Re: [PATCH 4/6] mips: bmips: setup: make CBR address configurable

Florian Fainelli
2024-05-03T19:09:05Z

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On 5/3/24 06:54, Christian Marangi wrote:
> Add support to provide CBR address from DT to handle broken
> SoC/Bootloader that doesn't correctly init it. This permits to use the
> RAC flush even in these condition.
>
> To provide a CBR address from DT, the property "mips-cbr-reg" needs to
> be set in the "cpus" node. On DT init, this property presence will be
> checked and will set the bmips_cbr_addr value accordingly. Also
> bmips_rac_flush_disable will be set to false as RAC flush can be
> correctly supported.
>
> The CBR address from DT will be applied only if the CBR address from the
> registers is 0, if the CBR address from the registers is not 0 and
> is not equal to the one set in DT (if provided) a WARN is printed.
>
> To ALWAYS overwrite the CBR address the additional property
> "mips-broken-cbr-reg" needs to be set.
>
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> ---
> arch/mips/bmips/setup.c | 30 +++++++++++++++++++++++++++---
> 1 file changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
> index 18561d426f89..bef84677248e 100644
> --- a/arch/mips/bmips/setup.c
> +++ b/arch/mips/bmips/setup.c
> @@ -34,7 +34,11 @@
> #define REG_BCM6328_OTP ((void __iomem *)CKSEG1ADDR(0x1000062c))
> #define BCM6328_TP1_DISABLED BIT(9)
>
> -/* CBR addr doesn't change and we can cache it */
> +/*
> + * CBR addr doesn't change and we can cache it.
> + * For broken SoC/Bootloader CBR addr might also be provided via DT
> + * with "mips-cbr-reg" in the "cpus" node.
> + */
> void __iomem *bmips_cbr_addr;
> extern bool bmips_rac_flush_disable;
>
> @@ -212,8 +216,28 @@ void __init device_tree_init(void)
>
> /* Disable SMP boot unless both CPUs are listed in DT and !disabled */
> np = of_find_node_by_name(NULL, "cpus");
> - if (np && of_get_available_child_count(np) <= 1)
> - bmips_smp_enabled = 0;
> + if (np) {

Please reduce the indentation with early return/gotos. There might also
be a need to do some validation that the CBR is at least outside of the
DRAM window, that is we cannot blindly trust the DT to have gotten the
CBR right IMHO.
--
Florian

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