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Subject: Re: [PATCH] mtd: spi-nor: cadence-quadspi: write upto 8-bytes data in
 STIG mode
To:     "Tudor.Ambarus@microchip.com" <Tudor.Ambarus@microchip.com>,
        "purna.chandra.mandal@intel.com" <purna.chandra.mandal@intel.com>,
        "f.blogs@napier.co.nz" <f.blogs@napier.co.nz>,
        "boris.brezillon@bootlin.com" <boris.brezillon@bootlin.com>,
        "richard@nod.at" <richard@nod.at>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "marek.vasut@gmail.com" <marek.vasut@gmail.com>,
        "computersforpeace@gmail.com" <computersforpeace@gmail.com>,
        "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
        "dwmw2@infradead.org" <dwmw2@infradead.org>
References: <20190128050229.44965-1-purna.chandra.mandal@intel.com>
 <82eafaf8-803e-36a9-49ca-83d84c55537a@microchip.com>
From:   Vignesh R <vigneshr@ti.com>
Message-ID: <7655324a-9cd2-7ffe-56bb-83c44740265c@ti.com>
Date:   Mon, 4 Feb 2019 19:07:39 +0530
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Hi,

On 03/02/19 5:50 PM, Tudor.Ambarus@microchip.com wrote:
> + Vignesh
> 

Thanks for looping in.

> On 01/28/2019 07:02 AM, Purna Chandra Mandal wrote:
>> cadence-quadspi controller allows upto eight bytes of data to
>> be written in software Triggered Instruction generator (STIG) mode
>> of operation. Lower 4 bytes are written through writedatalower and
>> upper 4 bytes by writedataupper register.
>>
>> This patch allows all the 8 bytes to be written.
>>

Code as such looks fine. But, how was this tested? How can I trigger
this new code path with current linux-next? AFAICS, STIG mode write is
used to in nor->write_reg() path, and I dont see any nor->write_reg()
call with >4bytes len.

>> Signed-off-by: Purna Chandra Mandal <purna.chandra.mandal@intel.com>
> 
> Looks good for me:
> Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> 
> Vignesh, can we have your R-b or T-b tag?
> 
> Cheers,
> ta
> 
>> ---
>>
>>  drivers/mtd/spi-nor/cadence-quadspi.c | 15 ++++++++++++---
>>  1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
>> index 04cedd3a2bf6..7f78f9409ddd 100644
>> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
>> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
>> @@ -418,9 +418,10 @@ static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
>>  	void __iomem *reg_base = cqspi->iobase;
>>  	unsigned int reg;
>>  	unsigned int data;
>> +	u32 write_len;
>>  	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);
>> @@ -433,10 +434,18 @@ static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
>>  		reg |= ((n_tx - 1) & CQSPI_REG_CMDCTRL_WR_BYTES_MASK)
>>  			<< CQSPI_REG_CMDCTRL_WR_BYTES_LSB;
>>  		data = 0;
>> -		memcpy(&data, txbuf, n_tx);
>> +		write_len = (n_tx > 4) ? 4 : n_tx;
>> +		memcpy(&data, txbuf, write_len);
>> +		txbuf += write_len;
>>  		writel(data, reg_base + CQSPI_REG_CMDWRITEDATALOWER);
>> -	}
>>  
>> +		if (n_tx > 4) {
>> +			data = 0;
>> +			write_len = n_tx - 4;
>> +			memcpy(&data, txbuf, write_len);
>> +			writel(data, reg_base + CQSPI_REG_CMDWRITEDATAUPPER);
>> +		}
>> +	}
>>  	ret = cqspi_exec_flash_cmd(cqspi, reg);
>>  	return ret;
>>  }
>>

-- 
Regards
Vignesh