| Message ID | 20231205202900.4617-2-CFSworks@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND] arm64: dts: rockchip: Fix eMMC Data Strobe PD | expand |
On Tue, 5 Dec 2023 12:29:00 -0800, Sam Edwards wrote: > JEDEC standard JESD84-B51 defines the eMMC Data Strobe line, which is > currently used only in HS400 mode, as a device->host clock signal that > "is used only in read operation. The Data Strobe is always High-Z (not > driven by the device and pulled down by RDS) or Driven Low in write > operation, except during CRC status response." RDS is a pull-down > resistor specified in the 10K-100K ohm range. Thus per the standard, the > Data Strobe is always pulled to ground (by the eMMC and/or RDS) during > write operations. > > [...] Applied, thanks! [1/1] arm64: dts: rockchip: Fix eMMC Data Strobe PD commit: 37f3d6108730713c411827ab4af764909f4dfc78 Best regards,
diff --git a/arch/arm64/boot/dts/rockchip/rk3588s-pinctrl.dtsi b/arch/arm64/boot/dts/rockchip/rk3588s-pinctrl.dtsi index 63151d9d2377..30db12c4fc82 100644 --- a/arch/arm64/boot/dts/rockchip/rk3588s-pinctrl.dtsi +++ b/arch/arm64/boot/dts/rockchip/rk3588s-pinctrl.dtsi @@ -369,7 +369,7 @@ emmc_cmd: emmc-cmd { emmc_data_strobe: emmc-data-strobe { rockchip,pins = /* emmc_data_strobe */ - <2 RK_PA2 1 &pcfg_pull_none>; + <2 RK_PA2 1 &pcfg_pull_down>; }; };
JEDEC standard JESD84-B51 defines the eMMC Data Strobe line, which is currently used only in HS400 mode, as a device->host clock signal that "is used only in read operation. The Data Strobe is always High-Z (not driven by the device and pulled down by RDS) or Driven Low in write operation, except during CRC status response." RDS is a pull-down resistor specified in the 10K-100K ohm range. Thus per the standard, the Data Strobe is always pulled to ground (by the eMMC and/or RDS) during write operations. Evidently, the eMMC host controller in the RK3588 considers an active voltage on the eMMC-DS line during a write to be an error. The default (i.e. hardware reset, and Rockchip BSP) behavior for the RK3588 is to activate the eMMC-DS pin's builtin pull-down. As a result, many RK3588 board designers do not bother adding a dedicated RDS resistor, instead relying on the RK3588's internal bias. The current devicetree, however, disables this bias (`pcfg_pull_none`), breaking HS400-mode writes for boards without a dedicated RDS, but with an eMMC chip that chooses to High-Z (instead of drive-low) the eMMC-DS line. (The Turing RK1 is one such board.) Fix this by changing the bias in the (common) emmc_data_strobe case to reflect the expected hardware/BSP behavior. This is unlikely to cause regressions elsewhere: the pull-down is only relevant for High-Z eMMCs, and if this is redundant with a (dedicated) RDS resistor, the effective result is only a lower resistance to ground -- where the range of tolerance is quite high. If it does, it's better fixed in the specific devicetrees. Fixes: d85f8a5c798d5 ("arm64: dts: rockchip: Add rk3588 pinctrl data") Signed-off-by: Sam Edwards <CFSworks@gmail.com> --- arch/arm64/boot/dts/rockchip/rk3588s-pinctrl.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)