linux-kernel - Re: [PATCH] mtd: spi-nor: cadence-quadspi: write upto 8-bytes data in STIG mode

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Message-ID: <76066a83-1cd2-5baf-1930-c290f66e73ba@intel.com>
Date:   Mon, 28 Jan 2019 10:27:20 +0530
From:   "Mandal, Purna Chandra" <purna.chandra.mandal@...el.com>
To:     Tudor.Ambarus@...rochip.com, f.blogs@...ier.co.nz,
        boris.brezillon@...tlin.com
Cc:     linux-kernel@...r.kernel.org, marek.vasut@...il.com,
        computersforpeace@...il.com, richard@....at,
        linux-mtd@...ts.infradead.org, dwmw2@...radead.org, vigneshr@...com
Subject: Re: [PATCH] mtd: spi-nor: cadence-quadspi: write upto 8-bytes data in
 STIG mode


On 21-Jan-19 3:07 PM, Tudor.Ambarus@...rochip.com wrote:
> Hi, Purna,
> 
> On 12/14/2018 04:15 AM, Purna Chandra Mandal wrote:
>> cadence-quadspi controller allows upto eight bytes of data to be transferred
>> in software Triggered Instruction generator (STIG) mode of operation. Lower
>> 4 bytes are written through writedatalower and upper 4 bytes by
>> writedataupper register.
> 
> Is this supported by all versions of the IP?
> 
Yes, it is supported on all versions of IP.
>>
>> This patch allows all the 8 bytes to be written.
>>
>> Signed-off-by: Purna Chandra Mandal <purna.chandra.mandal@...el.com>
>> ---
>>
>>   drivers/mtd/spi-nor/cadence-quadspi.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
>> index 04cedd3a2bf6..990934387fea 100644
>> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
>> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
>> @@ -420,7 +420,7 @@ static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
>>   	unsigned int data;
> 
> I know that this is not your change, but data should be u32 and not unsigned
> int. reg too ... probably one should submit a patch to change this, I see that
> the same error is done in cqspi_command_read().
ack. will be done in separate patch.
> 
>>   	int ret;
>>   
>> -	if (n_tx > 4 || (n_tx && !txbuf)) {
>> +	if (n_tx > CQSPI_STIG_DATA_LEN_MAX || (n_tx && !txbuf)) {
>>   		dev_err(nor->dev,
>>   			"Invalid input argument, cmdlen %d txbuf 0x%p\n",
>>   			n_tx, txbuf);
>> @@ -435,8 +435,13 @@ static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
>>   		data = 0;>  		memcpy(&data, txbuf, n_tx);
> 
> You should limit what is copied in data, similar to what is done in
> cqspi_command_read():
> 
> write_len = (n_tx > 4) ? 4 : n_tx;
> memcpy(&data, txbuf, write_len);
> txbuf += write_len;
ack.
> 
> 
> 
>>   		writel(data, reg_base + CQSPI_REG_CMDWRITEDATALOWER);
>> -	}
>>   
>> +		if (n_tx > 4) {
>> +			data = 0;
> and then:
> write_len = n_tx - 4;
> memcpy(&data, txbuf, write_len);
> 
ack.
> Cheers,
> ta
> 
>> +			memcpy(&data, txbuf + 4, n_tx - 4);
>> +			writel(data, reg_base + CQSPI_REG_CMDWRITEDATAUPPER);
>> +		}
>> +	}
>>   	ret = cqspi_exec_flash_cmd(cqspi, reg);
>>   	return ret;
>>   }
>>