Hi Sagar, On Thu, Feb 6, 2020 at 2:17 AM Sagar Kadam <sagar.ka...@sifive.com> wrote: > > Hello Bin, > > > -----Original Message----- > > From: Bin Meng <bmeng...@gmail.com> > > Sent: Tuesday, February 4, 2020 5:43 PM > > To: Sagar Kadam <sagar.ka...@sifive.com> > > Cc: U-Boot Mailing List <u-boot@lists.denx.de>; Rick Chen > > <r...@andestech.com>; Paul Walmsley ( Sifive) <paul.walms...@sifive.com>; > > Jagan Teki <ja...@amarulasolutions.com>; Anup Patel > > <anup.pa...@wdc.com> > > Subject: Re: [U-Boot Patch v2 1/4] fu540: dtsi: spi: add num-cs info to > > device > > tree > > > > Hi Sagar, > > > > On Wed, Jan 29, 2020 at 2:02 AM Sagar Shrikant Kadam > > <sagar.ka...@sifive.com> wrote: > > > > > > Add the number of chip select information to spi nodes which can be > > > used by spi-uclass for error handling if invalid cs number passed from > > > command. > > > > > > Signed-off-by: Sagar Shrikant Kadam <sagar.ka...@sifive.com> > > > --- > > > arch/riscv/dts/fu540-c000.dtsi | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/arch/riscv/dts/fu540-c000.dtsi > > > b/arch/riscv/dts/fu540-c000.dtsi index afa43c7..9c6ab21 100644 > > > --- a/arch/riscv/dts/fu540-c000.dtsi > > > +++ b/arch/riscv/dts/fu540-c000.dtsi > > > @@ -191,6 +191,7 @@ > > > clocks = <&prci PRCI_CLK_TLCLK>; > > > #address-cells = <1>; > > > #size-cells = <0>; > > > + num-cs = <1>; > > > > Why is this necessary? I can't find the codes that handle the num-cs > > property. > The code handling num-cs is a part of patch 2. I intended to keep it separate > thinking better to isolate dt and c files patches. Please let me know if I > need > to keep it together. > > > In the SiFive SPI driver, num_cs is determined from register > > SIFIVE_SPI_REG_CSDEF. > > > The SiFive SPI driver does read the num_cs defined in the register you > mentioned. > but it's hard defined with cs_width, eg: QSPI0 = 1, QSPI1 = 4, QSPI2 = 1. > I have added the option after sifive_spi_init_hw to read from device tree as > well > so that if the user want's to change the chip select's (less than that > defined in > SIFIVE_SPI_REG_CSDEF) then it can be done in hifive-unleashed-a00.dtsi > Please let me know your thoughts over here. >
My understanding is that "nun-cs" represents the actual number of chip selects a controller supports. In your patch you changed all 3 controllers num-cs to 1, but they should be 1/4/1 respectively. I see changes are made in fu540-c000.dtsi. Was such change discussed in the kernel DT community? Is this change actually fixing any issue with what we saw on the Unleashed board? Regards, Bin
