linux-kernel - Re: [PATCH 2/3] fpga: altera-cvp: Preparation for V2 parts.

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Date:   Sun, 14 Jul 2019 11:46:17 -0700
From:   Moritz Fischer <mdf@...nel.org>
To:     thor.thayer@...ux.intel.com
Cc:     mdf@...nel.org, richard.gong@...el.com, agust@...x.de,
        linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] fpga: altera-cvp: Preparation for V2 parts.

Hi Thor,

On Thu, Jul 11, 2019 at 03:32:49PM -0500, thor.thayer@...ux.intel.com wrote:
> From: Thor Thayer <thor.thayer@...ux.intel.com>
> 
> In preparation for adding newer V2 parts that use a FIFO,
> reorganize altera_cvp_chk_error() and change the write
> function to block based.
> V2 parts have a block size matching the FIFO while older
> V1 parts write a 32 bit word at a time.
> 
> Signed-off-by: Thor Thayer <thor.thayer@...ux.intel.com>
> ---
>  drivers/fpga/altera-cvp.c | 72 ++++++++++++++++++++++++++++++-----------------
>  1 file changed, 46 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index 04f2b2a072a7..59835f6f9b2d 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -140,6 +140,41 @@ static int altera_cvp_wait_status(struct altera_cvp_conf *conf, u32 status_mask,
>  	return -ETIMEDOUT;
>  }
>  
> +static inline int altera_cvp_chk_error(struct fpga_manager *mgr, size_t bytes)

Please drop the inline here.
> +{
> +	struct altera_cvp_conf *conf = mgr->priv;
> +	u32 val;
> +
> +	/* STEP 10 (optional) - check CVP_CONFIG_ERROR flag */
> +	altera_read_config_dword(conf, VSE_CVP_STATUS, &val);
> +	if (val & VSE_CVP_STATUS_CFG_ERR) {
> +		dev_err(&mgr->dev, "CVP_CONFIG_ERROR after %zu bytes!\n",
> +			bytes);
> +		return -EPROTO;
> +	}
> +	return 0;
> +}
> +
> +static int altera_cvp_send_block(struct altera_cvp_conf *conf,
> +				 const u32 *data, size_t len)
> +{
> +	int i, remainder;
> +	u32 mask, words = len / sizeof(u32);
Reverse xmas-tree, please.
> +
> +	for (i = 0; i < words; i++)
> +		conf->write_data(conf, *data++);
> +
> +	/* write up to 3 trailing bytes, if any */
> +	remainder = len % sizeof(u32);
> +	if (remainder) {
> +		mask = BIT(remainder * 8) - 1;
> +		if (mask)
> +			conf->write_data(conf, *data & mask);
> +	}
> +
> +	return 0;
> +}
> +
>  static int altera_cvp_teardown(struct fpga_manager *mgr,
>  			       struct fpga_image_info *info)
>  {
> @@ -262,39 +297,29 @@ static int altera_cvp_write_init(struct fpga_manager *mgr,
>  	return 0;
>  }
>  
> -static inline int altera_cvp_chk_error(struct fpga_manager *mgr, size_t bytes)
> -{
> -	struct altera_cvp_conf *conf = mgr->priv;
> -	u32 val;
> -
> -	/* STEP 10 (optional) - check CVP_CONFIG_ERROR flag */
> -	altera_read_config_dword(conf, VSE_CVP_STATUS, &val);
> -	if (val & VSE_CVP_STATUS_CFG_ERR) {
> -		dev_err(&mgr->dev, "CVP_CONFIG_ERROR after %zu bytes!\n",
> -			bytes);
> -		return -EPROTO;
> -	}
> -	return 0;
> -}
> -
>  static int altera_cvp_write(struct fpga_manager *mgr, const char *buf,
>  			    size_t count)
>  {
>  	struct altera_cvp_conf *conf = mgr->priv;
>  	const u32 *data;
> -	size_t done, remaining;
> +	size_t done, remaining, len;

Reverse xmas-tree please.
>  	int status = 0;
> -	u32 mask;
>  
>  	/* STEP 9 - write 32-bit data from RBF file to CVP data register */
>  	data = (u32 *)buf;

Are there endianness concerns with this?
>  	remaining = count;
>  	done = 0;
>  
> -	while (remaining >= 4) {
> -		conf->write_data(conf, *data++);
> -		done += 4;
> -		remaining -= 4;
> +	while (remaining) {
> +		if (remaining >= sizeof(u32))
> +			len = sizeof(u32);
> +		else
> +			len = remaining;
> +
> +		altera_cvp_send_block(conf, data, len);
> +		data++;
> +		done += len;
> +		remaining -= len;
>  
>  		/*
>  		 * STEP 10 (optional) and STEP 11
> @@ -312,11 +337,6 @@ static int altera_cvp_write(struct fpga_manager *mgr, const char *buf,
>  		}
>  	}
>  
> -	/* write up to 3 trailing bytes, if any */
> -	mask = BIT(remaining * 8) - 1;
> -	if (mask)
> -		conf->write_data(conf, *data & mask);
> -
>  	if (altera_cvp_chkcfg)
>  		status = altera_cvp_chk_error(mgr, count);
>  
> -- 
> 2.7.4
> 

Thanks,
Moritz