diff mbox series

[v4,03/14] ARM: dts: dra7-mmc-iodelay: Add a new pinctrl group for clk line without pullup

Message ID 20180427120905.3665-4-kishon@ti.com
State Accepted
Commit ca2618b5d5b04a1e2e96244b00b54479cb6cf2b6
Headers show
Series [v4,01/14] ARM: dts: dra72-evm-common: Remove mmc specific pinmux | expand

Commit Message

Kishon Vijay Abraham I April 27, 2018, 12:08 p.m. UTC 
During a short period when the bus voltage is switched from 3.3v to 1.8v,
(to enumerate UHS mode), the mmc module is disabled and the mmc IO lines
are kept in a state according to the programmed pad mux pull type.

According to 4.2.4.2 Timing to Switch Signal Voltage in "SD Specifications
Part 1 Physical Layer Specification Version 5.00 February 22, 2016", the
host should hold CLK low for at least 5ms.

In order to keep the card line low during voltage switch, the pad mux of
mmc1_clk line should be configured to pull down.

Add a new pinctrl group for clock line without pullup to be used in boards
where mmc1_clk line is not connected to an external pullup.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

---
 arch/arm/boot/dts/dra7-mmc-iodelay.dtsi | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 arch/arm/boot/dts/dra7-mmc-iodelay.dtsi

-- 
2.17.0
diff mbox series

Patch

diff --git a/arch/arm/boot/dts/dra7-mmc-iodelay.dtsi b/arch/arm/boot/dts/dra7-mmc-iodelay.dtsi
new file mode 100644
index 000000000000..aa0947266526
--- /dev/null
+++ b/arch/arm/boot/dts/dra7-mmc-iodelay.dtsi
@@ -0,0 +1,19 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MMC IOdelay values for TI's DRA7xx SoCs.
+ * Copyright (C) 2018 Texas Instruments
+ * Author: Kishon Vijay Abraham I <kishon@ti.com>
+ */
+
+&dra7_pmx_core {
+	mmc1_pins_default_no_clk_pu: mmc1_pins_default_no_clk_pu {
+		pinctrl-single,pins = <
+			DRA7XX_CORE_IOPAD(0x3754, PIN_INPUT_PULLDOWN | MUX_MODE0) /* mmc1_clk.clk */
+			DRA7XX_CORE_IOPAD(0x3758, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc1_cmd.cmd */
+			DRA7XX_CORE_IOPAD(0x375c, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc1_dat0.dat0 */
+			DRA7XX_CORE_IOPAD(0x3760, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc1_dat1.dat1 */
+			DRA7XX_CORE_IOPAD(0x3764, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc1_dat2.dat2 */
+			DRA7XX_CORE_IOPAD(0x3768, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc1_dat3.dat3 */
+		>;
+	};
+};