Hi Sagar,
On Thu, Feb 6, 2020 at 2:17 AM Sagar Kadam sagar.kadam@sifive.com wrote:
Hello Bin,
-----Original Message----- From: Bin Meng bmeng.cn@gmail.com Sent: Tuesday, February 4, 2020 5:43 PM To: Sagar Kadam sagar.kadam@sifive.com Cc: U-Boot Mailing List u-boot@lists.denx.de; Rick Chen rick@andestech.com; Paul Walmsley ( Sifive) paul.walmsley@sifive.com; Jagan Teki jagan@amarulasolutions.com; Anup Patel anup.patel@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.kadam@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.kadam@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