durai.manickamkr@microchip.com Tested-by: Andrei Simion andrei.simion@microchip.com Signed-off-by: Ryan Wanner Ryan.Wanner@microchip.com Link: https://lore.kernel.org/r/28b33f9bcd0ca60ceba032969fe054d38f2b9577.174067115... Signed-off-by: Claudiu Beznea claudiu.beznea@tuxon.dev Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mach-at91/pm.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c index 4d0d0d49a7442..77aec670f635c 100644 --- a/arch/arm/mach-at91/pm.c +++ b/arch/arm/mach-at91/pm.c @@ -537,11 +537,12 @@ extern u32 at91_pm_suspend_in_sram_sz;
static int at91_suspend_finish(unsigned long val) { - unsigned char modified_gray_code[] = { - 0x00, 0x01, 0x02, 0x03, 0x06, 0x07, 0x04, 0x05, 0x0c, 0x0d, - 0x0e, 0x0f, 0x0a, 0x0b, 0x08, 0x09, 0x18, 0x19, 0x1a, 0x1b, - 0x1e, 0x1f, 0x1c, 0x1d, 0x14, 0x15, 0x16, 0x17, 0x12, 0x13, - 0x10, 0x11, + /* SYNOPSYS workaround to fix a bug in the calibration logic */ + unsigned char modified_fix_code[] = { + 0x00, 0x01, 0x01, 0x06, 0x07, 0x0c, 0x06, 0x07, 0x0b, 0x18, + 0x0a, 0x0b, 0x0c, 0x0d, 0x0d, 0x0a, 0x13, 0x13, 0x12, 0x13, + 0x14, 0x15, 0x15, 0x12, 0x18, 0x19, 0x19, 0x1e, 0x1f, 0x14, + 0x1e, 0x1f, }; unsigned int tmp, index; int i; @@ -552,25 +553,25 @@ static int at91_suspend_finish(unsigned long val) * restore the ZQ0SR0 with the value saved here. But the * calibration is buggy and restoring some values from ZQ0SR0 * is forbidden and risky thus we need to provide processed - * values for these (modified gray code values). + * values for these. */ tmp = readl(soc_pm.data.ramc_phy + DDR3PHY_ZQ0SR0);
/* Store pull-down output impedance select. */ index = (tmp >> DDR3PHY_ZQ0SR0_PDO_OFF) & 0x1f; - soc_pm.bu->ddr_phy_calibration[0] = modified_gray_code[index]; + soc_pm.bu->ddr_phy_calibration[0] = modified_fix_code[index] << DDR3PHY_ZQ0SR0_PDO_OFF;
/* Store pull-up output impedance select. */ index = (tmp >> DDR3PHY_ZQ0SR0_PUO_OFF) & 0x1f; - soc_pm.bu->ddr_phy_calibration[0] |= modified_gray_code[index]; + soc_pm.bu->ddr_phy_calibration[0] |= modified_fix_code[index] << DDR3PHY_ZQ0SR0_PUO_OFF;
/* Store pull-down on-die termination impedance select. */ index = (tmp >> DDR3PHY_ZQ0SR0_PDODT_OFF) & 0x1f; - soc_pm.bu->ddr_phy_calibration[0] |= modified_gray_code[index]; + soc_pm.bu->ddr_phy_calibration[0] |= modified_fix_code[index] << DDR3PHY_ZQ0SR0_PDODT_OFF;
/* Store pull-up on-die termination impedance select. */ index = (tmp >> DDR3PHY_ZQ0SRO_PUODT_OFF) & 0x1f; - soc_pm.bu->ddr_phy_calibration[0] |= modified_gray_code[index]; + soc_pm.bu->ddr_phy_calibration[0] |= modified_fix_code[index] << DDR3PHY_ZQ0SRO_PUODT_OFF;
/* * The 1st 8 words of memory might get corrupted in the process