[PATCH v2 0/1] ARM: dts: mmp2-olpc-xo-1-75: clear the warnings when make dtbs

[Zhen Lei <thunder.leizhen@huawei.com>]

v1 --> v2:
Update the patch description and subject.

I'm going to describe the detailed analysis here, because I don't want the
patch description to be too long.

0) make ARCH=arm CROSS_COMPILE=arm-linux-gnu- dtbs -j24 2>err.txt
   vim err.txt
arch/arm/boot/dts/mmp2.dtsi:472.23-480.6: Warning (spi_bus_bridge): /soc/apb@d4000000/spi@d4037000: incorrect #address-cells for SPI bus
  also defined at arch/arm/boot/dts/mmp2-olpc-xo-1-75.dts:225.7-237.3
arch/arm/boot/dts/mmp2.dtsi:472.23-480.6: Warning (spi_bus_bridge): /soc/apb@d4000000/spi@d4037000: incorrect #size-cells for SPI bus
  also defined at arch/arm/boot/dts/mmp2-olpc-xo-1-75.dts:225.7-237.3
arch/arm/boot/dts/mmp2-olpc-xo-1-75.dtb: Warning (spi_bus_reg): Failed prerequisite 'spi_bus_bridge'

1) mmp2.dtsi is included by mmp2-olpc-xo-1-75.dts, and the content of ssp3
node is:

arch/arm/boot/dts/mmp2.dtsi:472
ssp3: spi@d4037000 {
	compatible = "marvell,mmp2-ssp";
	reg = <0xd4037000 0x1000>;
	clocks = <&soc_clocks MMP2_CLK_SSP2>;
	interrupts = <20>;
	#address-cells = <1>;
	#size-cells = <0>;                        <-------- #size-cells = <0>
	status = "disabled";
};

arch/arm/boot/dts/mmp2-olpc-xo-1-75.dts:225
&ssp3 {
        /delete-property/ #address-cells;         <-------- #address-cells is deleted here
        /delete-property/ #size-cells;            <-------- #size-cells is deleted here
        spi-slave;
        status = "okay";
        ready-gpios = <&gpio 125 GPIO_ACTIVE_HIGH>;

        slave {
                compatible = "olpc,xo1.75-ec";
                spi-cpha;
                cmd-gpios = <&gpio 155 GPIO_ACTIVE_HIGH>;
        };
};

2) scripts/dtc/checks.c: check_spi_bus_bridge() requires that the values of both
#address-cells and #size-cells must be zero, when the node have "spi-slave" property.
	if (get_property(node, "spi-slave"))
                spi_addr_cells = 0;
        if (node_addr_cells(node) != spi_addr_cells)
                FAIL(c, dti, node, "incorrect #address-cells for SPI bus");
        if (node_size_cells(node) != 0)
                FAIL(c, dti, node, "incorrect #size-cells for SPI bus");

3) But both #address-cells and #size-cells properties are deleted. So the return value
of node_addr_cells(node) is 2, and the return value of node_size_cells(node) is 1.
#define node_addr_cells(n) \
        (((n)->addr_cells == -1) ? 2 : (n)->addr_cells)
#define node_size_cells(n) \
        (((n)->size_cells == -1) ? 1 : (n)->size_cells)

4) The checks in 2) failed, so the above 0) warnings is displayed.



v1:
Patch 5/6.
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2341407.html

Zhen Lei (1):
  ARM: dts: mmp2-olpc-xo-1-75: clear the warnings when make dtbs

 arch/arm/boot/dts/mmp2-olpc-xo-1-75.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
1.8.3