linux-kernel - Re: [PATCH v2 3/4] remoteproc: k3-r5: Initialize TCM memories for ECC

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Message-ID: <20200709192923.GB948668@xps15>
Date:   Thu, 9 Jul 2020 13:29:23 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Suman Anna <s-anna@...com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lokesh Vutla <lokeshvutla@...com>,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] remoteproc: k3-r5: Initialize TCM memories for ECC

On Mon, Jun 29, 2020 at 09:49:21PM -0500, Suman Anna wrote:
> The R5F processors on K3 SoCs all have two TCMs (ATCM and BTCM) that
> support 32-bit ECC. The TCMs are typically loaded with some boot-up
> code to initialize the R5 MPUs to further execute code out of DDR.
> The ECC for the TCMs is enabled by default on K3 SoCs due to internal
> default tie-off values, but the TCM memories are not initialized on
> device power up. Any read access without the corresponding TCM memory
> location initialized will generate an ECC error, and any such access
> from a A72 or A53 core will trigger a SError.
> 
> So, zero initialize both the TCM memories before loading any firmware
> onto a R5F in remoteproc mode. Any R5F booted from U-Boot/SPL would
> require a similar initialization in the bootloader. Note that both
> the TCMs are initialized unconditionally as the TCM enable config bits
> only manage the access and visibility from R5.
> 
> Signed-off-by: Suman Anna <s-anna@...com>
> ---
> v2:
>  - Fixed the logic of initializing TCMs even when the resets deassertion
>    failed
>  - Dropped the confusing last sentence from the 2nd paragraph of the
>    patch description
>  - Revised the patch title to move away from remoteproc/k3-r5
>  - Dropped Mathieu's Acked-by because of the changes
> v1: https://patchwork.kernel.org/patch/11456371/
> 
>  drivers/remoteproc/ti_k3_r5_remoteproc.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> index c4f99e59dc2f..aca0eaf42a38 100644
> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> @@ -363,11 +363,24 @@ static int k3_r5_rproc_prepare(struct rproc *rproc)
>  
>  	ret = (cluster->mode == CLUSTER_MODE_LOCKSTEP) ?
>  		k3_r5_lockstep_release(cluster) : k3_r5_split_release(core);
> -	if (ret)
> +	if (ret) {
>  		dev_err(dev, "unable to enable cores for TCM loading, ret = %d\n",
>  			ret);
> +		return ret;
> +	}
>  
> -	return ret;
> +	/*
> +	 * Zero out both TCMs unconditionally (access from v8 Arm core is not
> +	 * affected by ATCM & BTCM enable configuration values) so that ECC
> +	 * can be effective on all TCM addresses.
> +	 */
> +	dev_dbg(dev, "zeroing out ATCM memory\n");
> +	memset(core->mem[0].cpu_addr, 0x00, core->mem[0].size);
> +
> +	dev_dbg(dev, "zeroing out BTCM memory\n");
> +	memset(core->mem[1].cpu_addr, 0x00, core->mem[1].size);
> +
> +	return 0;

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

>  }
>  
>  /*
> -- 
> 2.26.0
>