diff mbox series

ARM: dts: at91: sama7g5ek: Align the impedance of the QSPI0's HSIO and PCB lines

Message ID 20220408091036.749648-1-tudor.ambarus@microchip.com
State Accepted
Commit 1b0eec3c9f04f9cb9d5e5ceac21da140e69a13f8
Delegated to: Eugen Hristev
Headers show
Series ARM: dts: at91: sama7g5ek: Align the impedance of the QSPI0's HSIO and PCB lines | expand

Commit Message

Tudor Ambarus April 8, 2022, 9:10 a.m. UTC
The impedance of the QSPI PCB lines on the sama7g5ek is 50 Ohms.
Align the output impedance of the QSPI0 HSIOs by setting a medium drive
strength which corresponds to an impedance of 56 Ohms when VDD is in the
3.0V - 3.6V range. The high drive strength setting corresponds to an
output impedance of 42 Ohms on the QSPI0 HSIOs.
This is just a fine tunning. The memory that we have populated on sama7g5ek
works fine even with high drive strength, but it's better to adjust it and
use medium instead, in case some other flashes with higher frequencies are
tested.

Suggested-by: Mihai Sain <mihai.sain@microchip.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 arch/arm/dts/at91-sama7g5ek.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Eugen Hristev April 27, 2022, 6:08 a.m. UTC | #1
On 4/8/22 12:10 PM, Tudor Ambarus wrote:
> The impedance of the QSPI PCB lines on the sama7g5ek is 50 Ohms.
> Align the output impedance of the QSPI0 HSIOs by setting a medium drive
> strength which corresponds to an impedance of 56 Ohms when VDD is in the
> 3.0V - 3.6V range. The high drive strength setting corresponds to an
> output impedance of 42 Ohms on the QSPI0 HSIOs.
> This is just a fine tunning. The memory that we have populated on sama7g5ek
> works fine even with high drive strength, but it's better to adjust it and
> use medium instead, in case some other flashes with higher frequencies are
> tested.
> 
> Suggested-by: Mihai Sain <mihai.sain@microchip.com>
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> ---

Applied to u-boot-at91/master, thanks !
diff mbox series

Patch

diff --git a/arch/arm/dts/at91-sama7g5ek.dts b/arch/arm/dts/at91-sama7g5ek.dts
index 5313c6d160..ee46112b08 100644
--- a/arch/arm/dts/at91-sama7g5ek.dts
+++ b/arch/arm/dts/at91-sama7g5ek.dts
@@ -667,7 +667,7 @@ 
 			 <PIN_PB21__QSPI0_INT>;
 		bias-disable;
 		slew-rate = <0>;
-		atmel,drive-strength = <ATMEL_PIO_DRVSTR_HI>;
+		atmel,drive-strength = <ATMEL_PIO_DRVSTR_ME>;
 	};
 
 	pinctrl_sdmmc0_default: sdmmc0_default {