linux-kernel - Re: [PATCH 01/11] spi: spi-mem: Extend the SPI mem interface to set a custom memory name

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Date:   Wed, 30 May 2018 17:12:18 +0200
From:   Frieder Schrempf <frieder.schrempf@...eet.de>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     linux-mtd@...ts.infradead.org, linux-spi@...r.kernel.org,
        dwmw2@...radead.org, computersforpeace@...il.com,
        marek.vasut@...il.com, richard@....at, miquel.raynal@...tlin.com,
        broonie@...nel.org, david.wolfe@....com, fabio.estevam@....com,
        prabhakar.kushwaha@....com, yogeshnarayan.gaur@....com,
        han.xu@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/11] spi: spi-mem: Extend the SPI mem interface to set a
 custom memory name

Hi Boris,

On 30.05.2018 16:32, Boris Brezillon wrote:
> Hi Frieder,
> 
> On Wed, 30 May 2018 15:14:30 +0200
> Frieder Schrempf <frieder.schrempf@...eet.de> wrote:
> 
>> When porting (Q)SPI controller drivers from the MTD layer to the SPI
>> layer, the naming scheme for the memory devices changes. To be able
>> to keep compatibility with the old drivers naming scheme, a function
>> is added to the SPI mem interface to let controller drivers set a
>> custom name for the memory.
>>
>> Example for the FSL QSPI driver:
>>
>> Name with the old driver: 21e0000.qspi,
>> or with multiple devices: 21e0000.qspi-0, 21e0000.qspi-1, ...
>>
>> Name with the new driver without spi_mem_get_name: spi4.0
>>
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@...eet.de>
>> ---
>>   drivers/spi/spi-mem.c       | 25 +++++++++++++++++++++++++
>>   include/linux/spi/spi-mem.h |  3 +++
>>   2 files changed, 28 insertions(+)
>>
>> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
>> index 990770d..5e9af47 100644
>> --- a/drivers/spi/spi-mem.c
>> +++ b/drivers/spi/spi-mem.c
>> @@ -311,6 +311,31 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>>   EXPORT_SYMBOL_GPL(spi_mem_exec_op);
>>   
>>   /**
>> + * spi_mem_get_name() - Let drivers using the SPI mem interface specify a
>> + *			custom name for the memory to avoid compatibility
>> + *			issues with ported drivers.
>> + * @mem: the SPI memory
>> + *
>> + * When porting (Q)SPI controller drivers from the MTD layer to the SPI
>> + * layer, the naming scheme for the memory devices changes. To be able to
>> + * keep compatibility with the old drivers naming scheme, this function can
>> + * be used to get a custom name from the controller driver.
>> + * If no custom name is available, the name of the SPI device is returned.
>> + *
>> + * Return: a char array that contains the name for the flash memory
>> + */
>> +const char *spi_mem_get_name(struct spi_mem *mem)
>> +{
>> +	struct spi_controller *ctlr = mem->spi->controller;
>> +
>> +	if (ctlr->mem_ops && ctlr->mem_ops->get_name)
>> +		return ctlr->mem_ops->get_name(mem);
> 
> Looks like your implementation of ->get_name() in the fsl driver is
> allocating a new string each time it's called. I guess other
> implementations might be forced to do the same, so maybe it's better to
> add a ->name field to struct spi_mem and only call ->get_name() once
> when the device is probed. Then spi_mem_get_name() can just be
> implemented like this:
> 
> const char *spi_mem_get_name(struct spi_mem *mem)
> {
> 	return mem->name;
> }

Sounds like a good proposal. I will change that.

Thanks,

Frieder

> 
> Regards,
> 
> Boris
> 
>> +
>> +	return dev_name(&mem->spi->dev);
>> +}
>> +EXPORT_SYMBOL_GPL(spi_mem_get_name);
>> +
>> +/**
>>    * spi_mem_adjust_op_size() - Adjust the data size of a SPI mem operation to
>>    *			      match controller limitations
>>    * @mem: the SPI memory
>> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
>> index 4fa34a2..f1912d3 100644
>> --- a/include/linux/spi/spi-mem.h
>> +++ b/include/linux/spi/spi-mem.h
>> @@ -178,6 +178,7 @@ struct spi_controller_mem_ops {
>>   			    const struct spi_mem_op *op);
>>   	int (*exec_op)(struct spi_mem *mem,
>>   		       const struct spi_mem_op *op);
>> +	const char *(*get_name)(struct spi_mem *mem);
>>   };
>>   
>>   /**
>> @@ -236,6 +237,8 @@ bool spi_mem_supports_op(struct spi_mem *mem,
>>   int spi_mem_exec_op(struct spi_mem *mem,
>>   		    const struct spi_mem_op *op);
>>   
>> +const char *spi_mem_get_name(struct spi_mem *mem);
>> +
>>   int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv,
>>   				       struct module *owner);
>>   
>