linux-kernel - Re: [PATCH] remoteproc: mediatek: Zero out only remaining bytes of IPI buffer

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Date: Mon, 20 May 2024 20:31:35 +0530
From: Mukesh Ojha <quic_mojha@...cinc.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
        <mathieu.poirier@...aro.org>
CC: <andersson@...nel.org>, <matthias.bgg@...il.com>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <kernel@...labora.com>
Subject: Re: [PATCH] remoteproc: mediatek: Zero out only remaining bytes of
 IPI buffer



On 5/20/2024 4:57 PM, AngeloGioacchino Del Regno wrote:
> In scp_ipi_handler(), instead of zeroing out the entire shared
> buffer, which may be as large as 600 bytes, overwrite it with the
> received data, then zero out only the remaining bytes.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>   drivers/remoteproc/mtk_scp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
> index e5214d43181e..dc70cf7db44d 100644
> --- a/drivers/remoteproc/mtk_scp.c
> +++ b/drivers/remoteproc/mtk_scp.c
> @@ -117,8 +117,8 @@ static void scp_ipi_handler(struct mtk_scp *scp)
>   		return;
>   	}
>   
> -	memset(scp->share_buf, 0, scp_sizes->ipi_share_buffer_size);
>   	memcpy_fromio(scp->share_buf, &rcv_obj->share_buf, len);
> +	memset(&scp->share_buf[len], 0, scp_sizes->ipi_share_buffer_size - len);

Although, it does not make any difference apart from a write of len 
bytes, still a good improvement to do ..

Acked-by: Mukesh Ojha <quic_mojha@...cinc.com>

-Mukesh

>   	handler(scp->share_buf, len, ipi_desc[id].priv);
>   	scp_ipi_unlock(scp, id);
>