* [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218
@ 2016-06-15 6:13 ` Keerthy
0 siblings, 0 replies; 6+ messages in thread
From: Keerthy @ 2016-06-15 6:13 UTC (permalink / raw)
To: tony
Cc: robh+dt, j-keerthy, mark.rutland, d-gerlach, nm, linux-omap,
devicetree, linux-arm-kernel, linux-kernel, Franklin S Cooper Jr,
Aparna Balasubramanian
From: Dave Gerlach <d-gerlach@ti.com>
Based on the latest timing specifications for the TPS65218 from the data
sheet, http://www.ti.com/lit/ds/symlink/tps65218.pdf, document SLDS206
from November 2014, we must change the i2c bus speed to better fit within
the minimum high SCL time required for proper i2c transfer.
When running at 400khz, measurements show that SCL spends
0.8125 uS/1.666 uS high/low which violates the requirement for minimum
high period of SCL provided in datasheet Table 7.6 which is 1 uS.
Switching to 100khz gives us 5 uS/5 uS high/low which both fall above
the minimum given values for 100 khz, 4.0 uS/4.7 uS high/low.
Without this patch occasionally a voltage set operation from the kernel
will appear to have worked but the actual voltage reflected on the PMIC
will not have updated, causing problems especially with cpufreq that may
update to a higher OPP without actually raising the voltage on DCDC2,
leading to a hang.
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Aparna Balasubramanian <aparnab@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
---
arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
index 18a3445..5f67001 100644
--- a/arch/arm/boot/dts/am437x-sk-evm.dts
+++ b/arch/arm/boot/dts/am437x-sk-evm.dts
@@ -490,7 +490,7 @@
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&i2c0_pins>;
- clock-frequency = <400000>;
+ clock-frequency = <100000>;
tps@24 {
compatible = "ti,tps65218";
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218
@ 2016-06-15 6:13 ` Keerthy
0 siblings, 0 replies; 6+ messages in thread
From: Keerthy @ 2016-06-15 6:13 UTC (permalink / raw)
To: tony-4v6yS6AI5VpBDgjK7y7TUQ
Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A, j-keerthy-l0cyMroinI0,
mark.rutland-5wv7dgnIgG8, d-gerlach-l0cyMroinI0, nm-l0cyMroinI0,
linux-omap-u79uwXL29TY76Z2rM5mHXA,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Franklin S Cooper Jr,
Aparna Balasubramanian
From: Dave Gerlach <d-gerlach-l0cyMroinI0@public.gmane.org>
Based on the latest timing specifications for the TPS65218 from the data
sheet, http://www.ti.com/lit/ds/symlink/tps65218.pdf, document SLDS206
from November 2014, we must change the i2c bus speed to better fit within
the minimum high SCL time required for proper i2c transfer.
When running at 400khz, measurements show that SCL spends
0.8125 uS/1.666 uS high/low which violates the requirement for minimum
high period of SCL provided in datasheet Table 7.6 which is 1 uS.
Switching to 100khz gives us 5 uS/5 uS high/low which both fall above
the minimum given values for 100 khz, 4.0 uS/4.7 uS high/low.
Without this patch occasionally a voltage set operation from the kernel
will appear to have worked but the actual voltage reflected on the PMIC
will not have updated, causing problems especially with cpufreq that may
update to a higher OPP without actually raising the voltage on DCDC2,
leading to a hang.
Signed-off-by: Dave Gerlach <d-gerlach-l0cyMroinI0@public.gmane.org>
Signed-off-by: Nishanth Menon <nm-l0cyMroinI0@public.gmane.org>
Signed-off-by: Franklin S Cooper Jr <fcooper-l0cyMroinI0@public.gmane.org>
Signed-off-by: Aparna Balasubramanian <aparnab-l0cyMroinI0@public.gmane.org>
Signed-off-by: Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org>
---
arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
index 18a3445..5f67001 100644
--- a/arch/arm/boot/dts/am437x-sk-evm.dts
+++ b/arch/arm/boot/dts/am437x-sk-evm.dts
@@ -490,7 +490,7 @@
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&i2c0_pins>;
- clock-frequency = <400000>;
+ clock-frequency = <100000>;
tps@24 {
compatible = "ti,tps65218";
--
1.9.1
--
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218
@ 2016-06-15 6:13 ` Keerthy
0 siblings, 0 replies; 6+ messages in thread
From: Keerthy @ 2016-06-15 6:13 UTC (permalink / raw)
To: linux-arm-kernel
From: Dave Gerlach <d-gerlach@ti.com>
Based on the latest timing specifications for the TPS65218 from the data
sheet, http://www.ti.com/lit/ds/symlink/tps65218.pdf, document SLDS206
from November 2014, we must change the i2c bus speed to better fit within
the minimum high SCL time required for proper i2c transfer.
