linux-kernel - Re: [PATCH 3/4] spi: cadence-quadspi: Fix cqspi_setup

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Message-ID: <ea97b0b4-3467-4e18-9e8c-80b75e067f3d@ti.com>
Date: Fri, 5 Sep 2025 16:34:10 +0530
From: Santhosh Kumar K <s-k6@...com>
To: Pratyush Yadav <pratyush@...nel.org>
CC: <miquel.raynal@...tlin.com>, <broonie@...nel.org>, <vigneshr@...com>,
        <marex@...x.de>, <computersforpeace@...il.com>,
        <grmoore@...nsource.altera.com>, <theo.lebrun@...tlin.com>,
        <linux-spi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <praneeth@...com>, <p-mantena@...com>, <a-dutta@...com>,
        <u-kumar1@...com>, <s-k6@...com>
Subject: Re: [PATCH 3/4] spi: cadence-quadspi: Fix cqspi_setup_flash()

Hello,

On 04/09/25 20:11, Pratyush Yadav wrote:
> On Thu, Sep 04 2025, Santhosh Kumar K wrote:
> 
>> The 'max_cs' stores the largest chip select number. It should only
>> be updated when the current 'cs' is greater than existing 'max_cs'. So,
>> fix the condition accordingly.
>>
>> Fixes: 0f3841a5e115 ("spi: cadence-qspi: report correct number of chip-select")
>> Signed-off-by: Santhosh Kumar K <s-k6@...com>
>> ---
>>   drivers/spi/spi-cadence-quadspi.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
>> index 447a32a08a93..da3ec15abb3e 100644
>> --- a/drivers/spi/spi-cadence-quadspi.c
>> +++ b/drivers/spi/spi-cadence-quadspi.c
>> @@ -1722,7 +1722,7 @@ static const struct spi_controller_mem_caps cqspi_mem_caps = {
>>   
>>   static int cqspi_setup_flash(struct cqspi_st *cqspi)
>>   {
>> -	unsigned int max_cs = cqspi->num_chipselect - 1;
>> +	unsigned int max_cs = 0;
>>   	struct platform_device *pdev = cqspi->pdev;
>>   	struct device *dev = &pdev->dev;
>>   	struct cqspi_flash_pdata *f_pdata;
>> @@ -1740,7 +1740,7 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi)
>>   		if (cs >= cqspi->num_chipselect) {
>>   			dev_err(dev, "Chip select %d out of range.\n", cs);
>>   			return -EINVAL;
>> -		} else if (cs < max_cs) {
>> +		} else if (cs > max_cs) {
> 
> Makes sense. Out of curiosity, are you using multiple CS in a real use
> case or is this only theoretical?

Real use case,  Pratyush - we have both OSPI NOR and QSPI NAND in our 
new AM62Lx EVM - CS0 and CS3 respectively.

> 
> Also nit: this could be simplified to:
> 
> 		if (cs >= cqspi->num_chipselect) {
> 			dev_err(dev, "Chip select %d out of range.\n", cs);
> 			return -EINVAL;
> 		}
> 
> 		max_cs = max_t(unsigned int, cs, max_cs);
> 
> but I think it is fine either way.

Yeah, this one's simpler, I'll go with this. Thanks!

Regards,
Santhosh.

> 
> Reviewed-by: Pratyush Yadav <pratyush@...nel.org>
> 
>>   			max_cs = cs;
>>   		}
>