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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Dave Gerlach <d-gerlach@ti.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Tony Lindgren <tony@atomide.com>, Sasha Levin <sashal@kernel.org>,
	linux-omap@vger.kernel.org, devicetree@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 03/11] ARM: dts: am43x-epos-evm: Reduce i2c0 bus speed for tps65218
Date: Tue, 10 Aug 2021 10:16:16 -0400	[thread overview]
Message-ID: <20210810141625.3118097-3-sashal@kernel.org> (raw)
In-Reply-To: <20210810141625.3118097-1-sashal@kernel.org>

From: Dave Gerlach <d-gerlach@ti.com>

[ Upstream commit 20a6b3fd8e2e2c063b25fbf2ee74d86b898e5087 ]

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: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm/boot/dts/am43x-epos-evm.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/am43x-epos-evm.dts b/arch/arm/boot/dts/am43x-epos-evm.dts
index 02bbdfb3f258..0cc3ac6566c6 100644
--- a/arch/arm/boot/dts/am43x-epos-evm.dts
+++ b/arch/arm/boot/dts/am43x-epos-evm.dts
@@ -590,7 +590,7 @@ &i2c0 {
 	status = "okay";
 	pinctrl-names = "default";
 	pinctrl-0 = <&i2c0_pins>;
-	clock-frequency = <400000>;
+	clock-frequency = <100000>;
 
 	tps65218: tps65218@24 {
 		reg = <0x24>;
-- 
2.30.2


  parent reply	other threads:[~2021-08-10 14:21 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-10 14:16 [PATCH AUTOSEL 4.19 01/11] dmaengine: xilinx_dma: Fix read-after-free bug when terminating transfers Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 02/11] dmaengine: usb-dmac: Fix PM reference leak in usb_dmac_probe() Sasha Levin
2021-08-10 14:16 ` Sasha Levin [this message]
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 04/11] dmaengine: of-dma: router_xlate to return -EPROBE_DEFER if controller is not yet available Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 05/11] scsi: megaraid_mm: Fix end of loop tests for list_for_each_entry() Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 06/11] scsi: scsi_dh_rdac: Avoid crash during rdac_bus_attach() Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 07/11] scsi: core: Avoid printing an error if target_alloc() returns -ENXIO Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 08/11] ARM: dts: nomadik: Fix up interrupt controller node names Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 10/11] Revert "ACPICA: Fix memory leak caused by _CID repair function" Sasha Levin
2021-08-10 14:16 ` [PATCH AUTOSEL 4.19 11/11] net: usb: lan78xx: don't modify phy_device state concurrently Sasha Levin

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