When running at 400khz, measurements show that SCL spends
0.8125 uS/1.666 uS high/low which violates the requirement for minimum
high period of SCL provided in datasheet Table 7.6 which is 1 uS.
Switching to 100khz gives us 5 uS/5 uS high/low which both fall above
the minimum given values for 100 khz, 4.0 uS/4.7 uS high/low.
Without this patch occasionally a voltage set operation from the kernel
will appear to have worked but the actual voltage reflected on the PMIC
will not have updated, causing problems especially with cpufreq that may
update to a higher OPP without actually raising the voltage on DCDC2,
leading to a hang.
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Aparna Balasubramanian <aparnab@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
---
arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
index 18a3445..5f67001 100644
--- a/arch/arm/boot/dts/am437x-sk-evm.dts
+++ b/arch/arm/boot/dts/am437x-sk-evm.dts
@@ -490,7 +490,7 @@
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&i2c0_pins>;
- clock-frequency = <400000>;
+ clock-frequency = <100000>;
tps at 24 {
compatible = "ti,tps65218";
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218
2016-06-15 6:13 ` Keerthy
(?)
@ 2016-06-15 6:15 ` Keerthy
-1 siblings, 0 replies; 6+ messages in thread
From: Keerthy @ 2016-06-15 6:15 UTC (permalink / raw)
To: Keerthy, tony
Cc: robh+dt, mark.rutland, d-gerlach, nm, linux-omap, devicetree,
linux-arm-kernel, linux-kernel, Franklin S Cooper Jr,
Aparna Balasubramanian
On Wednesday 15 June 2016 11:43 AM, Keerthy wrote:
> From: Dave Gerlach <d-gerlach@ti.com>
>
> Based on the latest timing specifications for the TPS65218 from the data
> sheet, http://www.ti.com/lit/ds/symlink/tps65218.pdf, document SLDS206
> from November 2014, we must change the i2c bus speed to better fit within
> the minimum high SCL time required for proper i2c transfer.
>
> When running at 400khz, measurements show that SCL spends
> 0.8125 uS/1.666 uS high/low which violates the requirement for minimum
> high period of SCL provided in datasheet Table 7.6 which is 1 uS.
> Switching to 100khz gives us 5 uS/5 uS high/low which both fall above
> the minimum given values for 100 khz, 4.0 uS/4.7 uS high/low.
>
> Without this patch occasionally a voltage set operation from the kernel
> will appear to have worked but the actual voltage reflected on the PMIC
> will not have updated, causing problems especially with cpufreq that may
> update to a higher OPP without actually raising the voltage on DCDC2,
> leading to a hang.
I will resend with proper $Subject. Sorry for the noise. Please ignore
this patch.
>
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> Signed-off-by: Nishanth Menon <nm@ti.com>
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> Signed-off-by: Aparna Balasubramanian <aparnab@ti.com>
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
> arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
> index 18a3445..5f67001 100644
> --- a/arch/arm/boot/dts/am437x-sk-evm.dts
> +++ b/arch/arm/boot/dts/am437x-sk-evm.dts
> @@ -490,7 +490,7 @@
> status = "okay";
> pinctrl-names = "default";
> pinctrl-0 = <&i2c0_pins>;
> - clock-frequency = <400000>;
> + clock-frequency = <100000>;
>
> tps@24 {
> compatible = "ti,tps65218";
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218
@ 2016-06-15 6:15 ` Keerthy
0 siblings, 0 replies; 6+ messages in thread
From: Keerthy @ 2016-06-15 6:15 UTC (permalink / raw)
To: Keerthy, tony
Cc: robh+dt, mark.rutland, d-gerlach, nm, linux-omap, devicetree,
linux-arm-kernel, linux-kernel, Franklin S Cooper Jr,
Aparna Balasubramanian
On Wednesday 15 June 2016 11:43 AM, Keerthy wrote:
> From: Dave Gerlach <d-gerlach@ti.com>
>
> Based on the latest timing specifications for the TPS65218 from the data
> sheet, http://www.ti.com/lit/ds/symlink/tps65218.pdf, document SLDS206
> from November 2014, we must change the i2c bus speed to better fit within
> the minimum high SCL time required for proper i2c transfer.
