linux-kernel - Re: [PATCH v7 1/3] ACPI/IORT: Fixup SMMUv3 resource size for Cavium ThunderX2 SMMUv3 model

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Message-ID: <20170608085857.GB8607@red-moon>
Date:   Thu, 8 Jun 2017 09:58:58 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Geetha sowjanya <gakula@...iumnetworks.com>
Cc:     will.deacon@....com, robin.murphy@....com, hanjun.guo@...aro.org,
        sudeep.holla@....com, iommu@...ts.linux-foundation.org,
        robert.moore@...el.com, lv.zheng@...el.com, rjw@...ysocki.net,
        jcm@...hat.com, linux-kernel@...r.kernel.org,
        robert.richter@...ium.com, catalin.marinas@....com,
        sgoutham@...ium.com, linux-arm-kernel@...ts.infradead.org,
        linux-acpi@...r.kernel.org, geethasowjanya.akula@...il.com,
        devel@...ica.org, linu.cherian@...ium.com,
        Charles.Garcia-Tobin@....com, robh@...nel.org,
        Geetha Sowjanya <geethasowjanya.akula@...ium.com>
Subject: Re: [PATCH v7 1/3] ACPI/IORT: Fixup SMMUv3 resource size for Cavium
 ThunderX2 SMMUv3 model

On Tue, May 30, 2017 at 05:33:39PM +0530, Geetha sowjanya wrote:
> From: Linu Cherian <linu.cherian@...ium.com>
> 
> Cavium ThunderX2 implementation doesn't support second page in SMMU
> register space. Hence, resource size is set as 64k for this model.
> 
> Signed-off-by: Linu Cherian <linu.cherian@...ium.com>
> Signed-off-by: Geetha Sowjanya <geethasowjanya.akula@...ium.com>
> ---
>  drivers/acpi/arm64/iort.c |   10 +++++++++-
>  1 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index c5fecf9..bba2b59 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -833,12 +833,20 @@ static void __init arm_smmu_v3_init_resources(struct resource *res,
>  {
>  	struct acpi_iort_smmu_v3 *smmu;
>  	int num_res = 0;
> +	unsigned long size = SZ_128K;
>  
>  	/* Retrieve SMMUv3 specific data */
>  	smmu = (struct acpi_iort_smmu_v3 *)node->node_data;
>  
> +	/*
> +	 * Override the size, for Cavium ThunderX2 implementation
> +	 * which doesn't support the page 1 SMMU register space.
> +	 */
> +	if (smmu->model == ACPI_IORT_SMMU_CAVIUM_CN99XX)
> +		size = SZ_64K;

Nit: add a function, say arm_smmu_v3_resource_size() with the logic
above that by default returns SZ_128K, I do not like this switch
in the middle of this function.

Lorenzo

> +
>  	res[num_res].start = smmu->base_address;
> -	res[num_res].end = smmu->base_address + SZ_128K - 1;
> +	res[num_res].end = smmu->base_address + size - 1;
>  	res[num_res].flags = IORESOURCE_MEM;
>  
>  	num_res++;
> -- 
> 1.7.1
>