linux-kernel - Re: [PATCH 2/5] of: reserved_mem: Implement alloc-{bottom-up,top-down}

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Date:   Wed, 17 May 2023 21:28:24 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Stephan Gerhold <stephan@...hold.net>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        devicetree@...r.kernel.org, devicetree-spec@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/5] of: reserved_mem: Implement
 alloc-{bottom-up,top-down}



On 15.05.2023 12:12, Stephan Gerhold wrote:
> Use memblock_set_bottom_up() to specify an explicit allocation order for
> dynamic reservations with "alloc-ranges". Since the default value varies
> between architectures the previous value is saved and restored after
> trying the allocations.
> 
> If neither alloc-bottom-up or alloc-top-down are specified the previous
> implementation-defined allocation order is preserved.
> 
> Signed-off-by: Stephan Gerhold <stephan@...hold.net>
> ---
Acked-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad
>  drivers/of/of_reserved_mem.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 948efa9f99e3..6443140deacf 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -89,7 +89,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
>  	phys_addr_t base = 0, align = 0, size;
>  	int len;
>  	const __be32 *prop;
> -	bool nomap;
> +	bool nomap, prev_bottom_up;
>  	int ret;
>  
>  	prop = of_get_flat_dt_prop(node, "size", &len);
> @@ -130,6 +130,12 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
>  			return -EINVAL;
>  		}
>  
> +		prev_bottom_up = memblock_bottom_up();
> +		if (of_get_flat_dt_prop(node, "alloc-bottom-up", NULL))
> +			memblock_set_bottom_up(true);
> +		if (of_get_flat_dt_prop(node, "alloc-top-down", NULL))
> +			memblock_set_bottom_up(false);
> +
>  		base = 0;
>  
>  		while (len > 0) {
> @@ -148,6 +154,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
>  			len -= t_len;
>  		}
>  
> +		memblock_set_bottom_up(prev_bottom_up);
>  	} else {
>  		ret = early_init_dt_alloc_reserved_memory_arch(size, align,
>  							0, 0, nomap, &base);
>