[Performance regression] BCM4359/9 on S905X2

[Marc Gonzalez]

[ 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.