linux-kernel - Re: [PATCH v3] spi: stm32-ospi: Make usage of reset_control

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Message-ID: <3c655dad-270d-44e1-b20f-3b15f6cc06f1@foss.st.com>
Date: Mon, 12 May 2025 08:58:28 +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 v3] spi: stm32-ospi: Make usage of
 reset_control_acquire/release() API



On 5/8/25 11:16, Philipp Zabel wrote:
> Hi Patrice,
> 
> On Mi, 2025-05-07 at 18:04 +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>
>> ---
>> Changes in v3:
>>   - Remove previous patch 1/2 as already merged.
>>   - Keep the reset control acquired from probe() to remove().
>>   - Link to v2: https://lore.kernel.org/r/20250411-b4-upstream_ospi_reset_update-v2-0-4de7f5dd2a91@foss.st.com
>>
>> Changes in v2:
>>   - Rebased on spi/for-next (7a978d8fcf57).
>>   - Remove useless check on reset.
>>   - Add error handling on reset_control_acquire().
>>   - Link to v1: https://lore.kernel.org/all/20250410-b4-upstream_ospi_reset_update-v1-0-74126a8ceb9c@foss.st.com/
>> ---
>>  drivers/spi/spi-stm32-ospi.c | 24 ++++++++++++++++++------
>>  1 file changed, 18 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/spi/spi-stm32-ospi.c b/drivers/spi/spi-stm32-ospi.c
>> index 668022098b1eac3628f0677e6d786e5a267346be..b2597b52beb1133155e0d6f601b0632ad4b8e8f5 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_optional_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 +936,13 @@ 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);
>>  
>>  	ret = spi_register_controller(ctrl);
>>  	if (ret) {
>> @@ -983,6 +985,8 @@ static void stm32_ospi_remove(struct platform_device *pdev)
>>  	if (ospi->dma_chrx)
>>  		dma_release_channel(ospi->dma_chrx);
>>  
>> +	reset_control_release(ospi->rstc);
>> +
>>  	pm_runtime_put_sync_suspend(ospi->dev);
>>  	pm_runtime_force_suspend(ospi->dev);
>>  }
>> @@ -993,6 +997,8 @@ static int __maybe_unused stm32_ospi_suspend(struct device *dev)
>>  
>>  	pinctrl_pm_select_sleep_state(dev);
>>  
>> +	reset_control_release(ospi->rstc);
> 
> It would be nice to point out in a comment that OMM will temporarily
> take over control during resume. But either way,
> 
Hi Philipp

Right, i will send a new version by adding this information.

Thanks
Patrice

> Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>



> 
> regards
> Philipp