linux-kernel - Re: [PATCH v2 2/2] spi: stm32-ospi: Make usage of reset_control

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Message-ID: <721ec8c6-ceb5-4e6c-91f6-2e234f12ff2b@foss.st.com>
Date: Wed, 7 May 2025 18:04:32 +0200
From: Patrice CHOTARD <patrice.chotard@...s.st.com>
To: Philipp Zabel <p.zabel@...gutronix.de>, Mark Brown <broonie@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue
	<alexandre.torgue@...s.st.com>
CC: <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/2] spi: stm32-ospi: Make usage of
 reset_control_acquire/release() API



On 5/5/25 15:12, Philipp Zabel wrote:
> Hi Patrice,
> 
> On Fr, 2025-04-11 at 14:41 +0200, Patrice Chotard wrote:
>> As ospi reset is consumed by both OMM and OSPI drivers, use the reset
>> acquire/release mechanism which ensure exclusive reset usage.
>>
>> This avoid to call reset_control_get/put() in OMM driver each time
>> we need to reset OSPI children and guarantee the reset line stays
>> deasserted.
>>
>> Signed-off-by: Patrice Chotard <patrice.chotard@...s.st.com>
>> ---
>>  drivers/spi/spi-stm32-ospi.c | 15 +++++++++------
>>  1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/spi/spi-stm32-ospi.c b/drivers/spi/spi-stm32-ospi.c
>> index d002b9c16714684e4e4623f9255a7f2660c46fd1..ef840f377459891b559be6d6c0435408fb58a1e9 100644
>> --- a/drivers/spi/spi-stm32-ospi.c
>> +++ b/drivers/spi/spi-stm32-ospi.c
>> @@ -804,7 +804,7 @@ static int stm32_ospi_get_resources(struct platform_device *pdev)
>>  		return ret;
>>  	}
>>  
>> -	ospi->rstc = devm_reset_control_array_get_exclusive(dev);
>> +	ospi->rstc = devm_reset_control_array_get_exclusive_released(dev);
>>  	if (IS_ERR(ospi->rstc))
>>  		return dev_err_probe(dev, PTR_ERR(ospi->rstc),
>>  				     "Can't get reset\n");
>> @@ -936,11 +936,14 @@ static int stm32_ospi_probe(struct platform_device *pdev)
>>  	if (ret < 0)
>>  		goto err_pm_enable;
>>  
>> -	if (ospi->rstc) {
>> -		reset_control_assert(ospi->rstc);
>> -		udelay(2);
>> -		reset_control_deassert(ospi->rstc);
>> -	}
>> +	ret = reset_control_acquire(ospi->rstc);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "Can not acquire reset %d\n", ret);
>> +
>> +	reset_control_assert(ospi->rstc);
>> +	udelay(2);
>> +	reset_control_deassert(ospi->rstc);
>> +	reset_control_release(ospi->rstc);
> 
> Could you keep the reset control (mostly) acquired from probe() to
> remove()? The reset control would have to be released/acquired in OSPI
> suspend/resume so that OMM can temporarily acquire control during OMM
> resume.

Ok

Thanks
Patrice

> 
> regards
> Philipp