>
> When running at 400khz, measurements show that SCL spends
> 0.8125 uS/1.666 uS high/low which violates the requirement for minimum
> high period of SCL provided in datasheet Table 7.6 which is 1 uS.
> Switching to 100khz gives us 5 uS/5 uS high/low which both fall above
> the minimum given values for 100 khz, 4.0 uS/4.7 uS high/low.
>
> Without this patch occasionally a voltage set operation from the kernel
> will appear to have worked but the actual voltage reflected on the PMIC
> will not have updated, causing problems especially with cpufreq that may
> update to a higher OPP without actually raising the voltage on DCDC2,
> leading to a hang.
I will resend with proper $Subject. Sorry for the noise. Please ignore
this patch.
>
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> Signed-off-by: Nishanth Menon <nm@ti.com>
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> Signed-off-by: Aparna Balasubramanian <aparnab@ti.com>
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
> arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
> index 18a3445..5f67001 100644
> --- a/arch/arm/boot/dts/am437x-sk-evm.dts
> +++ b/arch/arm/boot/dts/am437x-sk-evm.dts
> @@ -490,7 +490,7 @@
> status = "okay";
> pinctrl-names = "default";
> pinctrl-0 = <&i2c0_pins>;
> - clock-frequency = <400000>;
> + clock-frequency = <100000>;
>
> tps@24 {
> compatible = "ti,tps65218";
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218
@ 2016-06-15 6:15 ` Keerthy
0 siblings, 0 replies; 6+ messages in thread
From: Keerthy @ 2016-06-15 6:15 UTC (permalink / raw)
To: linux-arm-kernel
On Wednesday 15 June 2016 11:43 AM, Keerthy wrote:
> From: Dave Gerlach <d-gerlach@ti.com>
>
> Based on the latest timing specifications for the TPS65218 from the data
> sheet, http://www.ti.com/lit/ds/symlink/tps65218.pdf, document SLDS206
> from November 2014, we must change the i2c bus speed to better fit within
> the minimum high SCL time required for proper i2c transfer.
>
> When running at 400khz, measurements show that SCL spends
> 0.8125 uS/1.666 uS high/low which violates the requirement for minimum
> high period of SCL provided in datasheet Table 7.6 which is 1 uS.
> Switching to 100khz gives us 5 uS/5 uS high/low which both fall above
> the minimum given values for 100 khz, 4.0 uS/4.7 uS high/low.
>
> Without this patch occasionally a voltage set operation from the kernel
> will appear to have worked but the actual voltage reflected on the PMIC
> will not have updated, causing problems especially with cpufreq that may
> update to a higher OPP without actually raising the voltage on DCDC2,
> leading to a hang.
I will resend with proper $Subject. Sorry for the noise. Please ignore
this patch.
>
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> Signed-off-by: Nishanth Menon <nm@ti.com>
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> Signed-off-by: Aparna Balasubramanian <aparnab@ti.com>
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
> arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
> index 18a3445..5f67001 100644
> --- a/arch/arm/boot/dts/am437x-sk-evm.dts
> +++ b/arch/arm/boot/dts/am437x-sk-evm.dts
> @@ -490,7 +490,7 @@
> status = "okay";
> pinctrl-names = "default";
> pinctrl-0 = <&i2c0_pins>;
> - clock-frequency = <400000>;
> + clock-frequency = <100000>;
>
> tps at 24 {
> compatible = "ti,tps65218";
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-06-15 6:15 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2016-06-15 6:13 [tiL4.4-P PATCH] ARM: dts: am437x-sk-evm: Reduce i2c0 bus speed for tps65218 Keerthy
2016-06-15 6:13 ` Keerthy
2016-06-15 6:13 ` Keerthy
2016-06-15 6:15 ` Keerthy
2016-06-15 6:15 ` Keerthy
2016-06-15 6:15 ` Keerthy
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