2020-08-29 23:18:24

by Tobias Schramm

Subject: [PATCH 1/1] ARM: dts: bcm2711: Enable ddr modes on emmc2 controller

This patch enables ddr modes for eMMC and SD storage on emmc2,
doubling transfer speed. Previously only single data rate modes were
used, wasting half the available throughput.
The bcm2711 supports both SD and eMMC storage using ddr modes. Testing
show that pcb layout of the Raspberry Pi 4 can support them, too.

Signed-off-by: Tobias Schramm <[email protected]>
---
arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
index 222d7825e1ab..8b61e258e906 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
@@ -191,6 +191,8 @@ &emmc2 {
vqmmc-supply = <&sd_io_1v8_reg>;
vmmc-supply = <&sd_vcc_reg>;
broken-cd;
+ mmc-ddr-3_3v;
+ sd-uhs-ddr50;
status = "okay";
};

--
2.28.0

2020-08-31 23:02:18

by Florian Fainelli

Subject: Re: [PATCH 1/1] ARM: dts: bcm2711: Enable ddr modes on emmc2 controller

On 8/29/2020 4:15 PM, Tobias Schramm wrote:
> This patch enables ddr modes for eMMC and SD storage on emmc2,
> doubling transfer speed. Previously only single data rate modes were
> used, wasting half the available throughput.
> The bcm2711 supports both SD and eMMC storage using ddr modes. Testing
> show that pcb layout of the Raspberry Pi 4 can support them, too.
>
> Signed-off-by: Tobias Schramm <[email protected]>

This depends on Stefan's patch here:

https://lore.kernel.org/linux-arm-kernel/[email protected]/

I am fine with us taking the DTS patch, as long as they all land in 5.10
at some point.

> ---
> arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> index 222d7825e1ab..8b61e258e906 100644
> --- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> +++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> @@ -191,6 +191,8 @@ &emmc2 {
> vqmmc-supply = <&sd_io_1v8_reg>;
> vmmc-supply = <&sd_vcc_reg>;
> broken-cd;
> + mmc-ddr-3_3v;
> + sd-uhs-ddr50;
> status = "okay";
> };
>
>

--
Florian