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Date:   Tue, 4 Apr 2023 18:09:00 +0200
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Subject: Re: [Performance regression] BCM4359/9 on S905X2
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To:     Christian Hewitt <christian@hewittfamily.org.uk>
Cc:     Linux Wireless <linux-wireless@vger.kernel.org>,
        MMC <linux-mmc@vger.kernel.org>,
        AML <linux-amlogic@lists.infradead.org>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Pierre-Hugues Husson <phh@phh.me>
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 <EEE9FD80-C106-4A9B-AA8D-5C151E540CFD@hewittfamily.org.uk>
From:   Marc Gonzalez <marc.w.gonzalez@free.fr>
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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.