On Tue, Apr 05, 2022 at 03:09:35PM +0200, Geert Uytterhoeven wrote: > Hi Niklas, > > On Tue, Apr 5, 2022 at 3:03 PM Niklas Cassel <Niklas.Cassel@xxxxxxx> wrote: > > On Tue, Apr 05, 2022 at 02:26:53PM +0200, Geert Uytterhoeven wrote: > > > On Tue, Mar 8, 2022 at 2:30 PM Niklas Cassel <Niklas.Cassel@xxxxxxx> wrote: > > > > From: Niklas Cassel <niklas.cassel@xxxxxxx> > > > > According to the K210 Standalone SDK Programming guide: > > > > https://canaan-creative.com/wp-content/uploads/2020/03/kendryte_standalone_programming_guide_20190311144158_en.pdf > > > > > > > > Section 15.4.3.3: > > > > SPI0 and SPI1 supports: standard, dual, quad and octal transfers. > > > > SPI3 supports: standard, dual and quad transfers (octal is not supported). > > > > > > > > In order to support quad transfers (Quad SPI), SPI3 must have four IO wires > > > > connected to the SPI flash. > > > > > > > > Update the device tree to specify the correct bus width. > > > > > > > > Tested on maix bit, maix dock and maixduino, which all have the same > > > > SPI flash (gd25lq128d) connected to SPI3. maix go is untested, but it > > > > would not make sense for this k210 board to be designed differently. > > > > > > > > Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx> > > > > --- > > > > Changes since v1: > > > > -Add the new properties directly after spi-max-frequency for all DT board > > > > files. > > > > > > Thanks for your patch, which is now commit 6846d656106add3a ("riscv: > > > dts: canaan: Fix SPI3 bus width") in v5.18-rc1. > > > > > > > --- a/arch/riscv/boot/dts/canaan/sipeed_maix_bit.dts > > > > +++ b/arch/riscv/boot/dts/canaan/sipeed_maix_bit.dts > > > > @@ -203,6 +203,8 @@ flash@0 { > > > > compatible = "jedec,spi-nor"; > > > > reg = <0>; > > > > spi-max-frequency = <50000000>; > > > > + spi-tx-bus-width = <4>; > > > > + spi-rx-bus-width = <4>; > > > > m25p,fast-read; > > > > broken-flash-reset; > > > > }; > > > > > > On MAiX BiT, I get: > > > > > > +spi spi1.0: setup: ignoring unsupported mode bits a00 > > > spi-nor spi1.0: gd25lq128d (16384 Kbytes) > > > > The device tree is supposed to describe the hardware. > > > > The Synopsys SPI controller and the Gigadevice SPI flash both support quad > > transfers. > > > > It would be incorrect to adapt the device tree based on current limitations > > of the drivers/spi/spi-dw-core.c driver. > > > > Likewise, we shouldn't need to update the device tree if the dwc driver > > ever adds support for quad transfers. > > I fully agree with that. > > I was just wondering whether work is underway to add quad support > to the SPI controller driver. Hello Geert, Not planned from my side :( I'm actually quite surprised that the dwc driver doesn't support it yet, considering how popular this IP is, and considering that a lot for SPI drivers (for other SPI controllers) support it already. FWIW, neither nommu_k210_defconfig nor nommu_k210_sdcard_defconfig have CONFIG_MTD_SPI_NOR set, so at least the only people who will see the warning is people who are explicitly enabling support for the SPI flash. Kind regards, Niklas
