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Sky Huang
058bd6c9d3
8mA driving will cause overshoot issue on SPI NAND. Change it to 4mA. - Reference: https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/003744197aa3a587828b4330ab1112ebdb9e840a On Linux mainline (mt7986.dtsi), spi's source clock is: clocks = <&topckgen CLK_TOP_MPLL_D2>, which is 208MHz. Usable clock division will be: - 208/4=52MHz - 208/6~=35MHz - 208/8=26MHz and so on If we specify 50MHz for spi-max-frequency, it will actually run under about 35MHz. Most SPI NAND & NOR flashes are capable of running with more than 52MHz, include Micorn MT29F4G01ABAFDWB on ZyXEL EX5601. [Ref: #18752] To reach highest performance on mt7986, use spi-max-frequency = <520000000>. Basically, this setting should work on all mt7986 PCBs since most mt7986 boards follow reference design. However, other boards needs further test to guarantee stability. Signed-off-by: Sky Huang <SkyLake.Huang@mediatek.com> Tested-by: Aleksander Jan Bajkowski <olek2@wp.pl> Link: https://github.com/openwrt/openwrt/pull/18813 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>