Re: [PATCH 4/5] MIPS: OCTEON: program L2C_CTL, not L2C_CFG, on OCTEON II

[Thomas Bogendoerfer <tsbogend@alpha.franken.de>]

On Tue, Sep 15, 2026 at 07:12:47AM +0000, Orgad Shaneh wrote:
> cvmx_helper_initialize_packet_io_global() sets the L2 arbitration modes
> by rewriting L2C_CFG. That register (0x1180080000000) does not exist on
> OCTEON II; there the L2 controller is configured through L2C_CTL
> (0x1180080800000), whose corresponding fields are rsp_arb_mode and
> xmc_arb_mode.
> 
> On a CN6335 the stray write hung the board hard when this function ran -
> no exception, no watchdog, just a dead console.
> 
> Keep the L2C_CFG write for CN3XXX/CN5XXX and program L2C_CTL on CN6XXX
> with the values the vendor SDK uses there (rsp_arb_mode 1,
> xmc_arb_mode 0), which is the same trade the existing code makes for
> the older parts: keep IO blocks from being starved under high L2 load.
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Orgad Shaneh <orgads@gmail.com>
> ---
> diff --git a/arch/mips/cavium-octeon/executive/cvmx-helper.c b/arch/mips/cavium-octeon/executive/cvmx-helper.c
> --- a/arch/mips/cavium-octeon/executive/cvmx-helper.c
> +++ b/arch/mips/cavium-octeon/executive/cvmx-helper.c
> @@ -1014,7 +1014,6 @@ int cvmx_helper_initialize_packet_io_global(void)
>  {
>  	int result = 0;
>  	int interface;
> -	union cvmx_l2c_cfg l2c_cfg;
>  	const int num_interfaces = cvmx_helper_get_number_of_interfaces();
>  
>  	/*
> @@ -1029,10 +1028,21 @@ int cvmx_helper_initialize_packet_io_global(void)
>  	 * to the cores. This avoids conditions where IO blocks might
>  	 * be starved under very high L2 loads.
>  	 */
> -	l2c_cfg.u64 = cvmx_read_csr(CVMX_L2C_CFG);
> -	l2c_cfg.s.lrf_arb_mode = 0;
> -	l2c_cfg.s.rfb_arb_mode = 0;
> -	cvmx_write_csr(CVMX_L2C_CFG, l2c_cfg.u64);
> +	if (OCTEON_IS_MODEL(OCTEON_CN6XXX)) {
> +		union cvmx_l2c_ctl l2c_ctl;
> +
> +		l2c_ctl.u64 = cvmx_read_csr(CVMX_L2C_CTL);
> +		l2c_ctl.s.rsp_arb_mode = 1;
> +		l2c_ctl.s.xmc_arb_mode = 0;
> +		cvmx_write_csr(CVMX_L2C_CTL, l2c_ctl.u64);
> +	} else {
> +		union cvmx_l2c_cfg l2c_cfg;
> +
> +		l2c_cfg.u64 = cvmx_read_csr(CVMX_L2C_CFG);
> +		l2c_cfg.s.lrf_arb_mode = 0;
> +		l2c_cfg.s.rfb_arb_mode = 0;
> +		cvmx_write_csr(CVMX_L2C_CFG, l2c_cfg.u64);
> +	}
>  
>  	cvmx_pko_initialize_global();
>  	for (interface = 0; interface < num_interfaces; interface++) {
> -- 
> 2.47.0

applied to mips-next

Thomas.

-- 
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