Thread (2 messages) flat view 2 messages, 2 authors, 2021-12-23

Re: Issue with booting multi_v5_defconfig kernel with GCC 11

From: Arnd Bergmann <arnd@arndb.de>
Date: 2021-12-23 21:48:47
Also in: lkml

On Thu, Dec 23, 2021 at 6:58 PM Nathan Chancellor [off-list ref] wrote:
da850_evm_config_emac: soc_info: c0dd7288
da850_evm_config_emac: emac_pdata: 00000000

I don't really see how that is possible, as I can see this member
assigned in the davinci_soc_info_* variables but maybe there is some
race during initialization or problem because the QEMU machine is not
one of these machines?
Right, the problem is that da850_evm_config_emac() gets called
unconditionally for all machines, but davinci_soc_info only gets
populated on davinci machines.
quoted hunk ↗ jump to hunk
I think that the GCC commit just makes it so that the rmii_en member is
read earlier, rather than at the point of use.

Regardless, something like this resolves this panic for me but I have no
idea if it is proper or not, hence just the report :)
diff --git a/arch/arm/mach-davinci/board-da850-evm.c b/arch/arm/mach-davinci/board-da850-evm.c
index 428012687a80..7f7f6bae21c2 100644
--- a/arch/arm/mach-davinci/board-da850-evm.c
+++ b/arch/arm/mach-davinci/board-da850-evm.c
@@ -1101,11 +1101,13 @@ static int __init da850_evm_config_emac(void)
        int ret;
        u32 val;
        struct davinci_soc_info *soc_info = &davinci_soc_info;
-       u8 rmii_en = soc_info->emac_pdata->rmii_en;
+       u8 rmii_en;

        if (!machine_is_davinci_da850_evm())
                return 0;

+       rmii_en = soc_info->emac_pdata->rmii_en;
+
        cfg_chip3_base = DA8XX_SYSCFG0_VIRT(DA8XX_CFGCHIP3_REG);

        val = __raw_readl(cfg_chip3_base);
This is the correct fix.

Fixes: bae105879f2f ("davinci: DA850/OMAP-L138 EVM: implement
autodetect of RMII PHY")
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

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