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

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Message-ID: <81045d02-7020-f6e1-f1d3-75bbeccd3dde@linux.intel.com>
Date:   Mon, 15 Jul 2019 12:40:56 -0500
From:   Thor Thayer <thor.thayer@...ux.intel.com>
To:     Moritz Fischer <mdf@...nel.org>
Cc:     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.

On 7/14/19 1:46 PM, Moritz Fischer wrote:
> 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.

OK. Thanks.

>> +{
>> +	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.

OK. I'm new to the reverse xmas-tree but if I read [0] correctly, it 
isn't the size of the variable that is important but the length of the 
declaration.

>> +
>> +	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.

OK.

>>   	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?

No, this maintains the previous big endian byte handling for 
Cyclone5/Arria10. The Stratix10 bitstream is generated in 4KB chunks.

>>   	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
> 

I wasn't sure if you preferred this as a separate patch or squashed into 
patch #3. Having a separate patch makes the migration a little clearer.

Thanks for reviewing!

[0] https://www.spinics.net/lists/netdev/msg402833.html