pajenicko_picopad: request 62.5MHz for the ST7789, not 60MHz - #11291
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pajenicko_picopad: request 62.5MHz for the ST7789, not 60MHz#11291lynt-smitka wants to merge 1 commit into
lynt-smitka wants to merge 1 commit into
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The PL022 SPI block can only divide clk_peri (125MHz) by even integers, and the driver rounds DOWN: requesting 60MHz yields an actual 31.25MHz clock - half the display bandwidth for every user of this board. Requesting exactly clk_peri/2 = 62.5MHz gets full speed; the ST7789 in this wiring handles it (device-measured: a full-screen 320x240 push drops from 47.4ms to the ~20ms wire floor, matching the sibling pajenicko_picopad_game testbed config that already requests 62500000).
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The SPI clock can only be
clk_peri(125 MHz) divided by an even number - 62.5, 31.25, 20.8 MHz, and the SDK picks the fastest of those that does not exceed what the board asked for. Asking for 60 MHz therefore runs the display at 31.25 MHz, half the bandwidth it could have. The panel has been running reliably at 62.5 MHz on this board for a long time, and at that rate a full-screen 320x240 push drops from 47.4 ms to about 20 ms.