linux-kernel - Re: [PATCH] fpga: altera-cvp: Truncated bitstream error support

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Date:   Wed, 18 May 2022 22:54:40 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     tien.sung.ang@...el.com, mdf@...nel.org, hao.wu@...el.com,
        yilun.xu@...el.com, trix@...hat.com
Cc:     linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fpga: altera-cvp: Truncated bitstream error support

Le 18/05/2022 à 08:48, tien.sung.ang@...el.com a écrit :
> From: Ang Tien Sung <tien.sung.ang@...el.com>
> 
> To support the error handling of a truncated bitstream sent.
> The current AIB CvP firmware is not capable of handling a
> data stream smaller than 4096bytes. The firmware's limitation
> causes a hung-up as it's DMA engine waits forever for the
> completion of the instructed 4096bytes.
> To resolve this design limitation, both firmware and CvP
> driver made several changes. At the CvP driver, we just
> have to ensure that anything lesser than 4096bytes are
> padded with extra bytes. The CvP will then, initiate the
> tear-down by clearing the START_XFER and CVP_CONFIG bits.
> We should also check for CVP_ERROR during the CvP completion.
> A send_buf which is always 4096bytes is used to copy the
> data during every transaction.
> 
> Signed-off-by: Ang Tien Sung <tien.sung.ang@...el.com>
> ---
>   drivers/fpga/altera-cvp.c | 24 +++++++++++++++++++-----
>   1 file changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index 4ffb9da537d8..80edcfb5e5fc 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -81,6 +81,7 @@ struct altera_cvp_conf {
>   	u8			numclks;
>   	u32			sent_packets;
>   	u32			vsec_offset;
> +	u8			*send_buf;
>   	const struct cvp_priv	*priv;
>   };
>   
> @@ -453,7 +454,11 @@ static int altera_cvp_write(struct fpga_manager *mgr, const char *buf,
>   		}
>   
>   		len = min(conf->priv->block_size, remaining);
> -		altera_cvp_send_block(conf, data, len);
> +		/* Copy the requested host data into the transmit buffer */
> +
> +		memcpy(conf->send_buf, data, len);
> +		altera_cvp_send_block(conf, (const u32 *)conf->send_buf,
> +		conf->priv->block_size);

Nitpicking: this should be aligned with 'conf'.

CJ

>   		data += len / sizeof(u32);
>   		done += len;
>   		remaining -= len;

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