linux-kernel - Re: [PATCH v2 2/2] spi: cadence-quadspi: Fix check condition for DTR ops

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Message-ID: <c6bb03ff-1192-5276-4034-4a021e4f6923@ti.com>
Date:   Wed, 21 Jul 2021 20:23:30 +0530
From:   "Nandan, Apurva" <a-nandan@...com>
To:     Mark Brown <broonie@...nel.org>, <linux-spi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Pratyush Yadav <p.yadav@...com>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH v2 2/2] spi: cadence-quadspi: Fix check condition for DTR
 ops



On 17-Jul-21 4:55 AM, Apurva Nandan wrote:
> buswidth and dtr fields in spi_mem_op are only valid when the
> corresponding spi_mem_op phase has a non-zero length. For example,
> SPI NAND core doesn't set buswidth when using SPI_MEM_OP_NO_ADDR
> phase.
> 
> Fix the dtr checks in set_protocol() and suppports_mem_op() to
> ignore empty spi_mem_op phases, as checking for dtr field in
> empty phase will result in false negatives.
> 
> Signed-off-by: Apurva Nandan <a-nandan@...com>
> ---
>  drivers/spi/spi-cadence-quadspi.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
> index a2de23516553..1cec1c179a94 100644
> --- a/drivers/spi/spi-cadence-quadspi.c
> +++ b/drivers/spi/spi-cadence-quadspi.c
> @@ -325,7 +325,15 @@ static int cqspi_set_protocol(struct cqspi_flash_pdata *f_pdata,
>  	f_pdata->inst_width = CQSPI_INST_TYPE_SINGLE;
>  	f_pdata->addr_width = CQSPI_INST_TYPE_SINGLE;
>  	f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
> -	f_pdata->dtr = op->data.dtr && op->cmd.dtr && op->addr.dtr;
> +
> +	/*
> +	 * For an op to be DTR, cmd phase along with every other non-empty
> +	 * phase should have dtr field set to 1. If an op phase has zero
> +	 * nbytes, ignore its dtr field; otherwise, check its dtr field.
> +	 */
> +	f_pdata->dtr = op->cmd.dtr &&
> +		       (!op->addr.nbytes || op->addr.dtr) &&
> +		       (!op->data.nbytes || op->data.dtr);
>  
>  	switch (op->data.buswidth) {
>  	case 0:
> @@ -1228,8 +1236,15 @@ static bool cqspi_supports_mem_op(struct spi_mem *mem,
>  {
>  	bool all_true, all_false;
>  
> -	all_true = op->cmd.dtr && op->addr.dtr && op->dummy.dtr &&
> -		   op->data.dtr;
> +	/*
> +	 * op->dummy.dtr is required for converting nbytes into ncycles.
> +	 * Also, don't check the dtr field of the op phase having zero nbytes.
> +	 */
> +	all_true = op->cmd.dtr &&
> +		   (!op->addr.nbytes || op->addr.dtr) &&
> +		   (!op->dummy.nbytes || op->dummy.dtr) &&
> +		   (!op->data.nbytes || op->data.dtr);
> +
>  	all_false = !op->cmd.dtr && !op->addr.dtr && !op->dummy.dtr &&
>  		    !op->data.dtr;
>  
> 

Hi Mark,

Could you please have a look, I fixed the comments as you suggested.

Thanks and regards,
Apurva Nandan