[ Trimming recipients list ]
On 21/03/2023 13:26, Christian Hewitt wrote:
> To Jerôme's point; unless you've tweaked it upstream will be running
> at 100MHz and the vendor kernel will be 200MHz, and maybe with other
> high-speed modes activated.
As far as I could tell:
For mainline, arch/arm64/boot/dts/amlogic/meson-g12a-sei510.dts
bus-width = <4>;
cap-sd-highspeed;
sd-uhs-sdr50;
max-frequency = <100000000>;
For vendor, common/arch/arm64/boot/dts/amlogic/mesong12a_sei.dtsi
bus-width = <4>;
cap-sd-highspeed;
cap-mmc-highspeed;
max-frequency = <100000000>;
vendor DTS has the following child node:
sdio {
pinname = "sdio";
ocr_avail = <0x200080>; /**VDD voltage 3.3 ~ 3.4 */
/* max_req_size = <0x20000>; */ /**128KB*/
max_req_size = <0x400>;
card_type = <3>;
/* 3:sdio device(ie:sdio-wifi),
* 4:SD combo (IO+mem) card
*/
dmode = "pio";
};
Maybe the vendor kernel uses the above information to "boost"
the performance of the SDIO-based WiFi adapter?
> Most upstream device-trees are running a
> conservative/safe configuration at 50MHz to avoid past speed-related
> issues. As stability has improved over time most boards could be run
> at faster speeds, but 'performance' is such subjective topic that it
> would probably need a large amount of testing to convince people to
> change the current defaults. That said (FWIW) I've bumped all boards
> in my tree that consume the gx-p2xx-q2xx dtsi to 100MHz without any
> attributable issues being flagged by users.
