linux-kernel - Re: [LINUX PATCH 2/3] spi: spi-mem: call spi_mem_default_supports

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Date:   Fri, 29 Mar 2019 13:50:26 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Boris Brezillon <boris.brezillon@...labora.com>,
        Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
CC:     "broonie@...nel.org" <broonie@...nel.org>,
        "bbrezillon@...nel.org" <bbrezillon@...nel.org>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "richard@....at" <richard@....at>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "michal.simek@...inx.com" <michal.simek@...inx.com>,
        "nagasuresh12@...il.com" <nagasuresh12@...il.com>
Subject: Re: [LINUX PATCH 2/3] spi: spi-mem: call
 spi_mem_default_supports_op() first

Hi Boris,

On 29/03/19 1:25 AM, Boris Brezillon wrote:
> On Thu, 28 Mar 2019 16:46:24 +0530
> Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com> wrote:
> 
>> Call spi_mem_default_supports_op() first, before calling controller
>> specific ctlr->supports_op().
>> With this, controller drivers can drop checking the buswidths again.
> 
> No, this was done on purpose, in case the controller does not want the
> default check to be applied (say it does not need bus-width props to
> be defined and has another way to check if a device can be accessed in
> dual, quad or octal mode).

Sorry, I don't understand here.
Based on capabilities declared in spi_device->mode, m25p80 driver will
claim appropriate  SNOR_HWCAPS_*.  SPI NOR layer chooses opcodes based
on that for which m25p80 layer populates buswidths.

So, I don't really expect any mismatch in spi_mem_default_supports_op()
in the case you mentioned. Or did I miss something? Maybe something SPI
NAND specific?

Regards
Vignesh

> Just call spi_mem_default_supports_op() from your driver
> ->supports_op() hook if needed.
> 
>>
>> Suggested-by: Vignesh Raghavendra <vigneshr@...com>
>> Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
>> ---
>> Details can be found at https://lkml.org/lkml/2019/3/1/183
>> ---
>>  drivers/spi/spi-mem.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
>> index 5217a56..56aa158 100644
>> --- a/drivers/spi/spi-mem.c
>> +++ b/drivers/spi/spi-mem.c
>> @@ -189,11 +189,14 @@ static bool spi_mem_internal_supports_op(struct spi_mem *mem,
>>  					 const struct spi_mem_op *op)
>>  {
>>  	struct spi_controller *ctlr = mem->spi->controller;
>> +	bool ret;
>> +
>> +	ret = spi_mem_default_supports_op(mem, op);
>>  
>>  	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
>> -		return ctlr->mem_ops->supports_op(mem, op);
>> +		ret =  ctlr->mem_ops->supports_op(mem, op);
>>  
>> -	return spi_mem_default_supports_op(mem, op);
>> +	return ret;
>>  }
>>  
>>  /**
>