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

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Message-ID: <c627314d-fdf6-7e69-7c54-03a513f563fc@microchip.com>
Date:   Mon, 21 Jan 2019 09:37:24 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <purna.chandra.mandal@...el.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

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?

> 
> 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().

>  	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;



>  		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);

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;
>  }
>