Re: [PATCH v4 1/3] spi: spi-mem: add automatic poll status functions

[Patrice CHOTARD]

On 5/18/21 4:12 PM, Boris Brezillon wrote:
> On Tue, 18 May 2021 15:43:30 +0200
> <patrice.chotard@xxxxxxxxxxx> wrote:
> 
>> From: Patrice Chotard <patrice.chotard@xxxxxxxxxxx>
>>
>> With STM32 QSPI, it is possible to poll the status register of the device.
>> This could be done to offload the CPU during an operation (erase or
>> program a SPI NAND for example).
>>
>> spi_mem_poll_status API has been added to handle this feature.
>> This new function take care of the offload/non-offload cases.
>>
>> For the non-offload case, use read_poll_timeout() to poll the status in
>> order to release CPU during this phase.
>> For example, previously, when erasing large area, in non-offload case,
>> CPU load can reach ~50%, now it decrease to ~35%.
>>
>> Signed-off-by: Patrice Chotard <patrice.chotard@xxxxxxxxxxx>
>> Signed-off-by: Christophe Kerello <christophe.kerello@xxxxxxxxxxx>
>> ---
>> Changes in v4:
>>   - Remove init_completion() from spi_mem_probe() added in v2.
>>   - Add missing static for spi_mem_read_status().
>>   - Check if operation in spi_mem_poll_status() is a READ.
>>
>> Changes in v3:
>>   - Add spi_mem_read_status() which allows to read 8 or 16 bits status.
>>   - Add initial_delay_us and polling_delay_us parameters to spi_mem_poll_status()
>>     and also to poll_status() callback.
>>   - Move spi_mem_supports_op() in SW-based polling case.
>>   - Add delay before invoking read_poll_timeout().
>>   - Remove the reinit/wait_for_completion() added in v2.
>>
>> Changes in v2:
>>   - Indicates the spi_mem_poll_status() timeout unit
>>   - Use 2-byte wide status register
>>   - Add spi_mem_supports_op() call in spi_mem_poll_status()
>>   - Add completion management in spi_mem_poll_status()
>>   - Add offload/non-offload case management in spi_mem_poll_status()
>>   - Optimize the non-offload case by using read_poll_timeout()
>>
>>  drivers/spi/spi-mem.c       | 85 +++++++++++++++++++++++++++++++++++++
>>  include/linux/spi/spi-mem.h | 14 ++++++
>>  2 files changed, 99 insertions(+)
>>
>> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
>> index 1513553e4080..97c7a83686c7 100644
>> --- a/drivers/spi/spi-mem.c
>> +++ b/drivers/spi/spi-mem.c
>> @@ -6,6 +6,7 @@
>>   * Author: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
>>   */
>>  #include <linux/dmaengine.h>
>> +#include <linux/iopoll.h>
>>  #include <linux/pm_runtime.h>
>>  #include <linux/spi/spi.h>
>>  #include <linux/spi/spi-mem.h>
>> @@ -743,6 +744,90 @@ static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv)
>>  	return container_of(drv, struct spi_mem_driver, spidrv.driver);
>>  }
>>  
>> +static int spi_mem_read_status(struct spi_mem *mem,
>> +			       const struct spi_mem_op *op,
>> +			       u16 *status)
>> +{
>> +	const u8 *bytes = (u8 *)op->data.buf.in;
>> +	int ret;
>> +
>> +	ret = spi_mem_exec_op(mem, op);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (op->data.nbytes > 1)
>> +		*status = ((u16)bytes[0] << 8) | bytes[1];
>> +	else
>> +		*status = bytes[0];
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * spi_mem_poll_status() - Poll memory device status
>> + * @mem: SPI memory device
>> + * @op: the memory operation to execute
>> + * @mask: status bitmask to ckeck
>> + * @match: (status & mask) expected value
>> + * @initial_delay_us: delay in us before starting to poll
>> + * @polling_delay_us: time to sleep between reads in us
>> + * @timeout_ms: timeout in milliseconds
>> + *
>> + * This function send a polling status request to the controller driver
> 
> "
> This function polls a status register and returns when
> (status & mask) == match or when the timeout has expired.
> "

Ok i will update spi_mem_poll_status description

> 
>> + *
>> + * Return: 0 in case of success, -ETIMEDOUT in case of error,
>> + *         -EOPNOTSUPP if not supported.
>> + */
>> +int spi_mem_poll_status(struct spi_mem *mem,
>> +			const struct spi_mem_op *op,
>> +			u16 mask, u16 match,
>> +			unsigned long initial_delay_us,
>> +			unsigned long polling_delay_us,
>> +			u16 timeout_ms)
>> +{
>> +	struct spi_controller *ctlr = mem->spi->controller;
>> +	int ret = -EOPNOTSUPP;
>> +	int read_status_ret;
>> +	u16 status;
>> +
>> +	if (op->data.nbytes < 1 || op->data.nbytes > 2 ||
>> +	    op->data.dir != SPI_MEM_DATA_IN)
>> +		return (-EINVAL);
> 
> s/return (-EINVAL);/return -EINVAL;/

Ok

> 
> 
> [...]
> 
>>  /**
>> @@ -369,6 +376,13 @@ devm_spi_mem_dirmap_create(struct device *dev, struct spi_mem *mem,
>>  void devm_spi_mem_dirmap_destroy(struct device *dev,
>>  				 struct spi_mem_dirmap_desc *desc);
>>  
>> +int spi_mem_poll_status(struct spi_mem *mem,
>> +			const struct spi_mem_op *op,
>> +			u16 mask, u16 match,
>> +			unsigned long initial_delay_us,
>> +			unsigned long polling_delay_us,
>> +			u16 timeout);
> 
> s/timeout/timeout_ms/.

Ok 

> 
> With those minor things fixed
> 
> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>

Thanks
Patrice


> 
>> +
>>  int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv,
>>  				       struct module *owner);
>>  
>