Re: [PATCH] common: spl: spl_dfu.c: Fix warning associated with PCI subclass_code

[Anshul Dalal <anshuld@ti.com>]

On Thu Mar 5, 2026 at 4:08 PM IST, Siddharth Vadapalli wrote:
> The subclass_code member of the pci_ep_header structure is a 1-byte
> field. The macro PCI_CLASS_MEMORY_RAM is a concetation of baseclass_code
> and subclass_code as follows:
> 	PCI_BASE_CLASS_MEMORY: 0x05
> 	Subclass Code for RAM: 0x00
> 	PCI_CLASS_MEMORY_RAM:  0x0500
> Hence, instead of extracting it via an implicity type conversion from int
> to u8 which throws a warning, explicitly mask the bits to extract the
> subclass_code.
>
> Fixes: cde77583cf0b ("spl: Add support for Device Firmware Upgrade (DFU) over PCIe")
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>

I was able to reproduce the issue on am62x_evm_a53_defconfig with the
following diff:

	diff --git a/arch/arm/mach-k3/include/mach/am62_spl.h b/arch/arm/mach-k3/include/mach/am62_spl.h
	index 2c9139d2cc0..07ae5e99e49 100644
	--- a/arch/arm/mach-k3/include/mach/am62_spl.h
	+++ b/arch/arm/mach-k3/include/mach/am62_spl.h
	@@ -12,6 +12,7 @@
	 #define BOOT_DEVICE_OSPI		0x01
	 #define BOOT_DEVICE_QSPI		0x02
	 #define BOOT_DEVICE_SPI			0x03
	+#define BOOT_DEVICE_PCIE			0x03
	 #define BOOT_DEVICE_CPGMAC		0x04
	 #define BOOT_DEVICE_ETHERNET_RGMII	0x04
	 #define BOOT_DEVICE_ETHERNET_RMII	0x05
	diff --git a/configs/am62x_evm_a53_defconfig b/configs/am62x_evm_a53_defconfig
	index 281fa3fea15..a828ad164f1 100644
	--- a/configs/am62x_evm_a53_defconfig
	+++ b/configs/am62x_evm_a53_defconfig
	@@ -1,4 +1,9 @@
	 CONFIG_ARM=y
	+CONFIG_SPL_PCI_DFU=y
	+CONFIG_SPL_PCI_ENDPOINT=y
	+CONFIG_SPL_PCI_DFU_SPL_LOAD_FIT_ADDRESS=0x0
	+CONFIG_SPL_PCI_DFU_VENDOR_ID=0x0
	+CONFIG_SPL_PCI_DFU_DEVICE_ID=0x0
	 CONFIG_ARCH_K3=y
	 CONFIG_SYS_MALLOC_F_LEN=0x8000
	 CONFIG_TI_COMMON_CMD_OPTIONS=y

The patch looks good to me and fixes the build warning :)

Tested-by: Anshul Dalal <anshuld@ti.com>

> ---
>
> Hello,
>
> This patch is based on commit
> f473a453b0c kbuild: Drop phandle from diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1of the master branch of U-Boot.
>
> Regards,
> Siddharth.
>
>  common/spl/spl_dfu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/common/spl/spl_dfu.c b/common/spl/spl_dfu.c
> index b09f82790c9..7d21bb4d16a 100644
> --- a/common/spl/spl_dfu.c
> +++ b/common/spl/spl_dfu.c
> @@ -64,7 +64,7 @@ static int dfu_over_pcie(void)
>  	hdr.deviceid = CONFIG_SPL_PCI_DFU_DEVICE_ID;
>  	hdr.vendorid = CONFIG_SPL_PCI_DFU_VENDOR_ID;
>  	hdr.baseclass_code = PCI_BASE_CLASS_MEMORY;
> -	hdr.subclass_code = PCI_CLASS_MEMORY_RAM;
> +	hdr.subclass_code = PCI_CLASS_MEMORY_RAM & 0xff;
>  
>  	ret = pci_ep_write_header(dev, fn, &hdr);
>  	if (ret) {