Re: [PATCH v2 4/4] arm64: dts: rockchip: use cs-gpios for cros_ec_spi
From: Brian Norris <hidden>
Date: 2017-06-13 17:50:49
Also in:
linux-arm-kernel, linux-rockchip, lkml
On Tue, Jun 13, 2017 at 01:25:43PM +0800, Jeffy Chen wrote:
The cros_ec requires CS line to be active after last message. But the CS would be toggled when powering off/on rockchip spi, which breaks ec xfer. Use GPIO CS to prevent that.
I suppose this change is fine. (At least, I don't have a good reason not to do this.) But I still wonder whether this is something that the SPI core can be expected to handle. drivers/mfd/cros_ec_spi.c already sets the appropriate trans->cs_change bits, to ensure CS remains active in between certain messages (all under spi_bus_lock()). But you're suggesting that your bus controller may deassert CS if you runtime suspend the device (e.g., in between messages). So, is your controller just peculiar? Or should the SPI core avoid autosuspending the bus controller when it's been instructed to keep CS active? Any thoughts Mark?
quoted hunk ↗ jump to hunk
Signed-off-by: Jeffy Chen <redacted> --- Changes in v2: Fix wrong pinconf for spi5_cs0. arch/arm64/boot/dts/rockchip/rk3399-gru.dtsi | 6 ++++++ 1 file changed, 6 insertions(+)diff --git a/arch/arm64/boot/dts/rockchip/rk3399-gru.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-gru.dtsi index eb50593..b34a51d 100644 --- a/arch/arm64/boot/dts/rockchip/rk3399-gru.dtsi +++ b/arch/arm64/boot/dts/rockchip/rk3399-gru.dtsi@@ -790,6 +790,8 @@ ap_i2c_audio: &i2c8 { &spi5 { status = "okay"; + cs-gpios = <&gpio2 23 GPIO_ACTIVE_HIGH>;
This isn't actually true; it's not active high, it's active low. I guess it
doesn't really matter because the SPI framework uses the gpio_* APIs, which
don't account for the ACTIVE_* flags, and it has separate flags for uncommon
device polarity ("spi-cs-high").
Brian
quoted hunk ↗ jump to hunk
+ cros_ec: ec@0 { compatible = "google,cros-ec-spi"; reg = <0>;@@ -813,6 +815,10 @@ ap_i2c_audio: &i2c8 { }; }; +&spi5_cs0 { + rockchip,pins = <RK_GPIO2 23 RK_FUNC_GPIO &pcfg_output_high>; +}; + &tsadc { status = "okay";-- 2.1.4
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